1. A method of database migration, comprising the steps of:

converting data in a database to be migrated into a table structure and data in a preset format, and exporting the table structure and the data;

converting the exported table structure and data into import files of target databases of different types from the database to be migrated;

and importing the import file into the target database after executing the table building and index building sentences in the target database.

2. The method according to claim 1, wherein the database to be migrated is a MySQL database, and the target database is a MongoDB database.

3. The method of claim 2, wherein converting the data in the database to be migrated into the table structure and the data in the preset format, and exporting the table structure and the data comprises:

generating a table structure and data of the MySQL database to be exported through dump commands in the MySQL database;

and exporting the table structure and the data through a database connection tool.

4. The method of claim 2, wherein converting the exported table structure and data into an import file for a target database of a different type than the database to be migrated comprises:

converting the table building statement and the index statement of the table structure in the MySQL database into a creating set and a creating index statement of the MongoDB database;

and converting the insert statement of the MySQL database into a CSV file or the insert statement of the MongoDB database.

5. The method of claim 4, wherein converting the tabular statement and indexed statement of the table structure in the MySQL database to the create set and create indexed statement of the MongoDB database comprises:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name in each SQL statement in a character string acquisition mode, and generating a table building statement of the MongoDB database based on the acquired table name;

and acquiring an index name and an index field in each SQL statement by matching the primary key, unique key and key character string, and generating the index statement of the MongoDB database based on the acquired index name and index field.

6. The method of claim 5, wherein converting the insert statement of the MySQL database into a CSV file or an insert statement of the MongoDB database comprises:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name between a keyword insert into and a keyword value in each SQL statement and data content after the keyword value;

acquiring all field names and field types according to the acquired table names;

and splicing the table name, the field name and the field type into insert sentences of the MongoDB database, and generating a CSV file according to the obtained field name and the data content.

7. The method of claim 6, wherein importing the import file into the target database after performing the table and index statements in the target database comprises:

importing the generated CSV file into the target database through a mongoimmonport command;

and executing the assembled insert statement in a client side of the MongoDB database to import an import file into the target database.

8. An apparatus for database migration, the apparatus comprising:

the export module is configured to convert data in the database to be migrated into a table structure and data in a preset format and export the table structure and the data;

a conversion module configured to convert the exported table structure and data into an import file of a target database of a different type from the database to be migrated;

the import module is configured to import the import file into the target database after executing the table building and index building statements in the target database.

9. A computer device, comprising:

at least one processor; and

a memory storing computer instructions executable on the processor, the instructions when executed by the processor implementing the steps of the method of any one of claims 1 to 7.

10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.

Background

In the big data era, with the explosive increase of data volume and the continuous change and upgrade of the existing business logic, the traditional relational database such as the MySQL database cannot support the use of the existing system in many scenes, and many systems are upgraded and transformed to use a novel non-relational database, such as the MongoDB database. Along with the upgrading of the system and the change of the database architecture, the business data accumulated in history must be safely migrated to the upgraded and changed database.

At present, each mainstream database only supports migration strategies such as backup export import and the like of the same database, and cannot support migration between two different types of databases.

Disclosure of Invention

In view of this, an object of the embodiments of the present invention is to provide a method, an apparatus, a device and a readable medium for database migration, which enable an M to perform the database migration according to the technical solution of the present invention_yThe SQL database is more convenient to migrate to the MongoDB database, the labor cost is saved, and a guarantee is provided for the change of the system database architecture.

In view of the above object, an aspect of the embodiments of the present invention provides a method for database migration, including the steps of:

converting data in a database to be migrated into a table structure and data in a preset format, and exporting the table structure and the data;

converting the exported table structure and data into import files of target databases of different types from the database to be migrated;

and importing the import file into the target database after executing the table building and index building statements in the target database.

According to one embodiment of the invention, the database to be migrated is a MySQL database, and the target database is a MongoDB database.

According to one embodiment of the invention, converting the data in the database to be migrated into the table structure and the data in the preset format, and exporting the table structure and the data comprises:

generating a table structure and data of the MySQL database to be exported through dump commands in the MySQL database;

the table structure and data are exported through a database connection tool.

According to one embodiment of the present invention, converting the exported table structure and data into an import file of a target database of a different type from the database to be migrated comprises:

converting the table building statement and the index statement of the table structure in the MySQL database into a creating set and an index creating statement of the MongoDB database;

and converting the insert statement of the MySQL database into an insert statement of a CSV file or a MongoDB database.

According to one embodiment of the invention, converting the table building statement and the index statement of the table structure in the MySQL database into the creation set and the creation index statement of the MongoDB database comprises the following steps:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name in each SQL statement in a character string acquisition mode, and generating a table building statement of the MongoDB database based on the acquired table name;

and acquiring an index name and an index field in each SQL statement by matching the primary key, unique key and key character string, and generating the index statement of the MongoDB database based on the acquired index name and index field.

According to one embodiment of the invention, converting the insert statement of the MySQL database into the insert statement of the CSV file or the MongoDB database comprises the following steps:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name between a keyword insert into and a keyword value in each SQL statement and data content after the keyword value;

acquiring all field names and field types according to the acquired table names;

and spelling an insert sentence of the MongoDB database according to the acquired table name, field name and field type, and generating a CSV file according to the acquired field name and data content.

According to an embodiment of the present invention, importing an import file into a target database after executing a table building and index building statement in the target database includes:

importing the generated CSV file into a target database through a mongoimprort command;

and executing the assembled insert statement in a client of the MongoDB database to import the import file into the target database.

In another aspect of the embodiments of the present invention, there is also provided an apparatus for database migration, including:

the export module is configured to convert the data in the database to be migrated into a table structure and data in a preset format and export the table structure and the data;

the conversion module is configured to convert the exported table structure and the data into an import file of a target database which is different from the database to be migrated;

and the import module is configured to import the import file into the target database after executing the table building and the index building statement in the target database.

In another aspect of an embodiment of the present invention, there is also provided a computer apparatus including:

at least one processor; and

a memory storing computer instructions executable on the processor, the instructions when executed by the processor implementing the steps of any of the methods described above.

In another aspect of the embodiments of the present invention, there is also provided a computer-readable storage medium storing a computer program, which when executed by a processor implements the steps of any one of the above-mentioned methods.

The invention has the following beneficial technical effects: according to the method for migrating the database, provided by the embodiment of the invention, the data in the database to be migrated is converted into the table structure and the data in the preset format, and the table structure and the data are exported; converting the exported table structure and data into import files of target databases of different types from the database to be migrated; the technical scheme of importing the import file into the target database after table building and index building are executed in the target database can enable the MySQL database to be more conveniently migrated to the MongoDB database, save labor cost and provide guarantee for changing the system database architecture.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained by using the drawings without creative efforts.

FIG. 1 is a schematic flow chart diagram of a method of database migration in accordance with one embodiment of the present invention;

FIG. 2 is a schematic diagram of an apparatus for database migration according to one embodiment of the present invention;

FIG. 3 is a schematic diagram of a computer device according to one embodiment of the present invention;

fig. 4 is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments of the present invention are described in further detail with reference to the accompanying drawings.

In view of the above objects, a first aspect of embodiments of the present invention proposes an embodiment of a method of database migration. Fig. 1 shows a schematic flow diagram of the method.

As shown in fig. 1, the method may include the steps of:

s1, converting the data in the database to be migrated into the table structure and data in the preset format, and exporting the table structure and data.

The technical scheme of the invention is mainly applied to the migration of the MySQL database to the MongoDB database, the table structure, the index and the user data in the original MySQL database can be rapidly and inerrably migrated to the new MongoDB database through the technical scheme of the invention, the system architecture is convenient to upgrade and change, the database to be migrated is the MySQL database, the target database is the MongoDB database, the table structure and the data of the MySQL database to be exported can be generated through the dump command in the MySQL database, and the command can be: myslqldump-h < host > -u < username > -p < password > -database < dbname > >/path/. sql, and then the table structure and data are exported via database connection tools, which may be, for example, Navicat tools and MySQLWorkbench tools, among others.

S2 converting the exported table structure and data into import files of target databases of different types from the database to be migrated.

Firstly, converting a table building statement and an index statement of a table structure in a MySQL database into a building set and a building index statement of a MongoDB database, traversing all derived data, dividing the data into a plurality of SQL statements by taking a semicolon as a breakpoint, then obtaining a table name in each SQL statement in a character string obtaining mode, generating the table building statement of the MongoDB database based on the obtained table name, then obtaining an index name and an index field in each SQL statement by matching keywords primary key, unique key and key character strings, and generating the index statement of the MongoDB database based on the obtained index name and the obtained index field, wherein the index name and the index field need to be corresponding to each SQL statement, namely the table name, the index name and the index field in each SQL statement need to be corresponding. Secondly, converting insert sentences of the MySQL database into insert sentences of a CSV file or a MongoDB database, traversing all the derived data, dividing the data into SQL sentences by taking a semicolon as a breakpoint, acquiring a table name between a keyword insert and keyword values in each SQL sentence and data content behind the keyword values, acquiring all field names and field types according to the acquired table name, assembling the table name, the field names and the field types into insert sentences of the MongoDB database, and generating a CSV file and a CSV command according to the acquired field names and the data content, wherein the table name and the data content, the field names and the field types in each SQL sentence need to correspond to each other.

S3, the import file is imported into the target database after the table establishment and the index establishment are executed in the target database.

The data import of the MongoDB database is divided into two steps, firstly, the table establishment and the index establishment of the MongoDB database are executed, then the CSV file and the CSV command obtained in the previous step are directly executed through a mongoimprort command, the data import is finished after the execution is finished, or the insert statement set output in the previous step is used for executing the insert statement at the MongoDB client side to finish the data import.

By the technical scheme, the migration of the MySQL database to the MongoDB database is more convenient, the labor cost is saved, and the change of the system database architecture is guaranteed.

In a preferred embodiment of the present invention, the database to be migrated is a MySQL database, and the target database is a MongoDB database.

In a preferred embodiment of the present invention, converting the data in the database to be migrated into the table structure and the data in the preset format, and exporting the table structure and the data comprises:

generating a table structure and data of the MySQL database to be exported through dump commands in the MySQL database, wherein the commands can be mysqldump-h < host > -u < username > -p < password > -database < dbname > >/path/. sql;

the table structure and data are exported through a database connection tool, which may be a Navicat tool or a MySQLWorkbench tool, etc.

In a preferred embodiment of the present invention, converting the exported table structure and data into an import file of a target database of a different type from the database to be migrated comprises:

converting the table building statement and the index statement of the table structure in the MySQL database into a creating set and an index creating statement of the MongoDB database;

and converting the insert statement of the MySQL database into an insert statement of a CSV file or a MongoDB database.

In a preferred embodiment of the present invention, converting the table building statement and the index statement of the table structure in the MySQL database into the creation set and the creation index statement of the MongoDB database comprises:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name in each SQL statement in a character string acquisition mode, and generating a table building statement of the MongoDB database based on the acquired table name;

and acquiring an index name and an index field in each SQL statement by matching the primary key, unique key and key character string, and generating the index statement of the MongoDB database based on the acquired index name and index field.

The method comprises the steps of obtaining a table name in a MySQL database table building statement in a character string intercepting mode, generating a MongoDB database table building statement according to the obtained table name, obtaining an index name and an index field by matching keyword primary keys, unique keys and key character strings, and generating the MongoDB database index statement according to the obtained index name and the index field, wherein the keyword primary keys and the unique keys are mapped into unique indexes in the MongoDB database, the keyword keys are mapped into common indexes, and a table field and data type list are obtained by separating commas and spaces, wherein a conversion example is as follows:

MySQL build statement as

The converted MongoDB statement is

db.createCollection('testTable')；

db.testTable.createIndex({"id":1},{"unique":true})；

db.testTable.createIndex({"name":1},{"unique":true,"name":"name_index"})；

db.testTable.createIndex({"age":1},{"name":"age_index"})；

The fields of the converted table are listed as

In a preferred embodiment of the invention, converting the insert statement of the MySQL database into the insert statement of the CSV file or the MongoDB database comprises:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name between a keyword insert into and a keyword value in each SQL statement and data content after the keyword value;

acquiring all field names and field types according to the acquired table names;

and spelling an insert sentence of the MongoDB database according to the acquired table name, field name and field type, and generating a CSV file according to the acquired field name and data content.

An example of the conversion is as follows:

the MySQL insert statement is

INSERT INTO`testTable`VALUES(1,"zhangsan",20),(2,"lisi",19)；

The converted CSV file and import command are

id,name,age

1,zhangsan,20

2,lisi,19

mongoimport-d test-c testTable--type csv--columnsHaveTypes--fields"id.int32(),name.string(),age,int32()"--file./test.csv

The converted MongoDB insert statement is

db.testTable.insert({"id":1,"name":"zhangsan","age":20})；

db.testTable.insert({"id":2,"name":"lisi","age":19})。

In a preferred embodiment of the present invention, importing an import file into a target database after executing a table building and index building statement in the target database includes:

importing the generated CSV file into a target database through a mongoimprort command;

and executing the assembled insert statement in a client of the MongoDB database to import the import file into the target database.

By the technical scheme, the migration of the MySQL database to the MongoDB database is more convenient, the labor cost is saved, and the change of the system database architecture is guaranteed.

It should be noted that, as will be understood by those skilled in the art, all or part of the processes in the methods of the above embodiments may be implemented by instructing relevant hardware through a computer program, and the above programs may be stored in a computer-readable storage medium, and when executed, the programs may include the processes of the embodiments of the methods as described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like. The embodiments of the computer program may achieve the same or similar effects as any of the above-described method embodiments.

Furthermore, the method disclosed according to an embodiment of the present invention may also be implemented as a computer program executed by a CPU, and the computer program may be stored in a computer-readable storage medium. The computer program, when executed by the CPU, performs the above-described functions defined in the method disclosed in the embodiments of the present invention.

In view of the above object, according to a second aspect of the embodiments of the present invention, there is provided an apparatus for database migration, as shown in fig. 2, the apparatus 200 includes:

and the export module is configured to convert the data in the database to be migrated into a table structure and data in a preset format and export the table structure and the data.

The technical scheme of the invention is mainly applied to the migration of the MySQL database to the MongoDB database, the table structure, the index and the user data in the original MySQL database can be rapidly and inerrably migrated to the new MongoDB database through the technical scheme of the invention, the system architecture is convenient to upgrade and change, the database to be migrated is the MySQL database, the target database is the MongoDB database, the table structure and the data of the MySQL database to be exported can be generated through the dump command in the MySQL database, and the command can be: myslqldump-h < host > -u < username > -p < password > -database < dbname > >/path/. sql, and then the table structure and data are exported via database connection tools, which may be, for example, Navicat tools and MySQLWorkbench tools, among others.

And the conversion module is configured to convert the exported table structure and the data into an import file of a target database which is different from the database to be migrated.

The conversion module is also configured to convert the table building statements and the index statements of the table structure in the MySQL database into a set and an index building statement of the MongoDB database, traverse all the derived data, divide the data into a plurality of SQL statements with a semicolon as a break point, acquire a table name in each SQL statement in a character string acquisition mode, generate the table building statements of the MongoDB database based on the acquired table names, acquire an index name and an index field in each SQL statement by matching key keys, unique key and key character strings, and generate the index statements of the MongoDB database based on the acquired index name and index field, wherein the index name and the index field need to be corresponding to each SQL statement, that is, the table name, the index name and the index field in each SQL statement need to be corresponding. The method comprises the steps of converting insert sentences of a MySQL database into insert sentences of a CSV file or a MongoDB database, traversing all derived data, dividing the data into SQL sentences by taking a semicolon as a breakpoint, then obtaining a table name between a keyword insert and a keyword value in each SQL sentence and data content after the keyword value, then obtaining all field names and field types according to the obtained table name, splicing the insert sentences of the MongoDB database according to the obtained table name, field names and field types, and generating CSV files and CSV commands according to the obtained field names and data content, wherein the table name and data content, the field names and the field types in each SQL sentence need to correspond to each other.

And the import module is configured to import the import file into the target database after executing the table building and the index building statement in the target database.

The import module is also configured to execute the table building and index building of the MongoDB database, then directly execute the CSV file and the CSV command obtained in the previous step through the mongoimmonport command, and finish data import after the execution is finished, or execute the insert statement on the MongoDB client by using the insert statement set output in the previous step to finish the data import.

In a preferred embodiment of the present invention, the database to be migrated is a MySQL database, and the target database is a MongoDB database.

In a preferred embodiment of the present invention, the export module is further configured to:

generating a table structure and data of the MySQL database to be exported through dump commands in the MySQL database;

the table structure and data are exported through a database connection tool.

In a preferred embodiment of the present invention, the conversion module is further configured to:

converting the table building statement and the index statement of the table structure in the MySQL database into a creating set and an index creating statement of the MongoDB database;

and converting the insert statement of the MySQL database into an insert statement of a CSV file or a MongoDB database.

In a preferred embodiment of the present invention, the conversion module is further configured to:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name in each SQL statement in a character string acquisition mode, and generating a table building statement of the MongoDB database based on the acquired table name;

and acquiring an index name and an index field in each SQL statement by matching the primary key, unique key and key character string, and generating the index statement of the MongoDB database based on the acquired index name and index field.

In a preferred embodiment of the present invention, the conversion module is further configured to:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name between a keyword insert into and a keyword value in each SQL statement and data content after the keyword value;

acquiring all field names and field types according to the acquired table names;

and spelling an insert sentence of the MongoDB database according to the acquired table name, field name and field type, and generating a CSV file according to the acquired field name and data content.

In a preferred embodiment of the present invention, the import module is further configured to:

importing the generated CSV file into a target database through a mongoimprort command;

and executing the assembled insert statement in a client of the MongoDB database to import the import file into the target database.

In view of the above object, a third aspect of the embodiments of the present invention provides a computer device. Fig. 3 is a schematic diagram of an embodiment of a computer device provided by the present invention. As shown in fig. 3, an embodiment of the present invention includes the following means: at least one processor S21; and a memory S22, the memory S22 storing computer instructions S23 executable on the processor, the instructions when executed by the processor implementing the method of:

converting data in a database to be migrated into a table structure and data in a preset format, and exporting the table structure and the data;

converting the exported table structure and data into import files of target databases of different types from the database to be migrated;

and importing the import file into the target database after executing the table building and index building statements in the target database.

In a preferred embodiment of the present invention, the database to be migrated is a MySQL database, and the target database is a MongoDB database.

In a preferred embodiment of the present invention, converting the data in the database to be migrated into a table structure and data in a preset format, and exporting the table structure and data comprises:

generating a table structure and data of the MySQL database to be exported through dump commands in the MySQL database;

and exporting the table structure and the data through a database connection tool.

In a preferred embodiment of the present invention, converting the exported table structure and data into an import file of a target database different from the database to be migrated includes:

converting the table building statement and the index statement of the table structure in the MySQL database into a creating set and a creating index statement of the MongoDB database;

and converting the insert statement of the MySQL database into a CSV file or the insert statement of the MongoDB database.

In a preferred embodiment of the present invention, converting the table building statement and the index statement of the table structure in the MySQL database into the creation set and the creation index statement of the MongoDB database includes:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name in each SQL statement in a character string acquisition mode, and generating a table building statement of the MongoDB database based on the acquired table name;

and acquiring an index name and an index field in each SQL statement by matching the primary key, unique key and key character string, and generating the index statement of the MongoDB database based on the acquired index name and index field.

In a preferred embodiment of the present invention, converting the insert statement of the MySQL database into a CSV file or an insert statement of the MongoDB database comprises:

traversing all the exported data, and cutting the data into SQL sentences by taking the semicolons as breakpoints;

acquiring a table name between a keyword insert into and a keyword value in each SQL statement and data content after the keyword value;

acquiring all field names and field types according to the acquired table names;

and splicing the table name, the field name and the field type into insert sentences of the MongoDB database, and generating a CSV file according to the obtained field name and the data content.

In a preferred embodiment of the present invention, importing the import file into the target database after executing the table and index building statement in the target database includes:

importing the generated CSV file into the target database through a mongoimmonport command;

and executing the assembled insert statement in a client side of the MongoDB database to import an import file into the target database.

In view of the above object, a fourth aspect of the embodiments of the present invention proposes a computer-readable storage medium. FIG. 4 is a schematic diagram illustrating an embodiment of a computer-readable storage medium provided by the present invention. As shown in fig. 4, the computer readable storage medium stores S31 a computer program that, when executed by a processor, performs the method as described above S32.

Furthermore, the methods disclosed according to embodiments of the present invention may also be implemented as a computer program executed by a processor, which may be stored in a computer-readable storage medium. Which when executed by a processor performs the above-described functions defined in the methods disclosed in embodiments of the invention.

Further, the above method steps and system elements may also be implemented using a controller and a computer readable storage medium for storing a computer program for causing the controller to implement the functions of the above steps or elements.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as software or hardware depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed embodiments of the present invention.

In one or more exemplary designs, the functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk, blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The foregoing is an exemplary embodiment of the present disclosure, but it should be noted that various changes and modifications could be made herein without departing from the scope of the present disclosure as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the disclosed embodiments described herein need not be performed in any particular order. Furthermore, although elements of the disclosed embodiments of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly supports the exception. It should also be understood that "and/or" as used herein is meant to include any and all possible combinations of one or more of the associated listed items.

The numbers of the embodiments disclosed in the embodiments of the present invention are merely for description, and do not represent the merits of the embodiments.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, of embodiments of the invention is limited to these examples; within the idea of an embodiment of the invention, also technical features in the above embodiment or in different embodiments may be combined and there are many other variations of the different aspects of the embodiments of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of the embodiments of the present invention are intended to be included within the scope of the embodiments of the present invention.