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This article mainly introduces the specific steps of the basic operation of the SQL library in MySQL, the contents of the article are carefully selected and edited by the author, with a certain pertinence, and is of great significance to everyone's reference, the following is to understand the specific steps of the basic operation of the SQL library in MySQL with the author.

Basic operation of SQL

Basic operation: CURD, that is, add, delete, change and check.

Depending on the object of operation, we can divide the basic operations of SQL into three categories: library operations, table (field) operations, and data operations.

Library operation

1 add new database

Basic syntax: create database + database name + [library options]

Among them, the library option is used to constrain the database, which is optional (with default values). There are two types, namely:

Character set setting: charset/ character set+ specific character set, which is used to represent the encoding format of data storage. Commonly used character sets include GBK and UTF8.

Proofreading set setting: collate+ specific proofreading set, which represents the rules of data comparison, which depends on the character set.

Example: create database TBL_ERROR_CODE charset utf8

Among them, the database name cannot use keywords (characters that are already occupied, such as update and insert, etc.) or reserved words (which may be used in the future, such as access and cast, etc.).

If you must use the keyword or reserved word of the database as the database name, you must enclose it in backquotes, for example:

Create databaseaccesscharset utf8

If you also want to use Chinese as the name of the database, make sure that the database can recognize Chinese (it is strongly recommended not to name the database in Chinese), for example:

-- method to set the Chinese name, where gbk is the default character set of the current database, set names gbk;create database Beijing charset gbk

2 query the database

View all-> basic syntax: show databases

View section (fuzzy query)-> basic syntax: show databases like 'pattern'

Among them, pattern is a matching pattern, and there are two, which are:

%: indicates that multiple characters are matched

_: means to match a single character.

In addition, when matching a database name with an underscore _, you need to add a backslash before the underscore to escape.

Example: show databases like 'TBL%'; means to match all databases that begin with TBL.

View the database creation statement-> basic syntax: show create database + database name

Here, the result may be different from the SQL statement we wrote, because the database optimizes the SQL before executing the SQL statement, and the system saves the optimized result.

3 update the database

Here, it is important to note that the name of the database cannot be changed.

Modifications to the database are limited to the library option, that is, the character set and the proofreading set (the proofreading set depends on the character set).

Basic syntax: alter database + database name + [library options]

Charset/character set [=] character set

Collate [=] proofreading set

Example: alter database TBL_ERROR_CODE charset gbk; means to modify the character set of this database to gbk.

4 Delete the database

Basic syntax: drop database + database name

Here, it is important to note that before deleting the database, you should first perform a backup operation, because the deletion is irreversible, so do not delete the database at will.

Warm reminder: the content enclosed in the symbol [] indicates optional; the symbol + indicates the meaning of connection.

After reading the above specific steps about the basic operation of SQL library in MySQL, many readers must have some understanding. If you need to get more industry knowledge and information, you can continue to follow our industry information column.

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