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In mysql, the statement to modify table comments is "alter table table name comment 'comment content';"; the alter statement is used to modify the structure of a table. It can add or delete columns, or change the table. The type of comment and table. The comment attribute is used to represent comments.
The operating environment of this tutorial: windows10 system, mysql8.0.22 version, Dell G3 computer.
“alter table 表名 comment '注释内容';”
alterTABLE allows you to modify the structure of an existing table. For example, you can add or delete columns, create or delete indexes, change the type of existing columns, or rename columns or the table itself. You can also change the table annotation and the table type.
Common usage of alter
1: Delete a column
ALTER TABLE 【表名字】 DROP 【列名称】
2: Add a column
ALTER TABLE 【表名字】 ADD 【列名称】 INT NOT NULL COMMENT '注释说明'
3: Modify the type information of a column
ALTER TABLE 【表名字】 CHANGE 【列名称】【新列名称(这里可以用和原来列同名即可)】 BIGINT NOT NULL COMMENT '注释说明'
4: Rename column
ALTER TABLE 【表名字】 CHANGE 【列名称】【新列名称】 BIGINT NOT NULL COMMENT '注释说明'
5: Rename table
ALTER TABLE 【表名字】 RENAME 【表新名字】
6: Delete primary key in table
Alter TABLE 【表名字】 drop primary key
7: Add primary key
ALTER TABLE sj_resource_charges ADD CONSTRAINT PK_SJ_RESOURCE_CHARGES PRIMARY KEY (resid,resfromid)
Recommended learning: mysql video tutorial
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