MySQL adds, modifies, and deletes the column bitsCN.com.
View constraints in MySQL, add constraints, delete constraints, add columns, modify columns, and delete columns
- View the table field information: desc table name;
- View all table information: show create table name;
- Add primary key constraint: alter table name add constraint primary key (for example, PK _ table name) primary key table name (primary key field );
- Add foreign key constraint: alter table from table add constraint foreign key (for example: FK _ slave table _ master table) foreign key from table (foreign key field) references primary table (primary key field );
- Delete primary key constraint: alter table name drop primary key;
- Delete foreign key constraints: alter table name drop foreign key (case sensitive );
- Alter table t_book rename to bbb;
- Add column: alter table name add column name varchar (30 );
- Delete column: alter table name drop column name;
- Modify the column name MySQL:
Alter table name change the name of the column to be changed (eg: xxx) to be converted to (eg: yyy) float; // float is the column type, which can be char, int, date and other types
- Modify the column name SQLServer: exec sp_rename 't_ student. name', 'nn ', 'column ';
- Modify the column name Oracle: alter table name rename column column1 to column2;
- Modify column attributes: alter table name modify column1 varchar (32 );
Sp_rename: the built-in stored procedure of SQL Server, which is used to modify the table definition.
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