ALTER table: Add, modify, delete table columns, constraints, and other table definitions.
- View column information: DESC table name;
- Modify table name: ALTER TABLE T_book Rename to BBB;
- Add column: ALTER TABLE name add column field name varchar (length);
- Delete column: ALTER TABLE name drop column field name;
- Modify Column name mysql:alter table name change cloumn The original field name the new field name data type, while modifying more than one available will be separated, such as change column ..., changing column ...
- Modify the column name Sqlserver:exec sp_rename ' table name. Field name ', ' nn ', ' column ';
- Modify the Column name Oracle:lter table BBB Rename column nnnnn to HH int;
- Modify Column properties: ALTER TABLE name modify field name new data type;
Sp_rename:sqlserver built-in stored procedures for modifying the definition of a table.
MySQL view constraints, add constraints, delete constraints
- View field information for table: DESC table name;
- View all information about the table: Show create table table name;
- Add PRIMARY KEY constraint: ALTER TABLE name add constraint primary key (Shape: Pk_ table name) primary key table name (primary key field);
- Add FOREIGN KEY constraint: ALTER TABLE from TABLE ADD constraint foreign key (shape: Fk_ from Table _ Main Table) foreign key from table (foreign key field) references Main Table (primary key field);
- Delete PRIMARY KEY constraint: ALTER TABLE name drop PRIMARY key;
- Delete FOREIGN KEY constraint: ALTER TABLE name drop FOREIGN key foreign key (case sensitive);
MySQL add columns, modify columns, delete columns
