MySQL View constraints, add constraints, delete constraints, add columns, modify columns, delete columns
- 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);
- Modify table name: ALTER TABLE T_book Rename to BBB;
- Add column: ALTER TABLE name add column name varchar (30);
- Delete column: ALTER TABLE table name drop column name;
- Modify Column name Mysql:alter table BBB change nnnnn hh int;
- Modify the column name Sqlserver:exec sp_rename ' t_student.name ', ' nn ', ' column ';
- Modify the Column name Oracle:alter table BBB Rename column nnnnn to HH int;
- Modify Column properties: ALTER TABLE T_book modify name varchar (22);
MySQL add columns, modify columns, delete columns
