Mysql modifies columns, adds columns, deletes common column commands, and mysql commands

Mysql modifies columns, adds columns, deletes common column commands, and mysql commands

Alter table: add, modify, and delete TABLE columns, constraints, and other TABLE definitions.

View column: desc table name;

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;

Alter 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: lter table bbb rename column nnnnn to hh int;

Modify column attributes: alter table t_book modify name varchar (22); sp_rename: the built-in Stored Procedure of SQLServer, used to modify table definitions.

MySQL view constraints, add constraints, delete constraints add columns, Modify columns, delete columns View 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;

Alter column name MySQL: alter table bbb change nnnnn hh int;

Modify the column name SQLServer: exec sp_rename 't_ student. name', 'nn ', 'column ';

Alter column name Oracle: alter table bbb rename column nnnnn to hh int;

Modify column attributes: alter table t_book modify name varchar (22); sp_rename: the built-in Stored Procedure of SQLServer, used to modify table definitions.