MySQL joins columns, changes columns, and deletes columns.

Source: Internet
Author: User
Tags joins mysql view



MySQL joins columns, changes columns, deletes columns

ALTER table: Add, change, delete table columns, constraints and other table definitions.

    • View column: Desc table name;
    • Change 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;
    • Change Column name mysql:alter table BBB change nnnnn hh int;
    • Change the column name sqlserver:exec sp_rename ' t_student.name ', ' nn ', ' column ';
    • Change Column name oracle:lter table BBB Rename column nnnnn to HH int;
    • Change column properties: ALTER TABLE T_book modify name varchar (22);

Sp_rename:sqlserver built-in stored procedures, with the definition of the change table.



MySQL view constraint, add constraint, delete constraint join column, alter COLUMN, delete column

    • 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 (distinguish uppercase and lowercase);
    • change table name: ALTER TABLE T_book Rename to BBB;
    • add column: ALTER TABLE name add column name varchar (+);
    • delete column: ALTER TABLE table name drop column name;
    • change column name Mysql:alter table bbb changes nnnnn hh int;
    • change column name sqlserver:exec sp_rename ' T_student.name ', ' NN ', ' column ';
    • change column name oracle:alter table BBB Rename column nnnnn to HH int;
    • Change column properties: ALTER TABLE T_book modify name varchar;

Sp_rename:sqlserver built-in stored procedures, with the definition of the change table.


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