What are the add constraint statements in mysql
This article introduces what add constraint statements in mysql, the content is very detailed, interested friends can refer to, I hope it can be helpful to you.
-- add table comments
CREATE TABLE user (
Id int PRIMARY KEY AUTO_INCREMENT COMMENT 'primary key'
Name VARCHAR (10) COMMENT 'name'
Age TINYINT
Birth DATETIME
Salary DOUBLE (7 dint 2)
Tel char (11)
) COMMENT 'user Table'
-- add default constraint
CREATE TABLE user (
Id int PRIMARY KEY AUTO_INCREMENT COMMENT 'primary key'
Name VARCHAR (10) COMMENT 'name'
Age TINYINT
Birth DATETIME
Salary DOUBLE (7 dint 2)
Tel char (11)
) COMMENT 'user Table'
-- add unique constraints
CREATE TABLE register (
Id int PRIMARY KEY AUTO_INCREMENT
Name VARCHAR (10) UNIQUE KEY
RegisTime TIMESTAMP DEFAULT CURRENT_TIMESTAMP ()
Fund DOUBLE (9 dint 2) DEFAULT 1000000.00
Tel char (11)
)
-- non-empty constraint
CREATE TABLE register (
Id int PRIMARY KEY AUTO_INCREMENT
Name VARCHAR (10) DEFAULT NULL UNIQUE KEY
RegisTime TIMESTAMP DEFAULT CURRENT_TIMESTAMP ()
Fund DOUBLE (9 dint 2) DEFAULT 1000000.00
Tel char (11) NOT NULL
)
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