mysql 主键自动增长
Jun 07, 2016 pm 03:47 PM1、把主键定义为自动增长标识符类型 在mysql中,如果把表的主键设为auto_increment类型,数据库就会自动为主键赋。例如: create table customers(id int auto_increment primary key not null, name varchar(15)); insert into customers(name) values(name
1、把主键定义为自动增长标识符类型
在mysql中,如果把表的主键设为auto_increment类型,数据库就会自动为主键赋值。例如:
create table customers(id int auto_increment primary key not null, name varchar(15));
insert into customers(name) values("name1"),("name2");
一旦把id设为auto_increment类型,mysql数据库会自动按递增的方式为主键赋值。在MS SQLServer中,如果把表的主键设为identity类型,数据库就会自动为主键赋值。例如:
create table customers(id int identity(1,1) primary key not null, name varchar(15));
insert into customers(name) values("name1"),("name2");
select id from customers;
查询结果和mysql的一样。由此可见,一旦把id设为identity类型,MSSQLServer数据库会自动按递增的方式为主键赋
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