--check约束
create table [user]( userName nvarchar(50) check(len(username) between 5 and 15), pwd nvarchar(10) check(len(pwd between 6 and 8)))
create table [user]( userName nvarchar(50) check(len(username) between 5 and 15), pwd nvarchar(10) check(len(pwd between 6 and 8)))
create table [user]( userName nvarchar(50) check(len(username) between 5 and 15), pwd nvarchar(10) check(len(pwd between 6 and 8)))其实这种情况基本上都是在客户端前台来限制的比后台判断更好一些
(
userName nvarchar(50) check(len(userName) between 5 and 15),
pwd nvarchar(10) check(len(pwd) between 6 and 8)
)-- orcreate table [user]
(
userName nvarchar(50),
pwd nvarchar(10) check(len(pwd) between 6 and 8),
constraint ch_user check((len(userName) between 5 and 15) and (len(pwd) between 6 and 8))
)
create table [user]( userName nvarchar(50) check(len(username) between 5 and 15), pwd nvarchar(10) check(len(pwd) between 6 and 8))
create table [user]( userName nvarchar(50) check(len(username) between 5 and 15), pwd nvarchar(10) check(len(pwd) between 6 and 8))
--测试数据
insert [user] values('shuiniu','abc') --失败,密码长度不够
insert [user] values('shui','abcdefg') --失败,用户名长度长度不够
insert [user] values('shuiniu','shuiniu') --成功select * from [user]/*
userName pwd
-------------------------------------------------- ----------
shuiniu shuiniu(所影响的行数为 1 行)
*/