insert into 密码表(用户名,密码) select distinct "admin","12345" from PASSWORDTBL where 用户名<>'admin'可将admin、12345修改为变量
if not exists(select 1 from tb where UserID='X275' insert into tb(UserID,Password) select 'X275','123456' 程序代码: private bool CheckUser(string UserID, string Paswd) { SqlConnection cnn = new SqlConnection(....); SqlCommand cmd=new SqlCommand(); //先验证是否存在此用户,若不存在则插入,并返回TRUE,若存在则验证密码不对则返回false;
}
if not exists(select 1 from 密码表where 表ID ='admin') begin insert into 密码表 values('admin','12345') end if exists(select 1 from 密码表where 表ID ='admin') begin return end
insert into PASSWORDTBL(用户名,密码) select 'admin','12345' from 密码表 t where not exists(select 1 from PASSWORDTBL where 用户名='admin' and 用户名=t.用户名 )
if not exists(select * from 用户表)
--创建测试表 create table PASSWORDTBL(用户名 nvarchar(20),密码 varchar(20)) insert into PASSWORDTBL select 'aaa','bbb' go --实现楼主的需求: insert into PASSWORDTBL(用户名,密码) select 'admin','12345' from PASSWORDTBL where not exists(select 1 from PASSWORDTBL where 用户名='admin') go --检验 select * from PASSWORDTBL /* 用户名 密码 -------------------- -------------------- aaa bbb admin 12345(2 行受影响)*/ drop table PASSWORDTBL
--创建测试表 create table PASSWORDTBL(用户名 nvarchar(20),密码 varchar(20)) insert into PASSWORDTBL select 'aaa','bbb' go --实现楼主的需求: insert into PASSWORDTBL(用户名,密码) select 'admin','12345' from PASSWORDTBL where not exists(select 1 from PASSWORDTBL where 用户名='admin') go --再次插入 insert into PASSWORDTBL(用户名,密码) select 'admin','678910' from PASSWORDTBL where not exists(select 1 from PASSWORDTBL where 用户名='admin') go --检验 select * from PASSWORDTBL /* 用户名 密码 -------------------- -------------------- aaa bbb admin 12345(2 行受影响)*/ drop table PASSWORDTBL
where 用户名<>'admin'可将admin、12345修改为变量
if not exists(select 1 from tb where UserID='X275'
insert into tb(UserID,Password) select 'X275','123456' 程序代码:
private bool CheckUser(string UserID, string Paswd)
{
SqlConnection cnn = new SqlConnection(....);
SqlCommand cmd=new SqlCommand(); //先验证是否存在此用户,若不存在则插入,并返回TRUE,若存在则验证密码不对则返回false;
}
begin
insert into 密码表 values('admin','12345')
end
if exists(select 1 from 密码表where 表ID ='admin')
begin
return
end
PASSWORDTBL(用户名,密码)
select
'admin','12345'
from
密码表 t
where
not exists(select 1 from PASSWORDTBL where 用户名='admin' and 用户名=t.用户名 )
create table PASSWORDTBL(用户名 nvarchar(20),密码 varchar(20))
insert into PASSWORDTBL select 'aaa','bbb'
go
--实现楼主的需求:
insert into PASSWORDTBL(用户名,密码)
select 'admin','12345'
from PASSWORDTBL
where not exists(select 1 from PASSWORDTBL where 用户名='admin')
go
--检验
select * from PASSWORDTBL
/*
用户名 密码
-------------------- --------------------
aaa bbb
admin 12345(2 行受影响)*/
drop table PASSWORDTBL
create table PASSWORDTBL(用户名 nvarchar(20),密码 varchar(20))
insert into PASSWORDTBL select 'aaa','bbb'
go
--实现楼主的需求:
insert into PASSWORDTBL(用户名,密码)
select 'admin','12345'
from PASSWORDTBL
where not exists(select 1 from PASSWORDTBL where 用户名='admin')
go
--再次插入
insert into PASSWORDTBL(用户名,密码)
select 'admin','678910'
from PASSWORDTBL
where not exists(select 1 from PASSWORDTBL where 用户名='admin')
go
--检验
select * from PASSWORDTBL
/*
用户名 密码
-------------------- --------------------
aaa bbb
admin 12345(2 行受影响)*/
drop table PASSWORDTBL