摘要:
if exists(select * from sysdatabases where name='testdb') drop database testdb go create database testdb go create table login ( uid int primary key identity(1,1), uname varchar(20), upwd varchar(50) ) go insert login values('admin','admin') insert login values('test' 阅读全文
摘要:
select * from t1; ID NAME---------- -------------------- 1 aaa 2 bbbselect * from t2; ID AGE---------- ---------- 1 20 3 30左外连接:select * from t1 left join t2 on t1.id=t2.id; ID NAME ID AGE---------- -------------------- ---------- ---------- 1 aaa 1 20 2 bbb右外连接:select * from t1 right join t2 on t1. 阅读全文