select * from txt1 

select * from txt2 

select * from txt1 where name in (select name from txt2 where chk = 0) 

select * from txt1 where name not in (select name from txt2 where chk = 0) 

select * from txt1 inner join txt2 on txt1.name = txt2.name 

select * from txt1 left join txt2 on txt1.name = txt2.name 

select * from txt1 right join txt2 on txt1.name = txt2.name 

select * from txt1,txt2 where txt1.name = txt2.name Order By txt2.ID Desc 

select Txt1.name,Sum(Txt1.Sumint) from txt1,txt2 where txt1.name =txt2.name Group by txt1.name 

select count(Txt1.name),sum(sumint) from txt1,txt2 where txt1.name =txt2.name having sum(sumint)<10 

select count(Txt1.name),sum(sumint) from txt1,txt2 where txt1.name =txt2.name having Sum(sumint) >50 

select * from txt1,txt2 where txt1.name <>txt2.name Order by Txt1.Name compute Sum(sumint) by txt1.name 

insert into txt3 select name,Sumint from txt1 

In:等值连接，用来查找多表相同字段的记录 

Not In:非等值连接，用来查找不存在的记录 

Inner join:内连接，主要用来查找都符合条件的记录 

Left join:左连接，主要用来查找左边有，右边没有的用空值表达 

Right join:右连接，主要用来查找右边有，左边没有的用空值表达 

Order By:升序 Asc 降序 Desc 

Group By:分组排序 按字段分组(如按班级分),使用的都要有集合函数存在 

Having :对分组条件进行判断,使用都要确保每个字段都要用集合函数 

COMPUTE BY：子句使您得以用同一 SELECT 语句既查看明细行，又查看汇总行。可以计算子组的汇总值，也可以计算整个结果集的汇总值。 

行聚合函数名称；例如，SUM、AVG、MIN、MAX 或 COUNT 

insert into:主要把查询的语句插入到新表。 

txt1表的数据 

ID Name SumInt 

1 张三 55 

2 李四 85 

3 王五 85 

4 赵六 855 

txt2表的数据 

ID Name Chk 

1 张三 0 

2 李四1 1 

3 王五 0 

4 赵六 0