mysql查询高级用法

Posted 2020-08-16 Xiao|Deng

联合查询
select   a.* , b.adress ,  b.name   from   a , b   where   a.sbNo = b.cdid  order by   a.sbNo , a.STime
select a.a_id, a.a_name, b.b_name from A a, B a where a.b_id = b.b_id //联合查询 

insert into table1 (xx,yy,zz)  select xx,yy,zz from table2;


select axx as id, att as name from tb1
union
select bxx as id, btt as name from tb2


整合有关联的两个数据表里的字段
update  TableA AS ta,   TableB AS tb    SET    ta.field1 = tb.field1    WHERE    ta.id = tb.ta_id


//经典案例
（新用户）通过表A获取的记录集，如下：
1   2012-11-1
3   2012-11-2
8   2012-11-5

（老用户）通过表B获取的记录集，如下：
5   2012-11-1
3   2012-11-2
我想将这两个结果集合并为一个结果集。显示的结果如下：

日期         新用户    老用户
2012-11-1     1          5
2012-11-2     3          3
2012-11-5     8          0
select   a.col2, a.id, ifnull(b.id, 0)   from     newuser   a    left  join     olduser   b   on   a.col2=b.col2;

http://www.cnblogs.com/JuneZhang/archive/2010/08/26/1809306.html