赞
踩
SELECT column_name, aggregate_function(column_name) FROM table_name GROUP BY column_name
//aggregate_function是函数名,修改此值使用不同的函数
select nation,sum(price) from testtable group by (nation);
SELECT column_name
FROM table_name1
INNER JOIN table_name2
ON table_name1.column_name=table_name2.column_name
- 将表1和表2的数据通过id值联合展示,语句:select ttable1.id,ttable1.name,ttable2.price from ttable1 inner join ttable2 on ttable1.id=ttable2.id;
- 对于匹配不到的列,如表二多了一个id为4的一行数据,进行内联查询时,不进行展示
SELECT column_name
FROM table_name1
LEFT JOIN table_name2
ON table_name1.column_name=table_name2.column_name
SELECT column_name
FROM table_name1
RIGHT JOIN table_name2
ON table_name1.column_name=table_name2.column_name
select * from ttable1 right join ttable2 on ttable1.id=ttable2.id;
SELECT column_name
FROM table_name1
FULL JOIN table_name2
ON table_name1.column_name=table_name2.column_name
select * from ttable1 full join ttable2 on ttable1.id=ttable2.id;
Copyright © 2003-2013 www.wpsshop.cn 版权所有,并保留所有权利。