sql group by语法与实例

sql group by语法与实例
group by 语句
group by 语句用于结合合计函数，根据一个或多个列对结果集进行分组。

sql group by 语法

select column_name, aggregate_function(column_name)
from table_name
where column_name operator value
group by column_name

来看一个group by实例

比如表里内容是这样

gameid best top spam

111 1 1 1

121 1 1 0

123 0 1 1

111 1 0 1

我现在要取出best top spam 的数量 结果应该是

gameid best top spam

111 2 1 2
121 1 1 0
123 0 1 1

select gameid, sum(best) as bestcnt, sum(top) as tocnt, sum(spam) as spamcnt
from table
group by gameid

在php教程 中使用方法

$sql = "select gameid,sum(best) as best,sum(top) as top,sum(spam) as spam, from tablename group by gameid order by gameid asc";

再来看个简单一点的实例

数据库教程表table
日期 胜负
2009-12-9 胜
2009-12-9 胜
2009-12-9 负
2009-12-9 负
2009-12-10 负
2009-12-10 胜
2009-12-10 负

查询结果
日期 胜 负
2009-12-9 2 2
2009-12-10 1 2

select 日期,
sum(decode(胜负,'胜',1,0)),
sum(decode(胜负,'负',1,0))
from 数据库表
group by 日期