MYSQL中having和where的区别

having可以显示sql语句查询的条件，与where使用类似，在某些场合可以互换使用

where：设置sql语句的查询条件，条件字段必须是 数据表存在的字段

having：设置sql语句的查询条件，条件字段必须是 查询结果集的字段。

① having和where可以互换使用

select * from sw_goods where goods_price> 5000

select * from sw_goods having goods_price> 5000

② 只能使用where(不能用having)

select goods_id,goods_name from sw_goods where goods_price>10000

select goods_id,goods_name from sw_goods having goods_price>10000 错误

③ 只能使用having (不能用where)

--获得总数量大于5个结果的品牌信息

--select goods_brand_id,count(*) fromsw_goods group by goods_brand_id

select goods_brand_id,count(*) as cnt fromsw_goods group by goods_brand_id having cnt>5

select goods_brand_id,count(*) as cnt fromsw_goods where cnt>5 group by goods_brand_id 错误






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