group分组查询
max? 求最大函數(shù)
select max(goods_price) from goods?
min?? 求最小函數(shù)
select min(goods_price) from goods?
sum? 求總和
select (goods_price) from goods?
avg?? 求平均數(shù)
select avg(goods_price) from goods?
count求總行數(shù)? (求有多少商品)
select count(*) from goods數(shù)了多少次*? 數(shù)絕對的行數(shù) 即便是null? 也計算在內(nèi),而count(列名)查詢的該列不為null的所有行數(shù)
轉(zhuǎn)載于:https://www.cnblogs.com/forphp/p/3432617.html
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