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查询: 一:查询所有数据 select * from Info 查所有数据 select Code,Name from Info 查特定列
二:根据条件查 select * from Info where Code=’p001′ 一个条件查询 select * from Info where Code=’p001′ and Nation=’n001′ 多条件 并关系 查询 select * from Info where Name=’胡军’ or Nation=’n001′ 多条件 或关系 查询 select * from Car where Price>=50 and Price<=60 范围查询 select * from Car where Price between 50 and 60 范围查询
三:模糊查询 select * from Car where Name like ‘%型’ %通配符代表任意多个字符 select * from Car where Name like ‘%奥迪%’ _通配符代表任意一个字符 select * from Car where Name like ‘_马%’
四:排序 select * from Car order by Price asc 按照价格升序排列 select * from Car order by Price desc 按照价格降序排列 select * from Car order by Price,Oil 按照两列进行排序,前面的为主要的
五:统计函数(聚合函数) select count(Code) from Car 查询表中有多少条数据 select max(Price) from Car 取价格的最大值 select min(Price) from Car 取价格的最小值 select sum(Price) from Car 取价格的总和 select avg(Price) from Car 取价格的平均值
六:分组查询 select Brand from Car group by Brand having count(*)>2 查询所有系列中数量大于2的
七:分页查询 select * from Car limit 0,5 跳过几条数据取几条数据
八:去重查询 select distinct Brand from Car
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