1:这一条是条件写在最后的WHERE
SELECT *
FROM Pub_Goods AS a INNER JOIN
Pub_Kind AS b ON a.KindCode = b.Code INNER JOIN
Pub_Type AS c ON b.TypeCode = c.Code
WHERE (a.Name = '产品名字') AND (b.Name = '分类名字') AND (c.Name = '类型名字')
2:这一条是条件写在On
SELECT *
FROM Pub_Goods AS a INNER JOIN
Pub_Kind AS b ON a.KindCode = b.Code AND a.Name = '产品名字' AND b.Name = '分类名字' INNER JOIN
Pub_Type AS c ON b.TypeCode = c.Code AND c.Name = '类型名字'
----------------
上面两条SQL要MS-SQL和Oracle中效率的详细区别
谢谢
SELECT *
FROM Pub_Goods AS a INNER JOIN
Pub_Kind AS b ON a.KindCode = b.Code INNER JOIN
Pub_Type AS c ON b.TypeCode = c.Code
WHERE (a.Name = '产品名字') AND (b.Name = '分类名字') AND (c.Name = '类型名字')
2:这一条是条件写在On
SELECT *
FROM Pub_Goods AS a INNER JOIN
Pub_Kind AS b ON a.KindCode = b.Code AND a.Name = '产品名字' AND b.Name = '分类名字' INNER JOIN
Pub_Type AS c ON b.TypeCode = c.Code AND c.Name = '类型名字'
----------------
上面两条SQL要MS-SQL和Oracle中效率的详细区别
谢谢
第二句 是直接条件关联
感觉第二个执行效率好些。