Sqlite、MySQL和SQL Server中INSERT ... SELECT ... WHERE NOT EXISTS的用法

Sqlite、MySQL和SQL Server中INSERT … SELECT … WHERE NOT EXISTS的用法

下面介绍Mysql和Sqlite和Sqlserver中，根据select的条件判断是否插入。例如：

一、Mysql中：

INSERT INTO books (name) SELECT ‘SongXingzhu’ FROM dual WHERE NOT EXISTS
(SELECT id FROM books WHERE id = 1)

二、Sqlite中：

由于Sqlite中没有临时表：dual

所以，需要这样写

INSERT INTO books (name) SELECT ‘Songxingzhu’ WHERE NOT EXISTS (SELECT id
FROM books WHERE id = 1)

三、Sqlserver中：

SqlServer中需要另一种写法：

IF NOT EXISTS (SELECT id FROM _books _WHERE id = 1) INSERT INTO books
(name) SELECT ‘Songxingzhu’