强烈推荐:将选项 ANSI_NULLS 设置为On,在与Null值比较时使用 is null 或 is not null 查看和设置该选项的值 SET ANSI_NULLS ON --SET ANSI_NULLS OFF DECLARE @ANSI_NULLS VARCHAR(3) = 'OFF'; IF ( (32 & @@OPTIONS) = 32 ) SET @ANSI_NULLS = 'ON'; SELECT @ANSI_NULLS AS [ANSI_NULLS Option]; Whe
https://docs.microsoft.com/en-us/sql/relational-databases/tables/specify-computed-columns-in-a-table?view=sql-server-2017 Before You Begin Limitations and Restrictions A computed column cannot be used as a DEFAULT or FOREIGN KEY constraint definition
w https://dev.mysql.com/doc/refman/5.7/en/create-index.html MySQL :: MySQL 5.7 Reference Manual :: B.5.4.3 Problems with NULL Valueshttps://dev.mysql.com/doc/refman/5.7/en/problems-with-null.html You can add an index on a column that can have NULL va
已经很久没用使用这个脚本了,今天用到,并做修改,增加了生成扩展属性功能. Go if object_ID('[up_CreateTable]') is not null Drop Procedure [up_CreateTable] Go /* 生成建表脚本(V4.0) Andy 2017-3-28 */ Create Proc up_CreateTable ( @objectList nvarchar(max)=null ) as --With ENCRYPTION /* 参数说明: @obj
(Sorry for that click-bait heading. Couldn't resist ;-) ) We're on a mission. To teach you SQL. But mostly, we want to teach you how to appreciate SQL. You'll love it! Getting SQL right or wrong shouldn't be about that You're-Doing-It-Wrong? attitude