假如有两张表A、B A中有两列数据,列名分别是BH1、201005(列201005为空) B中有两列数据,列名分别是BH2、ggg(列ggg中有值) A中BH1等于B中BH2时,要使A中201005取B中ggg的值,如何实现? SQL code: update a set a.[201005]=b.ggg from b where a.bh1=b.bh2
update A set [201005]=ggg from B WHERE BH1=BH2 SQL code: update a set [201005]=n.ggg from a,b where a.bh1=b.bh2
select A.BH1,B.ggg from A,B where A.BH1=B.BH2 up! 为什么 SQL code: --> 生成测试数据表: [a] IF OBJECT_ID('[a]') IS NOT NULL DROP TABLE [a] GO CREATE TABLE [a] ([BH1] [nvarchar](10),[201005] [nvarchar](10)) INSERT INTO [a] SELECT '001',NULL UNION ALL SELECT '002',NULL
--> 生成测试数据表: [b] IF OBJECT_ID('[b]') IS NOT NULL DROP TABLE [b] GO CREATE TABLE [b] ([BH