sql-server - SQL server ERROR 列名不明确

Question

无法理解此 SQL 查询中有什么问题:

USE [My_db]
GO

SELECT ItemId
      ,Subject
      ,CreatedOn
  FROM ItemBase AS e
      INNER JOIN ItemExtensionBase AS p
      ON e.ItemId = p.ItemId
GO

错误:

 Msg 209, Level 16, State 1, Line 4
 Ambiguous column name 'ItemId'.

ItemId 列存在于两个表中。

Answer 1

USE [My_db]
GO

SELECT e.ItemId
      ,Subject
      ,CreatedOn
  FROM ItemBase AS e
      INNER JOIN ItemExtensionBase AS p
      ON e.ItemId = p.ItemId
GO

您需要告诉它从哪个表中获取 itemid 字段