在SQL Server 2000中，此操作数(* = star-equals)是什么? [英] What is this operand (*= star-equals) in SQL server 2000?

问题描述

我有一个查询，该查询是从ms sql 2000中提取并插入MySql查询中的.它不起作用，MySql将使* =运算符阻塞.在此示例中，我有两个名为person_name的varchar列.

I have a query that I pulled from ms sql 2000 and plugged into a MySql query. It did not work, MySql would choke on the *= operator. In this example I have two varchar columns called person_name.

SELECT * FROM tbl1 a, tbl2 b 
WHERE a.id = b.id
AND a.person_name *= b.person_name

我用其他语言知道myInt * = myTotal也可以读作myInt * myInt = myTotal.但是，我正在使用包含所有字符，没有整数的varchars.我把它写成这样:

I know in other languages myInt *= myTotal could also be read as myInt * myInt = myTotal. However, I'm working with varchars that contain all chars, no integers. I wrote it out like:

AND a.person_name * a.person_name = b.person_name

Voila！它似乎起作用了.有人可以解释发生了什么吗? * =运算符是将char转换为等效的整数还是?为什么我在网络上的任何地方都找不到该运算符?

Voila! It appears to have worked. Can somebody explain what is happening? Is the *= operator converting the chars to their integer equivalents or? And why couldn't I find this operator anywhere on the web?

推荐答案

在SQL 2000中，它用作左外部联接

In SQL 2000 this was used as a LEFT OUTER JOIN

= *是正确的外部联接

=* is a RIGHT OUTER JOIN

您的查询可能是:

SELECT 
  * 
FROM 
  tbl1 a LEFT OUTER JOIN tbl2 b ON a.person_name = b.person_name
WHERE 
  a.id = b.id

此处:

使用 非标准产品专用语法 和WHERE子句. * =运算符 用于指定左外部连接 和= *运算符用于指定 正确的外部联接.

Specifies an outer join using the nonstandard product-specific syntax and the WHERE clause. The *= operator is used to specify a left outer join and the =* operator is used to specify a right outer join.

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