SQL Server*=运算符？

Question

今天,在客户端的生产系统中,我发现了一个包含不熟悉语法的SQL Server查询.在下面的例子中,*=运营商做了什么？我在MSDN上找不到它.查询执行并返回数据.据我所知,自从他们使用SQL Server 2000以来,它一直存在于系统中,但它们现在正在运行2005.

declare @nProduct int
declare @iPricingType int
declare @nMCC int

set @nProduct = 4
set @iPricingType = 2
set @nMCC = 230

--Build SQL for factor matrix

Select distinct
base.uiBase_Price_ID,
base.nNoteRate, 
base.sDeliveryOpt, 
IsNull(base.nPrice,0) as nPrice, 
IsNull(base.nPrice,0) + Isnull(fact.nFactor,0) as nAdjPrice, 
base.iProduct_ID,
fact.iPosition as fiPosition, 
base.iPosition, 
CONVERT(varchar(20), base.dtDate_Updated, 101) + ' ' + CONVERT(varchar(20), base.dtDate_Updated, 108) as 'dtDate_Updated', 
fact.nFactor, 
fact.nTreasFactor, 
product.sProduct_txt ,  
pfi.sPFI_Name,  
mccprod.nServicing_Fee,  
fact.nNoteRate as fNoteRate,  
mcc.nLRA_Charge as nLRA  
From 
tbl_Base_Prices base, tbl_Factors fact, tbl_Product product, tbl_PFI pfi, tbl_MCC mcc, tbl_MCC_Product mccprod 
Where
base.iProduct_ID = @nProduct  
And base.iProduct_ID *= fact.iProduct_ID 
And base.iPosition *= fact.iPosition 
And base.nNoteRate *= fact.nNoteRate 
And base.iPricing_Type = @iPricingType
And fact.iMCC_ID =  @nMCC
And fact.iProduct_ID = @nProduct
And mcc.iMCC_ID =  @nMCC 
And mcc.iPFI_ID = pfi.iPFI_ID 
And mccprod.iMCC_ID =  @nMCC
And mccprod.iProduct_ID =  @nProduct
And base.iProduct_ID = product.iProduct_ID 
and fact.iPricing_Type= @iPricingType
Order By
base.nNoteRate, base.iPosition 

Answer 1

立即删除此代码并替换为左连接.此代码并不总是正确解释(有时SQL Server决定它是交叉连接),即使在SQL Server 2000中,因此可能会给出错误的结果!此外,它已被弃用.

我要补充一点,在调整左连接时,你应该删除所有其他隐式连接.自1992年以来,隐式连接语法已经过时,没有任何借口仍然存在于生产代码中.混合隐式和显式连接可能会产生意外结果.

Answer 2

它是左外连接,=*是右外连接.

例如以下是平等的;

  SELECT * FROM Table1 LEFT OUTER JOIN Table2 ON Table1.ID = Table2.FK_ID

  SELECT * FROM Table1, Table2 WHERE Table1.ID *= Table2.FK_ID

Answer 3

外连接(*=和=*)的非ANSI语法位于将在下一版本的SQL中删除的已弃用功能的官方列表中.

下一版本的SQL Server将不支持以下SQL Server数据库引擎功能.请勿在新的开发工作中使用这些功能,并尽快修改当前使用这些功能的应用程序.

替换功能是JOIN的ANSI兼容语法.

Answer 4

这是一种速记连接语法.看看这个涉及这个主题的线程.

Transact-SQL速记连接语法？