声明查询字符串的变量 [英] Declare Variable for a Query String

问题描述

我想知道MS SQL Server 2005中是否有办法做到这一点：

I was wondering if there was a way to do this in MS SQL Server 2005:

  DECLARE @theDate varchar(60)
  SET @theDate = '''2010-01-01'' AND ''2010-08-31 23:59:59'''

  SELECT    AdministratorCode, 
            SUM(Total) as theTotal, 
            SUM(WOD.Quantity) as theQty, 
            AVG(Total) as avgTotal, 
            (SELECT SUM(tblWOD.Amount)
                FROM tblWOD
                JOIN tblWO on tblWOD.OrderID = tblWO.ID
                WHERE tblWO.Approved = '1' 
                AND tblWO.AdministratorCode = tblWO.AdministratorCode
                AND tblWO.OrderDate BETWEEN @theDate
            )
 ... etc

这可能吗？

推荐答案

可以，但是需要使用动态SQL。

我建议阅读诅咒和祝福动态SQL ，然后继续...

It's possible, but it requires using dynamic SQL.
I recommend reading The curse and blessings of dynamic SQL before continuing...

DECLARE @theDate varchar(60)
SET @theDate = '''2010-01-01'' AND ''2010-08-31 23:59:59'''

DECLARE @SQL VARCHAR(MAX)  
SET @SQL = 'SELECT AdministratorCode, 
                   SUM(Total) as theTotal, 
                   SUM(WOD.Quantity) as theQty, 
                   AVG(Total) as avgTotal, 
                  (SELECT SUM(tblWOD.Amount)
                     FROM tblWOD
                     JOIN tblWO on tblWOD.OrderID = tblWO.ID
                    WHERE tblWO.Approved = ''1''
                      AND tblWO.AdministratorCode = tblWO.AdministratorCode
                      AND tblWO.OrderDate BETWEEN '+ @theDate +')'

EXEC(@SQL)

动态SQL只是一个SQL语句，在执行前由字符串组成。因此，通常的字符串连接发生。每当您要使用不允许的SQL语法执行某些操作时，都需要使用动态SQL，例如：

Dynamic SQL is just a SQL statement, composed as a string before being executed. So the usual string concatenation occurs. Dynamic SQL is required whenever you want to do something in SQL syntax that isn't allowed, like:

• 单个参数表示逗号分隔IN子句的值列表


• 表示值和SQL语法的变量（即：您提供的示例）

EXEC sp_executesql 允许您使用bind / preparedstatement参数，因此您不必担心转义单引号/ etc来进行SQL注入攻击

EXEC sp_executesql allows you to use bind/preparedstatement parameters so you don't have to concern yourself with escaping single quotes/etc for SQL injection attacks.

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