通过WHERE子句传递SQL存储过程的整体

Question

I have a SQL stored procedure of the form

SELECT [fields] FROM [table] WHERE @whereSql

I want to pass the procedure an argument (@whereSql) which specifies the entire WHERE clause, but the following error is returned:

An expression of non-boolean type specified in a context where a condition is expected

Can this be done?

Answer 1

The short answer is that you can't do it like this -- SQL Server looks at the contents of a variable as a VALUE. It doesn't dynamically build up the string to execute (which is why this is the correct way to avoid SQL injection attacks).

You should make every effort to avoid a dynamic WHERE as you're trying to do, largely for this reason, but also for the sake of efficiency. Instead, try to build up the WHERE clause so that it short-circuits pieces with lots of ORs, depending on the situation.

If there's no way around it, you can still build a string of your own assembled from the pieces of the command, and then EXEC it.

So you could do this:

DECLARE @mywhere VARCHAR(500)
DECLARE @mystmt VARCHAR(1000)
SET @mywhere = ' WHERE MfgPartNumber LIKE ''a%'' '
SELECT @mystmt = 'SELECT TOP 100 * FROM Products.Product AS p ' + @mywhere + ';'
EXEC( @mystmt )

But I recommend instead that you do this:

SELECT TOP 100 * 
    FROM Products.Product AS p 
    WHERE 
        ( MfgPartNumber LIKE 'a%' AND ModeMfrPartNumStartsWith=1)
    OR  ( CategoryID = 123 AND ModeCategory=1 )

Answer 2

I believe this can be done using Dynamic SQL. See below:

CREATE PROCEDURE [dbo].[myProc]
@whereSql nvarchar(256)

AS
    EXEC('SELECT [fields] FROM [table] WHERE ' + @whereSql)
GO

That said, you should do some serious research on dynamic SQL before you actually use it. Here are a few links that I came across after a quick search:

• http://www.sommarskog.se/dynamic_sql.html

• http://msdn.microsoft.com/en-us/library/aa224806%28SQL.80%29.aspx

• http://www.itjungle.com/fhg/fhg100505-story02.html

Answer 3

Make sure you read this fully

www.sommarskog.se/dynamic_sql.html

Answer 4

Dynamic SQL listed in some of the Answers is definitely a solution. However, if Dynamic SQL needs to be avoided, one of the solutions that I prefer is to make use of table variables (or temp tables) to store the parameter value that is used for comparison in WHERE clause.

Here is an example Stored Procedure implementation.

CREATE PROCEDURE [dbo].[myStoredProc]
@parameter1 varchar(50)
AS

declare  @myTempTableVar Table(param1 varchar(50))
insert into @myTempTableVar values(@parameter1)

select * from MyTable where MyColumn in (select param1 from @myTempTableVar)

GO

In case you want to pass in multiple values, then the comma separated values can be stored as rows in the table variable and used in the same way for comparison.

CREATE PROCEDURE [dbo].[myStoredProc]
@parameter1 varchar(50)
AS

--Code Block to Convert Comma Seperated Parameter into Values of a Temporary Table Variable
declare  @myTempTableVar Table(param1 varchar(50))
declare @index int =0, @tempString varchar(10)

if charindex(',',@parameter1) > 0
begin
 set @index = charindex(',',@parameter1)
 while @index > 0
  begin
    set @tempString = SubString(@parameter1,1,@index-1)
    insert into @myTempTableVar values (@tempString)
    set @parameter1 = SubString(@parameter1,@index+1,len(@parameter1)-@index)
    set @index = charindex(',',@parameter1)
  end

  set @tempString = @parameter1
  insert into @myTempTableVar values (@tempString)
end
else
insert into @myTempTableVar values (@parameter1)

select * from MyTable where MyColumn in (select param1 from @myTempTableVar)

GO

Answer 5

http://sqlmag.com/t-sql/passing-multivalued-variables-stored-procedure

try this it works!!

CHARINDEX (',' + ColumnName + ',', ',' +
REPLACE(@Parameter, ' ', '') + ',') > 0

execute syntax set @Parameter= 'nc1,nc2'