使用来自html表单的NULL填充SQL查询

Question

I have an html page with a form that contains a couple of selectors.

The form is processed by GET via a js function that uses jquery ajax to send the data to a php page. The php builds the TSQL query to select the information.

If you don’t choose any option in the selectors I need a NULL in my query. Both in the js and php page I’ve tried with:

if($variableFromSelector1 ==’-’){ $variableFromSelector1 =’NULL’;}
if($variableFromSelector2 ==’-’){ $variableFromSelector2 =’NULL’;}

(the – means nothing chosen in the selector)

But this fills the query with ‘NULL’ which is not the same as NULL

Here's how the query goes:

   function showData($variableFromSelector1,$variableFromSelector2)
    {  

            $strSqlSelect = "EXECUTE mybd.dbo.myprocedure 
            @var1='".$variableFromSelector1."',
            @var2='".$variableFromSelector2."'";
    }

How can I get the query with NULL in case no option is chosen in the selector?

Thanks a lot

Answer 1

if($variableFromSelector1 ==’-’){ $variableFromSelector1 = NULL;}
if($variableFromSelector2 ==’-’){ $variableFromSelector2 = NULL;}

function showData($variableFromSelector1,$variableFromSelector2)
{  
  $var1 = is_null($variableFromSelector1) ? 'NULL' : "'{$variableFromSelector1}'";
  $var2 = is_null($variableFromSelector2) ? 'NULL' : "'{$variableFromSelector2}'";

  $strSqlSelect = "EXECUTE mybd.dbo.myprocedure 
  @var1=".$var1.",
  @var2=".$var2;
}

Also remember to sanitize all inputs to protect against SQL-injection.