dynamic sql and sql_variant

Posted on 2007-12-05
Last Modified: 2010-03-19
it isn't liking me concatening the sql_variant... in my app i have a dropdown list of fields, and they are tagged with their sqldbtypes... and i got everything handled over there if i can get this part of the query working...  i'm not sure i can just cast the sql_variant to an nvarchar and the query will still work as i expect it to...   i hope it will work for fields that are bits, ints, datetimes, nvarchars, etc....  

As you can guess... @value is the sql_variant...

            Set @command =
                  'Select Row_Number() Over(ORDER BY nameCompany) as Row,
            Into #Temp
            From Company
            Where ' + @fieldName + '= ' + @value;


Question by:picsnet
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LVL 25

Expert Comment

ID: 20417355
just put an explicit cast in there to nvarchar
LVL 25

Expert Comment

ID: 20417358

            Where ' + @fieldName + '= ' + cast(@value as nvarchar(100));

100 or as large as you need it to be

Author Comment

ID: 20417590
will that not change the meaning if @value is a datetime, or int, or float, etc....
LVL 25

Accepted Solution

imitchie earned 500 total points
ID: 20417607
It finally clicks... then your dynamic SQL is incorrect from the start.
If @value is a string, say 'ABC', then the generated SQL is

                  Select Row_Number() Over(ORDER BY nameCompany) as Row,
            Into #Temp
            From Company
            Where addrLine1 = ABC

Can you see the problem? ABC is not in quotes, and will cause an error.  Try this instead.

            Where ' + @fieldName + '= ''' + replace(convert(nvarchar(100), @value), '''', '''''') + '''';

Expert Comment

ID: 20418343

if you assign a variable
 @value = ''' + cast(@value as nvarchar(100)) + ''''

and then use it in your may work

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