Question

I am writing a query that uses the CONTAINSTABLE function. For the third parameter in the CONTAINSTABLE call, I obtain the search term from a UDF. If I store the output of this UDF in a local variable and then pass the variable to the CONTAINSTABLE function, it works fine:

declare @temp nvarchar(255) = dbo.udf_GenerateTerm()
select *  FROM ContainsTable([TableToSearch], Content, @temp, LANGUAGE 1033)

However, if I directly reference the UDF as a CONTAINSTABLE argument, I get a syntax error:

select * FROM ContainsTable([TableToSearch], Content, dbo.udf_GenerateTerm(), LANGUAGE 1033)

Is there any way around this, or this this a limitation of SQL Server?

Thanks.

Answer 1

This is a limitation of the SQL Server CONTAINSTABLE operation.
Here is the grammar for CONTAINSTABLE.

CONTAINSTABLE ( table , { column_name | ( column_list ) | * } , ' <contains_search_condition> ' 
     [ , LANGUAGE language_term] 
  [ , top_n_by_rank ] 
          ) 

contains_search_condition is the part we are interested in. The grammar is defined thus

<contains_search_condition> ::= 
    { <simple_term> 
    | <prefix_term> 
    | <generation_term> 
    | <generic_proximity_term> 
    | <custom_proximity_term> 
    |  <weighted_term> 
    } 
    | { ( <contains_search_condition> ) 
    { { AND | & } | { AND NOT | &! } | { OR | | } } 
     <contains_search_condition> [ ...n ] 
    }

simple_term is made up of a word. A word is defined as

Is a string of characters without spaces or punctuation.

You can review the MSDN documentation on CONTAINS and CONTAINSTABLE for more info.