How do I return the SQL data types from my query?

I've a SQL query that queries an enormous (as in, hundreds of views/tables with hard-to-read names like CMM-CPP-FAP-ADD) database that I don't need nor want to understand. The result of this query needs to be stored in a staging table to feed a report.

I need to create the staging table, but with hundreds of views/tables to dig through to find the data types that are being represented here, I have to wonder if there's a better way to construct this table.

Can anyone advise how I would use any of the SQL Server 2008 tools to divine the source data types in my SQL 2000 database?

As a general example, I want to know from a query like:

SELECT Auth_First_Name, Auth_Last_Name, Auth_Favorite_Number 
FROM Authors

Instead of the actual results, I want to know that:

Auth_First_Name is char(25)
Auth_Last_Name is char(50)
Auth_Favorite_Number is int

I'm not interested in constraints, I really just want to know the data types.

Solution 1:

select * from information_schema.columns

could get you started.

Solution 2:

For SQL Server 2012 and above: If you place the query into a string then you can get the result set data types like so:

DECLARE @query nvarchar(max) = 'select 12.1 / 10.1 AS [Column1]';
EXEC sp_describe_first_result_set @query, null, 0;  

Solution 3:

You could also insert the results (or top 10 results) into a temp table and get the columns from the temp table (as long as the column names are all different).

SELECT TOP 10 *
INTO #TempTable
FROM <DataSource>

Then use:

EXEC tempdb.dbo.sp_help N'#TempTable';

or

SELECT * 
FROM tempdb.sys.columns 
WHERE [object_id] = OBJECT_ID(N'tempdb..#TempTable');

Extrapolated from Aaron's answer here.

Solution 4:

You can also use...

SQL_VARIANT_PROPERTY()

...in cases where you don't have direct access to the metadata (e.g. a linked server query perhaps?).

• SQL_VARIANT_PROPERTY (Transact-SQL)

In SQL Server 2005 and beyond you are better off using the catalog views (sys.columns) as opposed to INFORMATION_SCHEMA. Unless portability to other platforms is important. Just keep in mind that the INFORMATION_SCHEMA views won't change and so they will progressively be lacking information on new features etc. in successive versions of SQL Server.

Solution 5:

There MUST be en easier way to do this... Low and behold, there is...!

"sp_describe_first_result_set" is your friend!

Now I do realise the question was asked specifically for SQL Server 2000, but I was looking for a similar solution for later versions and discovered some native support in SQL to achieve this.

In SQL Server 2012 onwards cf. "sp_describe_first_result_set" - Link to BOL

I had already implemented a solution using a technique similar to @Trisped's above and ripped it out to implement the native SQL Server implementation.

In case you're not on SQL Server 2012 or Azure SQL Database yet, here's the stored proc I created for pre-2012 era databases:

CREATE PROCEDURE [fn].[GetQueryResultMetadata] 
    @queryText VARCHAR(MAX)
AS
BEGIN

    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    --SET NOCOUNT ON;

    PRINT @queryText;

    DECLARE
                @sqlToExec NVARCHAR(MAX) = 
                    'SELECT TOP 1 * INTO #QueryMetadata FROM ('
                    +
                    @queryText
                    +
                    ') T;'
                    + '
                        SELECT
                                    C.Name                          [ColumnName],
                                    TP.Name                         [ColumnType],
                                    C.max_length                    [MaxLength],
                                    C.[precision]                   [Precision],
                                    C.[scale]                       [Scale],
                                    C.[is_nullable]                 IsNullable
                        FROM
                                    tempdb.sys.columns              C
                                        INNER JOIN
                                    tempdb.sys.types                TP
                                                                                ON
                                                                                        TP.system_type_id = C.system_type_id
                                                                                            AND
                                                                                        -- exclude custom types
                                                                                        TP.system_type_id = TP.user_type_id
                        WHERE
                                    [object_id] = OBJECT_ID(N''tempdb..#QueryMetadata'');
            '

    EXEC sp_executesql @sqlToExec

END