Description:
------------
NOTE:
This issue seems to occur in versions (atleast) 4.3.4 - 5.0.4

WORKAROUND:
Be sure to call mssql_free_result() on every result that has the potential to return multiple result sets.

PROBLEM:
When a query (stored procedure for example) returns multiple result sets, you have to call mssql_next_result() OR mssql_free_result() on the result of an mssql_query().

Failure to do so will cause subsequent mssql_next_query() or mssql_select_db() calls to fail.

ADDITIONAL NOTES:
The docs should be updated if this functionality is intended.

Sorry about the 'excessive' length of code, I figure you can handle 8 extra lines.

Reproduce code:
---------------
<?php
    /* -- Stored procedure
    CREATE PROCEDURE bug_proofOfConcept_sp
    AS
        SELECT 'Result set one' AS 'Result Set';
        SELECT 'Result set two' AS 'Result Set';
    GO
    */
    $link = mssql_connect("server", "user", "pass");
    mssql_select_db("database", $link);
    
    $rs = mssql_query("EXECUTE bug_proofOfConcept_sp");
    /* Note, it doesn't matter if you fetch from $rs */
    
    /* This is where things bomb out */
    if (!mssql_select_db("database", $link)) {
        echo "Broken, as expected.\n";
    }
    
    /* If we free the result things work fine again.
       Alternatively, you could call mssql_next_result($rs) */
    mssql_free_result($rs);
    
    // Select the database (3rd, and last time)
    if (!mssql_select_db("database", $link)) {
        echo "Everything should be working here; wtf?\n";
    }
?>

Expected result:
----------------
No output

Actual result:
--------------
Warning: mssql_select_db(): Unable to select database:  database in H:\proofOfConcept.php on line 16
Broken, as expected.