Description:
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When executing multiple queries from a single mssql_query call, the connection is lost and subsequent connections cannot be created.  There are similar problems documented for PHP4, but it seems that (a) this is not documented for PHP5; and (b) the inability to create subsequent connections is not documented.  In particular, it seems the mssql_select_db is what is failing in the second connection.

Reproduce code:
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$conn = mssql_connect('host', 'user', 'pass');
mssql_select_db("db", $conn);
mssql_query("QUERY 1", $conn);
mssql_query("QUERY 2; QUERY 3; QUERY 4;", $conn);
// this will fail:
mssql_query("QUERY 5", $conn);
// this is ok
mssql_close($conn);
// everything below will fail too:
$conn2 = mssql_connect('host', 'user', 'pass');
mssql_select_db("db", $conn2);
mssql_query("QUERY 6", $conn2);

Expected result:
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The queries should execute with no problems.

Actual result:
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Everything after the multiple query mssql_query call ("QUERY 2; QUERY 3; QUERY 4;" will fail.  New connections fail when trying to select a database ("mssql_select_db() [function.mssql-select-db]: Unable to select database:...") and the existing connection cannot be used anymore ("mssql_query() [function.mssql-query]: Query failed in...") .