SQLServerResultSetMetaData performs checkClosed and that's causing issues

[phaninra]

Driver version or jar name

6.3.3.jre7-preview

SQL Server version

2016

Client operating system

Windows 7

Java/JVM version

"1.8.0"

Problem description

The following example can be found in the javadocs of java.sql.ResultSetMetaData

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int numberOfColumns = rsmd.getColumnCount();

I've a similar operation which uses org.springframework.jdbc.object.MappingSqlQuery<T> to execute the query and then gets hold of ResultSetMetaData object.

The call getColumnCount works fine with jTDS but not with mssql driver as SQLServerResultSetMetaData checks whether the connection is closed.

I might be missing something but could not figure it out. Thanks.

[ulvii]

Hi @phaninra ,

Just to confirm, does the issue happen only when the result set is closed before rsmd.getColumnCount();?

So repro code would be something like this?

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
rs.close()
int numberOfColumns = rsmd.getColumnCount();

[phaninra]

Yep, and I believe it's due to this - https://github.com/spring-projects/spring-framework/blob/master/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java#L670

I realize that it's Spring JdbcTemplate which is closing the ResultSet. However, is there any reason for checking if the connection has been closed inside SQLServerResultSetMetaData?

[ulvii]

According to JDBC specs, ResultSetMetaData instances that were created by a ResultSet that has been closed should still be accessible. Hence this is a deficiency in the driver. We will address the issue, please stay tuned.

[ulvii]

Fixed in #685