Statement.getUpdateCount() throws SQLException after getResultSet() for SELECT statements #205

zhicwu · 2025-04-27T03:11:16Z

I got the following exception when calling Statement.getUpdateCount() after getResultSet() for SELECT statements:

Exception in thread "main" java.sql.SQLException: Prepare something first
	at org.duckdb.DuckDBPreparedStatement.getUpdateCountInternal(DuckDBPreparedStatement.java:402)
	at org.duckdb.DuckDBPreparedStatement.getUpdateCount(DuckDBPreparedStatement.java:414)
	at io.github.jdbcx.driver.WrappedStatement.getMoreResults(WrappedStatement.java:354)
	at io.github.jdbcx.Main.execute(Main.java:320)
	at io.github.jdbcx.Main.executeQueries(Main.java:350)
	at io.github.jdbcx.Main.process(Main.java:411)
	at io.github.jdbcx.Main.main(Main.java:468)

Could you please enhance the driver to align with the JDBC specification and return -1 from Statement.getUpdateCount() (and similarly getLargeUpdateCount) when "the result is a ResultSet object or there are no more results"?

The text was updated successfully, but these errors were encountered:

This change implements a group of `Large` methods, like `executeLargeUpdate`, that were added in Java 8 (JDBC 4.2). Testing: existing prepared statement tests are moved to a separate file and updated to cover all `Large` methods. Fixes: duckdb#205

staticlibs · 2025-05-02T13:41:10Z

@zhicwu

Thanks for the report! I wonder if you are calling getUpdateCount() on "unitialized" statement (before running the query)? Because the following returns -1 correctly both before and after reading the ResultSet:

try (Connection conn = DriverManager.getConnection("jdbc:duckdb:");
     Statement stmt = conn.createStatement()) {
    stmt.execute("SELECT 42");
    try (ResultSet rs = stmt.getResultSet()) {
        System.out.println(stmt.getUpdateCount());
        while (rs.next());
        System.out.println(stmt.getUpdateCount());
    }
}

About getLargeUpdateCount - this is a valid concern, this (along with other Large methods) should be fixed by #207.

zhicwu · 2025-05-02T14:06:28Z

Hi @staticlibs, thank you for the reply. While the statement should indeed be initialized beforehand, my point was about the potential state of the underlying statement at the moment getMoreResults() is called, as shown in the code below:

@Override
public boolean getMoreResults() throws SQLException {
    final boolean hasMore = stmt.getMoreResults(); // <-- this could be the trigger of the exception
    queryResult.reset();
    // getResultSet() succeed while a subsequent call to getUpdateCount() fails
    queryResult.updateAll(null, hasMore ? new WrappedResultSet(this, stmt.getResultSet()) : null,
            stmt.getUpdateCount());
    return hasMore;
}

There might be scenarios where the statement is no longer valid when attempting to retrieve the next result.

staticlibs · 2025-05-02T16:09:51Z

@zhicwu

I think you are right, there is no need to throw the exception here if it breaks client code, I will include the fix (to return -1 in this case) into #207 .

This change implements a group of `Large` methods, like `executeLargeUpdate`, that were added in Java 8 (JDBC 4.2). Testing: existing prepared statement tests are moved to a separate file and updated to cover all `Large` methods. Fixes: duckdb#205

This change implements a group of `Large` methods, like `executeLargeUpdate`, that were added in Java 8 (JDBC 4.2). Testing: existing prepared statement tests are moved to a separate file and updated to cover all `Large` methods. Fixes: #205

staticlibs mentioned this issue May 2, 2025

More prepared statement enhancements #207

Merged

staticlibs closed this as completed in #207 May 5, 2025

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