What would happen if I set null in prepared statement with varchar always?

Question

I have this method to insert data using jdbc that will insert the value according to the java type. Something like this:

Object o = map.get( key );

if( o == null ) {
    // setNull( index );
} else  if( o instanceof String ) {
    // setString( index, (String) o );
} else if( o instanceof Timestamp ) {
    // setTimestampt( index, ( Timestamp ) o );
} else if( o instanceof Integer ) {
    // setInt( index, (Integer) o );
}
    index++;

It has a problem though ( beside it is all commented :P )

If the value of o is null, I'm requiered to use "setNull(int, int)" method, but I have to specify the SQL type:

...Note: You must specify the parameter's SQL type.

But... I don't know the type, so I'm considering use always VARCHAR ( just because )

setNull( index,Types.VARCHAR); .

What would happen if I set null in prepared statement with varchar always?

I'm using:

Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

With Oracle JDB driver:

11.1.0.7.0-Production ( ojdbc6.jar )

What would be an alternative?

Answer 1

Could you not interrogate the database and get the column type via the ResultSetMetaData interface?