Let say you have the following data in you database table t1 and you want to select the IDs for the row record that have the same value on COL1 and COL2. ID   COL1   COL2   COL3 ====================== 1    100    200    300 2    200    300    400 3    100    200    500 4    300    300    300 5    200    300    400 And the expected result is ID = 1,2,3,5. The SQL to … [Read more...]

One may find that using SQL's LIKE clause in Java PreparedStatement is not straight forward. There is no documentation on how the LIKE clause should be used when it is used with the PreparedStatement object. Thus, most of the programmer would rather use the full SQL to execute the statement. … [Read more...]

Most programmers may already know the main different between CHAR and VARCHAR - The first one supports fixed-length data and the second one supports variable-lengths of data. Some people may think, since VARCHAR can do what CHAR does, then why we still need CHAR in our database design. I even have heard one of the very experienced Oracle database administrator say "Nowadays … [Read more...]