Improving limit method using LIMIT,OFFSET

[ushiday]

To improve #391 , I would like to suggest a code that uses LIMIT,OFFSET. This method is supported in recent DB2 versions, is consistent with other database software, and is simple.
However, this method is not available to older version DB2 users. (I think I'm in the minority now...)

[alanseiden]

@ushiday Thank you for posting these fixes. I prefer the LIMIT and OFFSET approach as a more modern one that is easier to understand.
Observations:

• LIMIT and OFFSET have been available in IBM i Db2 since 2016 with IBM i 7.1 TR11 and IBM i 7.2 TR3.
• The oldest supported operating system release is now IBM i 7.3.
• ZF1-Future was created to help people upgrade to new versions of PHP. Those new PHP versions could not run on IBM i 7.1 and older anyway.
• Anyone running an old OS without LIMIT and OFFSET can stay with their old ZF1 version.

[develart-projects]

Any possibility to add DB version check, please? Any not backward compatible changes are a bit harder to approve.
If we can split the logic, based on the DB version, we are good to go imo.

[alanseiden]

We should find out when LIMIT+OFFET were added to LUW (Linux/Unix/Windows) Db2 as well.

[ushiday]

If it is necessary to take into account the DB2 old version, Improving limit method using OVER() #392
Is that a better solution?

[develart-projects]

Still thinking about this one. I have no idea about DB2, but still. I can feel the pain of some older corporate (hi banks) DB system admins, trying to upgrade and start to fail DB stuff. That's why I'm asking, if there is any possibility to split codebase, based on the connection/driver/etc. If not, I would most probably suggest to go forward with older approach.