Dear all，
Our application will be switched from SQL Server to PostgreSQL.
However, a few functions are not supported yet. So we decided to extend it.
The functions are as following:
1. CHARINDEX
2. Operator +
3. CONVERT
The extended functions are almost completed but your opinion is very important to us.
Would you please help us to review the extended source?
The attachments is the diff source.
Thank you very much.
Best wishes~
Sincerely yours, rohto.david
