Learn SQL Script/ PL SQL

Hi SQL Experties,

I Have gone throw following documents:

1. HA150

2. Help.sap material (SAP_HANA_SQL_Script_Reference_en)

I want to learn advance SQL, SQL Script, and PL/SQL in-depth.

Could you please provide me good documents or links where i can find proper material for learning SQL stuff.

Thanks,

Kuldeep Jain