SQL BOOK

Below are the good good sql/plsql book.

Prepares By Oracle : SQL BOOK
Prepared By Oracle : SQL PRACTICES BOOK

Prepared By Manjunath BT : SQL BOOK
Prepared BY Tutorialspoint.com : SQL/PLSQL BOOK

If your new to SQL and PLSQL - Then go for this book : SQL/PLSQL

Duplicate rows in a table

SELECT
  Col1, Col2, COUNT(*)
FROM Table1
 GROUP BY Col1, Col2
HAVING COUNT(*) > 1

Types of SQL Statements

Below are the type of sql statement which will be most useful, while using sql. 

Thanks and Regards

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