This post covers how to use WHERE and DELETE in sub-queries. Useful examples to refer to quickly.
Useful string functions for smart SQL developers to write better queries. Useful to read now.
I have given three ideas to improve SQL performance in this post. Quickly you can implement in your project.
SQL Order of execution is sequence of steps. The database executes each Query in a particular order. Read more.
SQL ALTER statement you can use to add columns to existing TABLE in RDBMS. Not only TABLE you can read all database object where you can use ALTER.
Ordering the SQL result is possible by giving DESC or ASC in your query. These must be used along with ORDER BY clause. Read more.