SQL – Using Sequences Table of content Sequences in SQL are database objects that generate a sequence of unique integer values. They are frequently used in databases because many applications require that each row in a table must contain unique values and sequences provide an easy way to generate them. Sequences are a feature of […]

SQL – Handling Duplicates Table of content Sometimes, tables or result sets contain duplicate records. While in most cases, duplicates are allowed, there are situations where it is necessary to prevent duplicate records and remove them from a database table. Why is Handling Duplicates in SQL Necessary? Handling duplicates in an SQL database becomes necessary […]

SQL – Sub Queries Table of content SQL Subqueries An SQL Subquery, is a SELECT query within another query. It is also known as Inner query or Nested query and the query containing it is the outer query. The outer query can contain the SELECT, INSERT, UPDATE, and DELETE statements. We can use the subquery […]