by Dexter | Jan 6, 2021 | Oracle SQL
In this tutorial, we will learn what are indexes and how they are used and created in Oracle. We might have noticed an index at the end of a technical book which contains all the important keywords and concepts listed alphabetically, so that we can quickly search and...
by Dexter | Jan 6, 2021 | Oracle SQL
In a correlated subquery, the inner subquery refers to an object from outer query. Before we understand the concept behind correlated subquery, lets revisit the concept of subquery by seeing this example: SELECT * FROM employees WHERE salary > (SELECT salary FROM...
by Dexter | Jan 6, 2021 | Oracle SQL
A Subquery is a SELECT statement which is used inside other SELECT statement. It can also be used inside INSERT, UPDATE or DELETE statements. A Subquery can be placed inside either WHERE, FROM or HAVING clause after SELECT statement. Syntax: SELECT Column1, Column2,...
by Dexter | Jan 6, 2021 | Oracle SQL
What is a Sequence? A Sequence is an Oracle Database Object that we create to generate numeric(integer) values. Often while working with Tables in Oracle database with Primary key constraint, we need to insert a new row into a table and manually input the primary_key...
by Dexter | Jan 5, 2021 | Oracle SQL
We have seen UNION, UNION ALL and INTERSECT set operators till now and MINUS is the final set operator in Oracle. MINUS Set operator is used for returning rows that are present in the first query which are absent in second query. Syntax: The syntax of MINUS set...
by Dexter | Jan 5, 2021 | Oracle SQL
The Oracle INTERSECT operator is used for finding the intersection of results of two queries. Syntax: The syntax of Oracle INTERSECT set operator is as follows: SELECT column1, column2, column_n … FROM Table1 INTERSECT SELECT column1, column2, column_n …...
