SQL Tutorial for Beginners

This SQL (Structured Query Language) Tutorial provides an insight into various PLSQL commands with examples. SQL is used to access and manipulate data in databases like MySQL, SQL Server, Oracle, Sybase, DB2 etc. Hope this tutorial will help the beginners to understand SQL better.

Primary Key, Foreign Key and Unique Key

To understand the ordering of data inside a table, one had to be thorough about database keys.This article will provide an insight into Primary Key, Foreign Key and Unique Key.

SQL Operators - Where, IN, AND, OR and Between

We have learned basic DML operations in the last article. Now it's time to learn filter commands like Where, IN, AND, OR, Between etc. which can be used to filter data retreived from a table.

SQL Like and Distinct Command

In this article, we will look into the Like command which is used for wild card filtering of data from a table, when used in different positions with the help of examples. Primary objective of distinct command is to fetch unique values from a given table.

SQL Group By and Having Command

Learning SQL won't be complete without knowing the usage of "Group By" and "Having" clause. These commands are one of the most commonly used one is SQL queries and knowing when and how to use them make your life easy.

Difference between having and where clause

Where clause can be applied to a single row, where as Having clause is applied to the whole group. But, it does not mean that we cannot have both Where and Having clause in a single query. If both where and having clauses are used together in single a query, where clause will apply filter condition to the list of records and it will filter the group of records from the table and Having clause will be applied to this resultant group and groups which meets the condition given in having clause will be filtered in the resultant table.

Difference between Inner join and Left join

SQL Join is used for combining the rows between two or more tables using common fields/columns between these tables in a relational database. The goal of joining table is to extract the meaningful list of data. Joins will be obtained from the term called predicate. “Join” is a term used to combine fields of two or more tables by using common values between the tables.

Clustered Index vs Non Clustered Index

In SQL database, there are two different types of indexing and those are – “Clustered Index” and “Non Clustered Index”. Before going to this topic let’s discuss about indexing in database.

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