Important Concepts in SQL

In this section you will find Important concepts related to SQL.
The concepts are divided in three parts:

  • Standard SQL - Important Concepts

  • SQL Server Analysis Services (SSAS) - Important Concepte

  • SQL Server Integration Services (SSIS) - Important Concepts

 
 

Standard SQL - Important Concepts

  • There are four main categories which one usually divide Standard SQL into, which are:

    • Data Query Language (DQL)

      • Perform queries towards the underlying data, which includes a SELECT clause

      • Examples: SELECT Country FROM Geography

    • Data Definition Language (DDL)

      • Perform Operations on a specific database

      • Examples: CREATE, DROP, ALTER, TRUNCATE

    • Data Manipulation Language (DML)

      • Perform Manipulation of data in a database

      • Examples: INSERT, UPDATE, DELETE

    • Data Control Language (DCL)

      • Deals with rights and permission to specific data

      • Examples: GRANT, REVOKE

    • RDBMS stands for Relational DataBase Management System

    • DBMS stands for DataBase Management System

    • DBMS is the overall term

    • RDBMS is a subset of a DBMS which stores data in a specific way with different rules set on the relation between the different Relations in the DBMS.

  • Some of the most common clauses in the SELECT statement are:

    • FROM

    • JOIN

    • WHERE

    • GROUP BY

    • ORDER BY