Structured Query Language (SQL)
For companies and businesses, there are various ways used for keeping records, and creating a database for them is one of such ways. Prior to the creation of the Structured Query Language (SQL), databases had very complex programming interfaces. The design of the database was in regard to a network structure called Committee on Data Systems Languages (Codasyl), Codasyl’s creation was a contributory factor for the creation of the programming language called “Cobol,” and other language extensions for databases.
SQL is a programming language used for creating, managing, and manipulating data and database systems, and this invariably means that SQL is applied to the modification, update, query, and insertion of data. A lot of relational databases can be used with SQL, and that gives database administrators (DBAs) some advantages because it is a requirement that databases are supported on various platforms.
In 1970, Dona Chamberlin and Raymond Boyce, both of IBM, created SQL, and it was not released commercially until 1979 by Oracle Corporation (then it was called Relational Software Incorporated). At the moment, there are different versions of SQL, all vendor-compliant, voluntary, and supervised by the American National Standards Institute (ANSI). There are also proprietary versions by some vendors that are incorporated and created based on ANSI SQL, and some of them include Transact SQL by Microsoft, SQL+ by Oracle, etc.
Becoming a SQL professional is one of the most important rites needed for becoming a DBA, and when learning to become one, the journey begins with being able to write the SQL script without the use of a graphical user interface (GUI). Presently, database management has become easier, with the introduction of easy-to-use GUIs and drag-and-drop structures. However, regardless of the tools created to make database management easy, it is important to learn everything there is to know about SQL because the tools created to make data management process easy are not as potent as SQL.
There are four main categories attributed to the SQL code, and they are:
- Data Definition Language (DDL)
This is applied when managing index structures and tables. With this code, the SQL programmer Can apply DDL statements such as DROP, TRUNCATE, ALTER, and CREATE.
- Queries
This is usually performed by applying the familiar SELECT statement, which is subdivided into different clauses like SELECT, ORDER BY, WHERE, and FROM.
- Data Control Language (DCL)
The DCL is applied when trying to revoke or assign database permissions and rights, and thus the main statements used in this code are REVOKE and GRANT.
- Data Manipulation Language (DML)
Applying the DML translates to adding, updating or deleting data. The DML is a subset of the SELECT statement: UPDATE, DELETE, and INSERT are the statements used. Also, there are other control statements used, including SAVEPOINT, ROLLBACK, BEGIN TRANSACTION, and COMMIT
Having knowledge about database management is not the same as being knowledgeable about SQL, as it comes with its own certification, and a greater percentage of organizations and companies employ the SQL database management system.
Course Overview
Introduction to SQL:
- Functions
- Categories of Commands
- Joins
- Subqueries: Learn how to fetch data, depending upon indirect conditions.
- Constraints
- Database Objects
- Views
- Indexes
- Synonyms
- Sequence
- Tables.
