SQL Basics


Structured Query Language

SQL is a structured query language. It is a non-procedure language that allows built-in function and command for controlling the database and its data. It provides built-in syntax to define the express for controlling the database. The application of database like SQL server Oracle, my SQL etc support this language to generate the queries and its processing. It provides queries expression to manage the database structure and also controlling the networking processor for the database.

This language introduces by Oracle Corporation as commercially in 1979. In 1986 this standard language publishes by ANSI(American National Standard Institute) and ISO(International standard organization). This language completely uses in 1989 with commercials and professional use.

The organization uses SQL in1982 for database processing it supports schema define variable temporary table operators standard error etc. This language helps users to create delete etc operation with an existing database. It supports string, numeric, date or other datatype related function for handling the database table. It also to manage set of command as programming instructions and execute together.

Types of SQL languages

Iterative SQL->

It is a type of SQL that allows managing the data table and its processing directly on the database and produce output at the command prompt. In this SQL we can define the command at command prompt get instant output.

Embedded SQL->

It is also the type of SQL that allows managing the command with the help of particular computer language java, c++, etc with define the SQL command into programming instruction and execute similar as a program for database control.

SQL Datatypes

The datatype is used to define the nature of particular field for storing the information SQL provide built-in datatype to maintain the column and its datatype in relational database system the relation are managed on the base of data and it’s datatype to identify a column data contain which type information.

There are following datatype:-

Char-> It is datatype that allows storing character value in the particular field. It stores 0 to 55 character.

Varchar->It is also used for character value with a maximum length up to 2000 character. We also use var char2 datatype for alphanumeric.

Long->It is datatype that uses for character information with huge information up to 2 GB. It is basically used to store a description of database or other big information. THE long datatype cannot be indexed(sort), execute queries and apply function a table can contain only one long datatype.

Number->It is used to store a numeric value into the field. In this with define size of numeric data as floating also.

Date->It is datatype that allows storing date related information as dd mm yy format.

Type of SQL command

The SQL provides a built-in command to manage the data record and manipulate data table. The SQL command is categories different part of the base of command processing.

commands in SQL


DDL(Data definition languages)

It is part of SQL  command that consists of through preparation relation to the structure of object like a table, index, view, etc. In this command, we create drop alter etc, processing of the particular object.

DML(Data manipulation language)

This part of SQL  command manages tables on the base of its value. The data can process like getting information from the data table, manipulation of data for executing functions full stop it also helps to update the record form particular condition. It supports retrieving data manipulation and updating data from the database.

DCL(Data control language)

This part SQL command allows us to control the records for security purpose. DCL consist of feature that determines whether the user is permitted to perform a particular action on the existing table. It supports grant an revoke permission to the user.



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Pulkit Wadhwa

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