What is SQL ( Introduction to Structure Query Language ) is used to perform operations on records stored in a database. Such as updating records, deleting records, creating tables, viewing and modifying, etc.
SQL is just a query language. This is not a database. To perform a SQL query, you can install any database. For example, Oracle, MySQL, MongoDB, PostGre SQL, SQL Server, DB2, etc.
what is sql ( introduction to sql in dbms )
Structured query language is the full form of SQL.
SQL is developed for managing data in a relational database management system (RDBMS).
It is pronounced SQL or sometimes as See – Qwell.
SQL is a database language, it is used for database creation, deletion, and modifying rows, etc.
SQL is completely based on the dopant relational algebra and tuple relational.
All DBMSs such as MySQL, Oracle, MS Access, Sybase, Informix, Postgres, and SQL Server use SQL as the standard (standard) database language.
Why SQL is required
To create new databases, tables and views
To insert a record into the database
To update a record in a database
To delete a record from a database
To retrieve data from a database
What SQL does
With SQL, we can query our database in several ways using Statements like English.
The user can access data from the system by running Query in SQL.
This allows the user to describe the data.
This allows the user to define the data in the database and manipulate it when needed.
This allows the user to create and drop databases and tables.
This allows the user to create a view, stored procedure, function in the database.
This allows the user to set permissions on tables, procedures and views.
SQL follows some specific set of rules and guidelines called syntax.
SQL is not case sensitive. Usually SQL keywords are written in uppercase.
SQL statements rely on text lines. We can place a SQL statement on one or several text lines.
You can perform most actions in a database with an SQL statement.
SQL relies on relational algebra and tuple relational calculus.
SQL statements are initialized with any of the SQL commands / keywords such as SELECT, INSERT, UPDATE, DELETE, ALTER, DROP etc. and the statement ends with a semicolon (;).
Example of SQL statements:
SELECT “column_name” FROM “table_name”;
Why semicolons are used after SQL statements:
Semicolons are used to separate SQL statements. This is a standard way of separating SQL statements in a database system in which more than one SQL statement is used in a single call.
In this tutorial, we will use a semicolon at the end of each SQL statement.
These are some important SQL commands:
SELECT: It extracts data from a database.
UPDATE: This updates the data in the database.
DELETE: This deletes data from the database.
CREATE TABLE: This creates a new table.
ALTER TABLE: It is used to modify a table.
DROP TABLE: This deletes a table.
CREATE DATABASE: This creates a new database.
ALTER DATABASE: It is used to modify the database.
INSERT INTO: It inserts new data into a database.
CREATE INDEX: This is used to create an index (search key).
DROP INDEX: This removes an index.
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