Retrospective of SQL – geeksforjobs

 

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SQL

  • Structured query language is a language that provides an interface to the relational database system
  • SQL is developed by IBM in 1970.
  • To deal with the database objects below we need a programming language called SQL
  • Plan
  • The table
  • opinion
  • The list
  • Synonym / alias
  • The scenery
  • The trigger
  • UDF
  • stored procedures
  • Database app object

DDL (Data Definition Language)

  1. Create: Used to create a table in a database
  2. Alert: modify existing table
  3. Drop: Drop table with table structure

DML (data manipulation language)

  1. INSERT: insert data into table
  2. Select: To retrieve data from the table
  3. Update: update existing data
  4. DELETE: to delete data from a table

DCL (Data Control Language)

  1. Grant: Used to grant access / select / insert / delete
  2. Review: Used to revoke provided access

Bandhan (Transaction Control Language)

  1. COMMIT: to save work done
  2. Rollback: Restoring the database to its original state since the last state
  3. SQL DT: Specify the type, size, and format of the data

Barrier Type with Description:

Name of constraint Table level description
not null Column level Restrict a column
Unique Table level Checks whether a column
Is unique among all rows in a table
Restriction

Default constraintt: It is used to insert a default value in a column, if no other value is specified at the time of insertion.

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