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What is database:
database is a storage system taht has a collection of data.

Types of database:
2 types :
1RBBMS:-relational database store in form of tables, that can easily retrived, managed,and update.
2.Non-RDMS:-non relational database store data in the form document,graph.


What is Sql:-
sql is relational databse.
sql structured query language:
sql is a language to communicate with database.
sql command help you to store ,process ,analyze and manipulate database.



What is difference between sql and Nosql
sql: 1 sql  is relational database
     2.data store in tables
     3.databases have fixed or static or predefine schema.
     4.low performance with huge volumes of data.
     5.ex:-mysql,db2 , oracle,sql-server. 


nosql: 1. it is non relational database.
       2. data store in the key:value, document,graph.
       3. they have dynamic schema.
       4. Easily works with huge volumes of data
       5. exa:mongodb



4 types of sql commands:
1.Data Defination language:DDL
   create,alter,Drop,Truncate.

2. Data manipulation language:DML
    select , insert,Update,delete

3. Data control language: DCL
   grant, revoke

4. Trasaction control language:TCL
    commit, rollback


Data Types:
Datatypes of a column defines what value the column can store in table.
Data type mailty classified into three categories:
1. numeric datatype:int ,float,bool, bigint,double.
2.string datatype: char, varchar
3.date &time: date,datetime,timestamp.