More About SQL

In this post, We will be knowing about databases, types and basic syntax of SQL.

What is Database. A database is a collection of valid and structured data stored in System.

What is RDBMS- RDBMS stands for Relational Database Management System. The term Relational Stands for data is stored in System in the form of Rows and Columns.

Database Systems - There are various database Systems such as MYSQL, SQL server, Oracle which is used to stored , manipulate and maintain data.

What is a Table- a table is a collection of rows and columns in which data is stored.

For exercise purpose , We will be considering below table Named Detail

ID	Name	City
1	Raj	Mumbai
2	Rahul	Nashik
3	Saurabh	Nagar

The Basic Commands Syntax in SQL.

SELECT - used to retrieve records from database.

Syntax

select column_name from table_name

Example

select Name from Detail. -will display all names from Detail table.

If you want to select all the columns then you can use "*"

select * from Detail -will display all rows and columns from Detail Table.

INSERT - used to Insert records into database.

Syntax -

INSERTinto table_name (column name_1,column_name_2)
values (value_1,value_2)

Example -

Insert into Detail (ID,Name,City) values(3, 'Rajendra', 'Thane')

If you are inserting values in all columns then you can eliminate column names

Insert into Detail values(5, 'Gaurav' 'Nashik')

Using DISTINCT - if you want to retrieve unique values from some column of a table , then it can be achieved by using DISTINCT

Syntax

select DISTINCT column_name from table_name