SQL: Top basic SQL queries for beginners in one blog

Hello, readers in today’s article I am going to describe the top basic SQL queries. I think this article must be useful for beginners. I write about some basic queries like Create, Drop, Alter, Select, Insert and Update, etc.

So, without wasting any time let’s start…

Create database:

For Creating a new database.

create database mydb;

Here “mydb” is the name of your database.

Drop Database:

To delete an existing database.

drop database mydb;

Use Query:

Select and use an existing database.

use mydb;

Create Table:

To create a new table within a database.

create table mytable(
id int identity(1,1) primary key,
name varchar(50) not null,
city varchar(50) not null,
);

Here “mytable” is the name of your table. “id“,”name“, and “city” are the columns of the table. Here id is a primary key constraint that defines that id is not null and unique.

Drop Table:

To delete a table from the current database.

drop table mytable;

Alter Table:

Alter table is used to modify our table. The “Alter Table” command is used to add a new column, delete an existing column, or modify an existing column of our table.

To add a new column in an existing table:

alter table mytable
add pin int not null;

The above command adds a new column for “pin” of type “integer“.

To delete an existing column from the table:

alter table mytable
drop column pin;

To change the datatype of a column in the table:

alter table mytable
alter column mobile varchar not null;

If your mobile no. is an integer type and you want to change it into a varchar type this command will work.

INSERT INTO command:

To fill the records into your created table.

insert into mytable (name, city, pin)
values ('ankit','new delhi','110059');

Use the following command if you insert more than one records in a table.

insert into mytable (name, city, pin)
values ('raj','ballia','11111'),('chirag','noida','231123');

Select Query:

Select Query used to show all the records of an existing table.

select * from mytable;

Update Query:

To update or modify an existing record in the table.

update mytable
set pin='110061'
where name='ankit';

Delete Query:

To delete the inserted wrong records from the table.

delete from mytable where id=1;

To delete all records from the table using the following command:

delete from mytable;

That’s all readers this article is only dedicated to beginners. These are some basic queries in SQL server that is necessary to know.

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