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Database Creation & Table Manipulations

Database Creation & Table Manipulations

 /*creating a database*/

create database school;

/*show list of databases*/

show databases;

/*to delete a database*/

drop database school;

/*getting into a database school*/

use school;

/*creating a table info

Name Roll Section Subject

*/

create table info(

name varchar(255),

roll int,

section varchar(1),

subject varchar(25)

);

/*to show list of tables present inside school database*/

show tables;

/*to show the structure of table*/

desc info;

/*to add a new column*/

alter table info add column house varchar(255);

/*to add a class column after roll number*/

alter table info add column class int after roll;

/*to add checking to class column*/

alter table info change column class class int check(class>0 and class<13) not null;

/*to add primary key to class roll*/

alter table info change column roll roll int primary key;

/*adding a default value to house set house to white house*/

alter table info change column house house varchar(10) default "White";

/*inserting data into table info*/

insert into info(name,roll,class,section,subject,house) values("Ram",1,2,'A','English','Green');

/*to show the data present in the info table*/

select *  from info; /*  * means all  */

/*for multiple entries*/

insert into info(name,roll,class,section,subject,house) 

values("Adam",2,2,'A','English','Green'),("Sam",3,2,'D','History','Green'),("Ajay",4,2,'C','English','Green'),

("Srishti",5,2,'C','Science','Green'),("Souvik",6,2,'B','GK','Green');

/*to delete a entry*/

delete from info where roll=3;

/*to update section of Adam to Section D*/

update info set section='D' where roll=2;

/*to display the names of the students who name begins with S*/

select * from info where name like 'S%';

/*to display the name of the students who has letter a in between the word*/

select * from info where name like 'S%';


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