SQL is a language to operate databases; it includes database creation, deletion, fetching rows, modifying rows, etc

What is SQL?

SQL is Structured Query Language, which is a computer language for storing, manipulating and retrieving data stored in a relational database.

QUERY  : -

1.How to create Database  : A Database is defined as a structured set of data. So, in SQL the very first step to store the data in a well structured manner is to create a database. The CREATE DATABASE statement is used to create a new database in SQL.

___ we want create student name database

create database student;  
                                

2. How to check your database create or not / show databases 

show databases;

 

3. How to delete database

drop database student;  

4. How to create a table in Database  : CREATE TABLE creates a new table in the database. It allows you to specify the name of the table and the name of each column in the table.

create table student_info ( sid int(11) primary key not null , sname varchar(100) , sclass int(11) , saddress varchar(100) );  

5. How to check your table create or not in database / show table list 

show tables;  

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6. How to check table desc 

desc student_info;  

7. For drop table in database

drop table student_info;  

8. How to data insert in table : The INSERT INTO statement is used to insert new records in a table.

insert into student_info values (1, 'Aman Kumar' , 5 , 'Mumbai');  

9. check your data insert in table or not

select * from student_info;  

10.  if We want delete row in table  : DELETE statements are used to remove rows from a table.

DELETE FROM student_info WHERE sid=3;  

    

11. How to add column in table

alter table student_info add age int(11);  

12. How to fill blank column

update student_info set age=10;  

13.   find record by id

select* from student_info where sid=2;  

14. find only one value in table

select sname from student_info where sid=1;  

15. Use alias   : AS is a keyword in SQL that allows you to rename a column or table using an alias.

select sname as "STUDENT NAME" ,sclass "CLASS" from student_info;  

16. Select record without duplicate field in table : SELECT DISTINCT specifies that the statement is going to be a query that returns unique values in the specified column(s).

SELECT DISTINCT sname,saddress from student_info;  

17. find two or more value in table : The BETWEEN operator is used to filter the result set within a certain range. The values can be numbers, text or dates.

select * from student_info where sid=1 and sname='Aman Kumar';  

18. Use  OR Syntax :  OR is an operator that filters the result set to only include rows where either condition is true.

select * from student_info where sid=1 OR sid=2;  

19. Search top three rows in table

select * from student_info limit 3;  

20. Search after three id rows 

select * from student_info limit 3 offset 3;  

21. Data show in Descending order : ORDER BY is a clause that indicates you want to sort the result set by a particular column either alphabetically or numerically.

select * from student_info order by sid desc;  

22. show data in last two rows 

select * from student_info order by sid desc limit 2;  

23. How to add total column : SUM() is a function that takes the name of a column as an argument and returns the sum of all the values in that column.

select sum(sid) from student_info;  

24. Find min id from table  : MIN() is a function that takes the name of a column as an argument and returns the smallest value in that column.

select min(sid) from student_info;  

25. Find max id from table  : MAX() is a function that takes the name of a column as an argument and returns the largest value in that column.

select max(sid) from student_info;  

26. How to find the employee whose salary is minimum.

select * from employee where eid=(select min(eid) from employee);  

27. How to find the employee whose salary is highest

select * from employee where eid=(select max(eid) from employee);  

28. How to insert data in blank column : UPDATE statements allow you to edit rows in a table.

update ename from set ename='Rohan Kumar';  

29. Use Inner JOIN : An inner join will combine rows from different tables if the join condition is true.

Table 1. employee Table 2. department SELECT* FROM employee INNER JOIN department ON employee.empid = department.empid;  

30. Use LEFT JOIN  : An outer join will combine rows from different tables even if the join condition is not met. Every row in the left table is returned in the result set, and if the join condition is not met, then NULL values are used to fill in the columns from the right table.

Table 1. employee Table 2. department SELECT* FROM employee LEFT JOIN department ON employee.empid = department.empid;  

31. use RIGHT JOIN

Table 1. employee Table 2. department SELECT* FROM employee RIGHT JOIN department ON employee.empid = department.empid;  

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