Most Important SQL Query for Interview:-
1) Write Query to add and remove a new column in tables?
2) Write a Query to add a primary Key into a table?
3) Write a Query to add a foreign key in a table?
4) Write a Query to rename the table, database, and column?
5) Write q Query to implement self join, inner join, outer join, and natural join?
6) Write a Query to use Group by and having
Most Important SQL Query for Interview:-
Dept(Deptid, Deptname)
Emp(Empid,Empname, Job, Salary, Deptid)
7) WAQ to display total employee and each dept?
8) WAQ to display the record of the employee who is getting second max salary?
9) WAQ to select deptname and job where number of employee is more then 3?
10) WAQ to display max, min,avg salary on each dept excluding IT dept?
11) WAQ to display the name of dept where employee is null?
12) WAQ to display the empname whose salary is minium?
Answers of all Query :->
ردحذف01: Alter Table babubhaiya Add newadd INT NOT NULL AFTER state;
ALTER TABLE babubhaiya DROP newadd;
02: ALTER table syam add PRIMARY KEY( id);
03: ALTER TABLE herapheri add FOREIGN KEY (id) REFERENCES babubhaiya (id);
04: ALTER TABLE herapheri RENAME TO lakshmi; -> table name change
ALTER TABLE syam CHANGE id cid INT(11) NOT NULL AUTO_INCREMENT;
05: SELECT a.cid,a.course,a.Branch FROM syam a INNER join syam b on a.Branch = b.Branch->self join
SELECT * FROM syam a INNER join babubhaiya b on a.cid = b.id -> inner join
SELECT * FROM syam a LEFT OUTER join babubhaiya b on a.cid = b.id -> left OUTER join
SELECT * FROM syam a RIGHT OUTER join babubhaiya b on a.id = b.id -> right OUTER join
SELECT * FROM syam NATURAL join babubhaiya -> natural join
06: SELECT syam.id,syam.course,syam.Branch,COUNT(*) FROM syam GROUP BY Branch ->group by
SELECT syam.id,syam.course,syam.Branch,COUNT(*) FROM syam GROUP BY Branch HAVING count(Branch) >3 ->having
07: SELECT emp.empname,dept.deptname from emp NATURAL join dept
08: select * from emp group by salary order by salary desc limit 1,1
09: SELECT dept.deptname,emp.job from emp INNER join dept on emp.deptid=dept.deptid GROUP by dept.deptname HAVING COUNT(*)>3
10: SELECT max(salary) from emp WHERE dept=it
SELECT min(salary) from emp WHERE dept=it
SELECT avg(salary) from emp WHERE dept=it
11: SELECT * from dept WHERE dept.deptid NOT IN ( SELECT emp.deptid from emp)// run query outside table
12: SELECT emp.empname from emp WHERE salary = (SELECT min(salary) from emp)