What is the difference between Sub-Query & Co-Related Sub-Query?
Answers:
When queries are written in a nested manner then it is termed as a sub-query. A Sub-Query get executed once for the parent statement whereas Co-Related Sub-Query get executed once for each row of the parent query.
Select Empname, Deptno, Salary from Employee Emp where Salary = (Select Max(Salary) from Employee where Deptno = Emp.Deptno) order by Deptno
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