ONLINE COMPUTER EDUCATION

Analytical functions: It is known as window function. It performs calculations on the set of table rows which are related to the current row. Not like an aggregate function, it will return the single result for the group of rows. It will return a value for each row in the result set. It will return the aggregate results and don't group the result set. It will return the group value multiple times with each record. Group of rows is also called as window which is defined through the help of analytical clause. select * from emp; select deptno,count(*) EmployeeCount from emp group by deptno order by 1; We can find out the number of employees count in the each department. select empno,ename,deptno,count(*) over (partition by deptno order by empno) as employee_count from emp; It will count the number of employees in each department. Within each partition, results are sorted as per empno which is specified in the over clause. select empno,ename,deptno,count(*)employee_count from emp group...

 Definition: It is nothing but the conditions or the restrictions are assigned to each and every column of the database in order to maintain the data integrity. It is used to specify the rules for the data in a table. It is used to limit the type of the data that will go into the table. It ensures the accuracy and reliability of the data in the table. It can be applied at the column level or the table level. Column level constraints are applied at the column level. Table level constraints are applied at the whole table. It will not allow us to enter the information for the entire result. How to create constraint in SQL? It can be created when the table is created with the help of create table statement. It can also be created after the table is created with the help of alter statement. Syntax: Create table table_name( column1 datatype constraint, column2 datatype constraint, column3 datatype constraint, ... ... ... column n datatype constraint); Types of constraint: 1) NOT NULL: I...