Sawaal
  • Home/
  • Searching for L

 Searching for "L"

Q:

My SQL statement SELECT AVG(SALARY) FROM EMP yields inaccurate results. Why?

Answer

Because SALARY is not declared to have NULLs and the employees for whom the salary is not known are also counted.


 

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

File contains 5 records say D,E,F,C,A-I want to copy D and A records only by using file-aid?

Answer

Go to file-aid copy option.Enter the from dataset to be copied and to dataset to which you want to copy.go to options. Enter 0 at Initial records to skip field.Then enter 3 at the no of records to skip field and 1 to no of records to select.press enter and PF3.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

What is the self-referencing constraint?

Answer

A31. The self-referencing constraint limits in a single table the changes to a primary key that the related foreign key defines. The foreign key in a self referencing table must specify the DELETE CASCADE rule.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

What do you accomplish by GROUP BY ... HAVING clause?

Answer

GROUP BY partitions the selected rows on the distinct values of the column on which you group by. HAVING selects GROUPs which match the criteria specified

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

Why is free space left in KSDS Dataset?

Answer

While allocating KSDS Datasets, free space is declared at regular intervals at the time of initial loading. This is done because this free space is utilized for keeping the data arranged in sequence physically, even though inserted randomly.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

How can record locking be achieved in those DB2 versions which do not support it?

Answer

It can be done by setting the record length’s size to more than half of the page’s size.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

Name and explain the type of locks?

Answer

There are three types of lock, namely:


Shared – This type of lock permits two or more programs to read from the locked space but does not allow them to change it.


Update – This lock is more lenient. It permits the program to read and change the locked space.


Exclusive – This lock restricts all users from accessing the locked space.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview

Q:

What does a deadlock mean in DB2?

Answer

When two independent processes contend for the same resource or the resources reserved by one another, it is called a deadlock. -911 and -913 are the SQLcode for a deadlock.

Report Error

View answer Workspace Report Error Discuss

Subject: Mainframe Interview