DB2 Interview Questions – Set 05

What is the physical storage length of TIME data type?

The physical storage length of TIME data type is 3 bytes.

Which component is used to execute the SQL statements?

Database Services component is used to execute the SQL statement. It also manages buffer pool.

On which levels locks can be applied?

Locking can be applied on either of Page, table and table space.

What is the reason behind not using SELECT * in Embedded SQL programs?

There are three reasons for not using SELECT * in embedded SQL programs:

  • If you change the table structure i.e. adding a field, the program will have to be modified.
  • Program can retrieve the columns which it might not use, leading an I/O overhead.
  • The chance of an index only scan is lost.

How can you count the number of rows from a table TAB?

By applying the following query:

SELECT COUNT(*) FROM TAB