Interview Questions

Oracle constraints are used to maintain consistent of data and ensure the data is properly maintained. A constraint is more or less a restriction we try to apply on a table.
Types of constraints:
- Check constraints
- NOT NULL constraint
- PRIMARY KEY constraint
- REFERENCES constraint
- UNIQUE constraint

1. A fixed budget is established for a specific level of activity whereas flexible budget is prepared for various levels of activity.

2. Fixed budget cannot be changed after the period commences, whereas a flexible budget can be changed after the period commence.

3. Fixed budget is more suitable for fixed expenses whereas flexible budget takes both fixed as well as variable expenses in account.

4. Fixed budget includes only fixed costs, whereas a flexible budget includes fixed costs, variable costs and semi variable costs.

5. Fixed budget is mainly used in planning stage whereas flexible budget is used in controlling stage.

The following commands are available for the Program Control services:

LINK: To pass control to another program at the lower level, expecting to be returned. XCTL: To pass control to another program at the same level, not expecting to be returned.

RETURN:  To return to the next higher-level program or CICS. 

LOAD: To load a program. 

RELEASE: To release a program.

Aggregate functions perform a calculation on a set of values and return a single value. Aggregate functions ignore NULL values except COUNT function. HAVING clause is used, along with GROUP BY, for filtering query using aggregate values.

Following functions are aggregate functions. 

AVG, MIN CHECKSUM_AGG, SUM, COUNT, STDEV, COUNT_BIG, STDEVP, GROUPING, VAR, MAX. VARP

DB2 precompiler (if embedded sql used), CICS translator (if CICS program), COBOL compiler, Link editor. If DB2 program, create plan by binding the DBRMs.

PL/SQL exceptions are raised using the RAISE command. This command is used when exceptions are defined by programmer and not implicit exceptions.

Example:

Declare and raising an exception:

DECLARE

short_of_attendance EXCEPTION;

min_attendance NUMBER(4);

BEGIN

...

IF min_attendance < 10 THEN

RAISE short_of_attendance;

END IF;

EXCEPTION

WHEN short_of_attendance THEN

-- handle the error

END;