What is the difference between primary key & unique index ?
Answer Posted / uddipto banerji
1. Primary Key is a column or a set of columns that uniquely identifies a row.Its purpose RECORD UNIQUENESS
2. Primary Key will not allow duplicate values.
3. Primary Key will not allow null.
4. Primary Key is not compulsory but recommended.
5. Primary Key helps to identify one record from another.
6. Only One Primary Key is allowed per table.
7. Unique Indexes is created automatically if there is Primary Key.
8. One table can combine upto 16 columns in a Composite Primary Key.
9. A table can have more than one Unique Key which is not possible in a Primary Key.
Is This Answer Correct ? | 10 Yes | 2 No |
Post New Answer View All Answers
What is copy pending and check pending in db2?
i tried to copy some records from microsoft excel to as-400 physical file through "Bosanova" emulation. Out of 14000 records only 12000 records copies and subsequently programe started to hang. Then, i closed the program forcefully. I did' under stand the problem. Also when i try to compile the physical file it is showing as "The file in use". How to overcome this problem?
Explain dclgen.
How to run db2 command in windows?
What is rct?
What parameters are used to control the free space in DB2?
How to restart a DB2 program?
What does db2 blu stand for?
How do you stop a db2 database in linux?
Define check constraint.
What is the difference between db2 and oracle?
What is deadlock in db2?
What is scrollable cursor in db2?
What is a db2 schema?
Define sqlca.