What is Primary Key?




Answers were Sorted based on User's Feedback



What is Primary Key?..

Answer / ashis kumar jena

A primary key is one which uniquely identifies a row
of a table.
This key does not allow null values and also
does not allow duplicate values.
Each table should have a primary key, and each table can
have only one primary key.

Is This Answer Correct ?    16 Yes 2 No

What is Primary Key?..

Answer / perumal

1. Primary Key Doesn't allow the NULL values and also
does not allow duplicate values.

2. Primary Key has the Unique Columns.

3. Primary Key Uniquely Identify the each row of the tables.

Is This Answer Correct ?    14 Yes 3 No

What is Primary Key?..

Answer / hannan oca

primary key =notnull+unique value in column

a table consist of only one primary key.

Example

a primary key is like a father in house, like only one but
there may be a lot of childs just like columns.

Is This Answer Correct ?    3 Yes 1 No




What is Primary Key?..

Answer / satheeh

Primary key is nothing but restriction or condition or constraint given to a specific column to avoid the null and duplicate values.
primary key=not null+unique
that means primary key performs both operations at a time.
primary key plays vital role when relationship between two or more tables

Is This Answer Correct ?    2 Yes 1 No

Post New Answer



More SQL PLSQL Interview Questions

how to delete duplicate rows from a specified table(only single table) how do you know which join is need to be used

11 Answers   UST,


What are triggers and its uses?

0 Answers  


what is the need of the cursor attribute notfound..(because using found attribute we can complete the task......found + negation operator = not found )

2 Answers   Tech Mahindra,


what are date and time functions in mysql? : Sql dba

0 Answers  


What is normalization? dec 2009

3 Answers   Cognizant,






what is a cursor

9 Answers   TCS, IBM, Wipro,


How to order siblings in oracle hierarchy queries?

0 Answers  


i have xml source. xml source having lacks of records. i want extract/retrive xml source data using sql query. please tell me how to write query.

4 Answers   TCS,


what are the advantages of package?

7 Answers   iFlex,


What is a table?

0 Answers  


What is referential integrity ?

3 Answers   BirlaSoft,


How do you use collections in procedure to return the resultset?

0 Answers  






Categories