What is difference b/w composit key n primary key and
forigion key?
Answer Posted / saraswathi muthuraman
Compost key :
More than one column will be used to create compst key
SQL> create table ts_250 (a number,b number,c number,
primary key(a,c));
Table created.
here column A and column C is used to create compst key.
U can't insert null value in both columns.
Only unique combination of column A and column B value can
be inserted.
Primary key :
Key will be created on a single column in table.
SQL> create table ts_251 (a number,b number,c number,
primary key(a));
Table created.
null value cann't be inserted into column a.
oracle will create a index
only unique value can be inserted into column a.
only one primary key can be created on a table
Is This Answer Correct ? | 5 Yes | 0 No |
Post New Answer View All Answers
what is constraints? Also explain the different types of constraints?
How can I create database in mysql?
what is the procedure to configure the application of mysql?
What is sqlyog?
What is a definer?
What are the common mysql functions?
Does mysql use tcp or udp?
Tell us something about heap tables?
Does mysql case matter?
What is mysql aggregate functions? Explain
How to change a password for an existing user via mysqladmin?
What are date and time data types in mysql?
How do I find my mysql username and password?
How do I start mysql database?
What is the current version of mysql?