Difference between primary key and unique key ?
Answer Posted / austin johnson
we can't insert a NULL value into to coloumn holding
primary key constrain.
where as we can insert a NULL value to a unique key feild.
Remember, both keys are used to identify the
rows/tuple/entry of the table uniquely.
so, only once u can enter a NULL value into the unique key
feild.
Is This Answer Correct ? | 146 Yes | 57 No |
Post New Answer View All Answers
How to connect to oracle using service name instead of sid?
Name the three major set of files on disk that compose a database in Oracle?
What are the different types of synonyms?
What is the string concatenation operator in oracle?
State and explain the different types of data models?
Explain mutating triggers.
what is difference between sql plus and sql*plus? (not sql and sql plus).
Can you have more than one content canvas view attached with a window ?
Explain a segment?
Can we connect to ORACLE db using Windows Authentication?
How to unlock the sample user account in oracle?
How to view existing locks on the database?
What is the quickest way to export a table to a flat file?
What is an oracle and why it is used?
How to view all columns in an existing table?