What is a primary key, and how is it different from a unique key?
Answers were Sorted based on User's Feedback
Answer / nashiinformaticssolutions
• Primary Key:
o Ensures each row in a table is unique.
o Cannot contain NULL values.
o A table can have only one primary key.
• Unique Key:
o Ensures all values in a column are unique.
o Can contain a single NULL value.
o A table can have multiple unique keys.
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / glibwaresoftsolutions
• Primary Key:
o Ensures each row in a table is unique.
o Cannot contain NULL values.
o A table can have only one primary key.
• Unique Key:
o Ensures all values in a column are unique.
o Can contain a single NULL value.
o A table can have multiple unique keys.
| Is This Answer Correct ? | 0 Yes | 0 No |
• Primary Key:
o Ensures each row in a table is unique.
o Cannot contain NULL values.
o A table can have only one primary key.
• Unique Key:
o Ensures all values in a column are unique.
o Can contain a single NULL value.
o A table can have multiple unique keys.
| Is This Answer Correct ? | 0 Yes | 0 No |
What are the limitations of sql express?
How does one use sql*loader to load images, sound clips and documents? : aql loader
Why we use join in sql?
Can a key be both primary and foreign?
What is auto increment?
Is sql low level language?
7. Where would you look for errors from the database design?
Is left join faster than inner join?
What is nvl function?
What is pragma in pl sql?
what will be the output: select 1 from emp union all select 2 from emp;
Is pl sql better than sql?
Oracle (3259)
SQL Server (4518)
MS Access (429)
MySQL (1402)
Postgre (483)
Sybase (267)
DB Architecture (141)
DB Administration (291)
DB Development (113)
SQL PLSQL (3330)
MongoDB (502)
IBM Informix (50)
Neo4j (82)
InfluxDB (0)
Apache CouchDB (44)
Firebird (5)
Database Management (1411)
Databases AllOther (288)