Interested to Buy Any Domain ? << Click Here >> for more details...
what is primary key,unique key, foreign key? can u teach me
in simple language?
- 44 Answers
- 189039 Views
- Banking, CMC, CTS, HCL, Infosys, Keggfarms, SkyEss, Sunrise, TCS, Web Synergies, Wipro, I also Faced
- E-Mail Answers
Answer Posted / anbarasu
UNIQUE KEY: A Table may contain one or more UNIQUE
constraints. It’s allowing only one null value. Use this
key we maintain unique vales in the table.
FOREIGN KEY: A key used in one table to represent the value
of a primary key in a related table. While primary keys
must contain unique values, foreign keys may have
duplicates. For instance, if we use student ID as the
primary key in a Students table (each student has a unique
ID), we could use student ID as a foreign key in a Courses
table: as each student may do more than one course, the
student ID field in the Courses table (often shortened to
Courses. student ID) Will hold duplicate values.
| Is This Answer Correct ? | 0 Yes | 0 No |
Post New Answer View All Answers
What is a trace file?
Define stored procedure?
Explain data independence & its types.
What are the tools used for backup and ticketing?
What is a database connection string?
During insert operation in Netezza Connector, if we give direct option as Yes , is there any issue?
How do you pass parameter in stored procedure?
What is the purpose of firebase?
What is the best database software for small businesses?
What are the most common databases?
How much does it cost to build a database?
Explain entity type?
What advantages does DBMS have over traditional file systems?
Is database a hardware or software?
How does non-cluster index functions?
