what is primary key,unique key, foreign key? can u teach me
in simple language?
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 database example?
Does facebook use graph database?
What is ole db in ssis?
Is data lake a database?
What is odm database?
What is the difference between primary and candidate key?
query to Compare data of two tables between two different Databases(Oracle and SQL Server) Eg., Source Database: Oracle Table: Employee Target Database : SQL Server Table : emp
What is relational database with example?
what are wrappers and build ups and what it's use?
After normalization, what are the conditions which have to keep in mind to de-normalize it?
What is the difference between specialization and generalization?
What is the Difference Primary key and Unique Key
How does non-cluster index functions?
What is the database url?
can i use the commands "modify" and Change in DB2 to alter my column datatype and its name in a table?