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what is the difference between primary key & foreign key?
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Answer / vasavi
primary key does not allow duplicate and null values
primary is unquie.
foreign key allows null values it refers primary key.
foreign key allows duplicate values.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / amuthan
primary key is the parent and foreign is the child.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / anjanareddy
i cleared this question simple.
TAKE A LOOK
primary key:-It doesn't allow NULL values and duplicate values
it is a unique one.
Foreign key:- It allows NULL and duplicate values
It always give reference to primary key of another table
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / zacharia ismail
primary key: primary creates a clustered index on the
column and it doesn't allow null values.
foreign key: A foreign key (FK) is a column or combination
of columns used to establish and enforce a link between the
data in two tables.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / ansul singh
Primary key is unique key but Foreign key always refers to
primary key.
Primary key is the parent & Foreign key is the child.
Primary key is unique, Primary key is not null and
Foreign key is null, Foreign key reference as primary key
is another table.
Primary key will not allow "Null values" & "Duplication
values",
Foreign key will allow "Null values & "Duplicate values" &
it refers to a primary key is another table.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / pravin
The primary key of a relational table uniquely identifies
each record in the table. It can either be a normal
attribute that is guaranteed to be unique (such as Social
Security Number in a table with no more than one record per
person) or it can be generated by the DBMS (such as a
globally unique identifier, or GUID, in Microsoft SQL
Server). Primary keys may consist of a single attribute or
multiple attributes in combination.
Examples:
Imagine we have a STUDENTS table that contains a record for
each student at a university. The student's unique student
ID number would be a good choice for a primary key in the
STUDENTS table. The student's first and last name would not
be a good choice, as there is always the chance that more
than one student might have the same name.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / suraj menon
primary key is used to identify a row and it doesnot allow
null values. It avoids duplication of rows.
Foreign key will allow "Null values" and "Duplicte values"
and it refers to a primary key in anoter table.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / raffi.shaik
Primary key is unique
primary key is not NULL and
foreign key is NULL
foreign key reference as Primary key in another table
Primary key is unique key but foreign key always refers to
primary key
primary key is used to identify a row and it does not allow
null values. It avoids duplication of rows.
whereas foreign key refers to a column or combination of
columns included in the definition of referential integrity.
In the context of relational databases, a foreign key is a
referential constraint between two tables.[1] The foreign
key identifies a column or a set of columns in one
(referencing) table that refers to a column or set of
columns in another (referenced) table. The columns in the
referencing table must form a primary key or unique key.
| Is This Answer Correct ? | 1 Yes | 0 No |
Answer / baburao
primary key is a key which can define unique values
where as foreign key refers to a parent table and depends
on primary key
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / g. rajamani
Primary key is a key, that is a not null or unique key. But
foriegn key is null, that is refere to the primary key.
| Is This Answer Correct ? | 0 Yes | 0 No |
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