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what is the difference between primary key & foreign key?
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Answer / vij&pani
Primary key is unique key but foriegn key always refers to
primary key
| Is This Answer Correct ? | 327 Yes | 50 No |
Answer / ramprakash
Primary keys enforce entity integrity by uniquely
identifying entity instances. Foreign keys enforce
referential integrity by completing an association between
two entities.
| Is This Answer Correct ? | 275 Yes | 50 No |
Answer / guest
Primary key is unique
primary key is not NULL and
foreign key is NULL
foreign key reference as Primary key in another table
| Is This Answer Correct ? | 250 Yes | 62 No |
Answer / guest
primary key is used to identify a row and it doesnot allow
null values. It avoids duplication of rows.
whereas foreign key refers to a column or combination of
columns included in the defenition of referential integrity.
| Is This Answer Correct ? | 155 Yes | 19 No |
Answer / muneer
Primary Key is unique Key entire the table and which is
also NOT NULL
where as foriegn key is the null & which references the
primary key .
| Is This Answer Correct ? | 147 Yes | 28 No |
Answer / shaik gouse peer
Basic difference betweeen Primary key and foreign key is :
Primary key will not allow "Null values" and "Duplicate
values"
Foreign key will allow "Null values" and "Duplicte values"
and it refers to a primary key in anoter table.
| Is This Answer Correct ? | 130 Yes | 25 No |
Answer / guest
primary key is the parent and foreign is the child.
| Is This Answer Correct ? | 132 Yes | 73 No |
Answer / hardik patel
primary key is used to identify a row and it doesnot allow
null values. It avoids duplication of rows.
whereas foreign key refers to a column or combination of
columns included in the defenition of referential integrity.
| Is This Answer Correct ? | 65 Yes | 20 No |
Answer / gaurav , ashish ,preeti , main
Primary key is used to identify a row in a table and it
doesnot allow null values. It avoids duplication of rows.
whereas foreign key refers to a column or combination of
columns included in the defenition of referential integrity
| Is This Answer Correct ? | 57 Yes | 16 No |
Answer / raghu
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 ? | 58 Yes | 20 No |
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