Answer / bishwajit

Primary key is unique key but foriegn key always refers to
primary key
primary key is not NULL and
foreign key is NULL

Answer / neel

Primary key is unique key that uniquely identifies each data
in a table (t1) whereas foreign key is the key that acts as
Primary key for some other table (t2) and is a part of the
table that contains Primary key (t1).

Answer / surya

a primary key is used to indicate uniqueness of all the rows
in the table
where as the foreign key is used to refer other table from
the current table

Answer / nageswararao.k

primary key:- A primary contains unique and notnull.it means
a primary key column does not contain nullvalues and
duplicates.A table containe only one primary key.using this
we can access the data from table easily.
foreign key:-a fk can contain duplicate values but it not
contain null values.using fk to establish relationship
between two tables. a parent table primary key should be
referenced by child table primary key.
one fk should be referenced by only one primary key


the main difference between two keys is
pk is used to access the data from table.
fk is used to establish the relationship between two tables.
pk does not allowed duplicate and null values.
fk can allows duplicate values and does not allowed null
values

Answer / karthik

primary key:a primary key is combination of unique,and not
null constraint and a table can have only one primary key

foreign key ;
a foreign key is a reference of the primary key and returns
reference from itself or from other table data

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