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rajmanisha
rajmanisha • Jul 10, 2017

what is primary key?

what is primary key?
Kaustubh Katdare
Kaustubh Katdare • Jul 10, 2017
rajmanisha
what is primary key?
How about adding a little more reference to your question? Are we talking about databases here?
rajmanisha
what is primary key?
LMGTFY
Shweta Chauhan
Shweta Chauhan • Jul 11, 2017
In context of DBMS, primary key is a column in a table that uniquely identifies the rows of that table.Several rows of a table can have similar value for a column but in case if that column is a primary key for that table, it can't be same.
In addition to uniquely identifying a row, it also ensures that there cannot be any null value in that column(if it is the primary key for that table)
A simple example:
upload_2017-7-11_16-13-27
Here Roll No. column is the primary key of this table so values in that column cannot be same,but name and marks can have similar values.
rajmanisha
what is primary key?
your aadhar number (Social security number ) in the US, Driving license number etc all can be your your primary key.

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