what is primary key?

Replies

• 

  Kaustubh Katdare

  rajmanisha

  what is primary key?

  How about adding a little more reference to your question? Are we talking about databases here?
• 

  Neeraj Sharma

  rajmanisha

  what is primary key?

  #-Link-Snipped-#
• 

  Shweta Chauhan

  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:
  
  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.
• 

  vinod12345madhu

  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.