2007-02-26 18:17:05 · 5 answers · asked by mukesh1 m 1 in Computers & Internet ➔ Hardware ➔ Laptops & Notebooks
Primary key means it it is the Unique key.Once u defined that key for any value u can not use that value for second time for Example u r Roll Number or Customer id will be unique.
2007-02-26 18:35:25 · answer #1 · answered by z_lokesh 1 · 0⤊ 0⤋
Primary Key is a key applied on a column of a table that can identify every record in the table uniquely. ie. when you query the database on basis of the data in the primary key column, it would return only a single record.
2007-02-27 02:37:31 · answer #2 · answered by Sandy 2 · 0⤊ 0⤋
It is a set of columns used to uniquely identify a row (or a record) in a table. A table may have "only one" primary key. But this key may have one or more columns.
2007-02-27 02:41:00 · answer #3 · answered by deostroll 3 · 0⤊ 0⤋
Primary key mostly used in DBMS. Primary Key is the unique and not null values of an attribute of a table or entity. it is a attribute which defined as uniquely in the table.
Example:Student information is the entity or table .the attribute of this table are : Student name,student Id,Address etc.
student_id is the primary key of this table and this unique or not null in the record of all the student.
2007-02-27 03:31:19 · answer #4 · answered by ravi 1 · 0⤊ 0⤋
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2007-02-27 02:21:58 · answer #5 · answered by abhay kant 2 · 0⤊ 0⤋