Bureaucrats, forumadmin, Administrators
257
edits
Changes
Difference Between Primary Key And Unique (edit)
Revision as of 16:41, 3 March 2015
, 16:41, 3 March 2015Created page with "<tab sep=bar head=top class=diff> '''Primary Key''' | '''Unique''' A primary key is a constraint that ensures that a fi..."
<tab sep=bar head=top class=diff>
'''Primary Key''' | '''Unique'''
A primary key is a constraint that ensures that a field or column of a sql table does not hold duplicate or null values | Unique is a constraint that a field does not have duplicates but allows null values.
There can be only one primary key in a sql table | A Unique constraint can be applied on more than one field.
</tab>
'''Primary Key''' | '''Unique'''
A primary key is a constraint that ensures that a field or column of a sql table does not hold duplicate or null values | Unique is a constraint that a field does not have duplicates but allows null values.
There can be only one primary key in a sql table | A Unique constraint can be applied on more than one field.
</tab>