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CBSE Class 12 Informatics Practices Question 43 of 79

MySQL SQL Revision Tour — Question 11

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Question 11

What is primary key ? What is PRIMARY KEY constraint ?

Answer

A primary key is a unique identifier for each record in a table, and it must be unique and not null. A PRIMARY KEY constraint declares a column or one group of columns as the primary key of the table. This constraint must be applied to columns declared as NOT NULL.