Question

define primary key why do we need primary key​

Answer 1

Answer:

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Answer 2

Answer:

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records. A primary key's main features are: Itmust contain a unique value for each row of data. It cannot contain null values.

Explanation:

need

A primary key is used to ensure data in the specific column is unique. You can only set constraints withprimary keys, by setting a foreign key to another column which creates a relationship with the column that has the primary key set. ... The id column is likely to be a primary key because is needs to be unique.