What Is The Difference Between Unique Key And Primary Key?

1.	What Is The Difference Between Unique Key And Primary Key?
Answer» Unique key is one or more COLUMNS that can be used to UNIQUELY IDENTIFY a ROW in a table. A table can have one or more unique keys. Unique keys can contain null values. While on the other hand table can have only one primary key. One or more columns in a primary key cannot contain null values. Unique key is one or more columns that can be used to uniquely identify a row in a table. A table can have one or more unique keys. Unique keys can contain null values. While on the other hand table can have only one primary key. One or more columns in a primary key cannot contain null values.

Answer»

Unique key is one or more COLUMNS that can be used to UNIQUELY IDENTIFY a ROW in a table. A table can have one or more unique keys. Unique keys can contain null values. While on the other hand table can have only one primary key. One or more columns in a primary key cannot contain null values.

Unique key is one or more columns that can be used to uniquely identify a row in a table. A table can have one or more unique keys. Unique keys can contain null values. While on the other hand table can have only one primary key. One or more columns in a primary key cannot contain null values.

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