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If you're asking if a table can have multiple columns as a primary key, then for MS SQL Server, the answer is yes, and it's called a composite (corrected) key.
The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).
22 Ιουλ 2024 · If a primary key constraint is defined on more than one column, values can be duplicated within one column, but each combination of values from all the columns in the primary key constraint definition must be unique.
A primary key is a column or a group of columns that uniquely identifies each row in a table. You create a primary key for a table by using the PRIMARY KEY constraint. If the primary key consists of only one column, you can define use PRIMARY KEY constraint as a column constraint: pk_column data_type PRIMARY KEY, ...
It is also possible to designate more than one column (i.e. two or more columns) as the PRIMARY KEY. Such a PRIMARY KEY is also referred to as a COMPOSITE KEY. It might be required to define a COMPOSITE KEY if none of the columns in a table satisfies the non-null and unique constraint conditions.
18 Αυγ 2019 · A composite primary key is a primary key consisting of multiple columns. Microsoft usually refers to these as multicolumn primary keys in its documentation. This article provides an example of creating a composite primary key using Transact-SQL in SQL Server.
18 Απρ 2024 · A primary key column is identified by a primary key symbol in its row selector. If a primary key consists of more than one column, duplicate values are allowed in one column, but each combination of values from all the columns in the primary key must be unique.
