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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).
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.
4 Οκτ 2021 · A primary key is a constraint put on a column or columns in a table to guarantee each row in a table is unique. One aspect that makes a table relational is that it has unique rows. If there are two rows in a table with exactly the same data, that table is not considered relational.
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, ...
18 Απρ 2024 · In Table Designer, select the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you select the row selectors for the other columns. Right-click the row selector for the column and select Set Primary Key.
18 Αυγ 2019 · You can create a composite primary key just as you would create a single primary key, except that instead of specifying just one column, you provide the name of two or more columns, separated by a comma.
