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18 Απρ 2024 · You can define a primary key in the SQL Server Database Engine by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index.
24 Φεβ 2013 · A primary key is a unique index that is clustered by default. By default means that when you create a primary key, if the table is not clustered yet, the primary key will be created as a clustered unique index. Unless you explicitly specify the nonclustered option.
11 Νοε 2011 · So now that we know what a good clustered index key is, does the primary key (which is a data modelling logical property) match the requirements? If yes, then the PK should be clustered. If no, then the PK should be non-clustered.
16 Σεπ 2024 · If you configure a PRIMARY KEY, Database Engine automatically creates a clustered index, unless a clustered index already exists. When you try to enforce a PRIMARY KEY constraint on an existing table and a clustered index already exists on that table, SQL Server enforces the primary key using a nonclustered index.
22 Ιουλ 2024 · If clustered or nonclustered isn't specified for a primary key constraint, clustered is used if there's no clustered index on the table. All columns defined within a primary key constraint must be defined as not null.
21 Ιαν 2013 · A Primary Key is a column or set of columns that uniquely identifies each row in a table. It should be NOT NULL, meaning it cannot contain null values. A good candidate for a clustered index key is a column that also uniquely identifies each row and is NOT NULL.
When creating a table with a primary key, SQL Server automatically creates a clustered index based on the primary key columns. A table has only one clustered index. Use the CREATE CLUSTERED INDEX statement to create a new clustered index for a table.
