Name

PrimaryKey

Synopsis

DataColumn[] pka = DataTable.PrimaryKey;

DataTable.PrimaryKey = pka;

Accesses the array of DataColumn objects that make up the primary key of the table.

Example

The primary key for a table can be set by specifying an array of DataColumn objects from the table. The following example shows how to create a primary key based on two columns:

// set the primary key based on two columns in the DataTable

DataTable dt = new DataTable("MyTable");

dt.Columns.Add("PK_Field1", typeof(System.Int32));

dt.Columns.Add("PK_Field2", typeof(System.Int32));

// add other table columns

dt.PrimaryKey = new DataColumn[] {dt.Columns["PK_Field1"],

    dt.Columns["PK_Field2"]};

To remove the primary key, simply set the primary key to null, as shown in the following example:

// remove the primary key

dt.PrimaryKey = null;

Note

The PrimaryKey property accesses the DataColumn object or objects that make up the primary key of DataTable. The primary key acts as a unique constraint for the table and also allows records to be located using the Find( ) method of the DataTable rows collection.