The DataColumn is the fundamental building block for creating the schema of a DataTable. You build the schema by adding one or more DataColumn objects to theDataColumnCollection. For more information, see 向数据表中添加列.

Each DataColumn has a DataType property that determines the kind of data the DataColumn contains. For example, you can restrict the data type to integers, or strings, or decimals. Because data that is contained by the DataTable is typically merged back into its original data source, you must match the data types to those in the data source. For more information, see ADO.NET 中的数据类型映射.

Properties such as AllowDBNull, Unique, and ReadOnly put restrictions on the entry and updating of data, thereby helping to guarantee data integrity. You can also use theAutoIncrement, AutoIncrementSeed, and AutoIncrementStep properties to control automatic data generation. For more information about AutoIncrement columns, see 创建 AutoIncrement 列. For more information, see 定义主键.

You can also make sure that values in a DataColumn are unique by creating a UniqueConstraint and adding it to the ConstraintCollection of the DataTable to which theDataColumn belongs. For more information, see 数据表约束.

To create a relation between DataColumn objects, create a DataRelation object and add it to the DataRelationCollection of a DataSet.

You can use the Expression property of the DataColumn object to calculate the values in a column, or create an aggregate column. For more information, see 创建表达式列.

The following example creates a DataTable with several DataColumn objects.

private void MakeTable()
{ 
    // Create a DataTable. 
    DataTable table = new DataTable("Product");

    // Create a DataColumn and set various properties. 
    DataColumn column = new DataColumn(); 
    column.DataType = System.Type.GetType("System.Decimal"); 
    column.AllowDBNull = false; 
    column.Caption = "Price"; 
    column.ColumnName = "Price"; 
    column.DefaultValue = 25; 

    // Add the column to the table. 
    table.Columns.Add(column); 

    // Add 10 rows and set values. 
    DataRow row; 
    for(int i = 0; i < 10; i++)
    { 
        row = table.NewRow(); 
        row["Price"] = i + 1; 

        // Be sure to add the new row to the 
        // DataRowCollection. 
        table.Rows.Add(row); 
    } 
}

.NET Framework

.NET Framework Client Profile

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008（不支持服务器核心角色）, Windows Server 2008 R2（支持带 SP1 或更高版本的服务器核心角色；不支持 Itanium）

This type is safe for multithreaded read operations. You must synchronize any write operations.

参考

其他资源