The GetSchemaTable method returns a DataTable property that contains the column schema for a DataReader. The DataTable contains one row for each field in the resultset. Each column maps to a property of the field in the resultset. The ColumnName property of the DataTable column is the name of the field's property, such as the ColumnName, DataType, ColumnSize, IsKeyColumn, or IsAutoIncrement property. The value of the DataTable column is the value of the field's property, such as the FirstName value for the ColumnName property.