CommandBehavior Enum

Definition

Namespace:

System.Data

Assembly:

System.Data.Common.dll

Provides a description of the results of the query and its effect on the database.

This enumeration supports a bitwise combination of its member values.

public enum class CommandBehavior

[System.Flags]
public enum CommandBehavior

[<System.Flags>]
type CommandBehavior = 

Public Enum CommandBehavior

Inheritance

Object

ValueType

Enum

CommandBehavior

Attributes

FlagsAttribute

Fields

CloseConnection	32	When the command is executed, the associated Connection object is closed when the associated DataReader object is closed.
Default	0	The query may return multiple result sets. Execution of the query may affect the database state. Default sets no CommandBehavior flags, so calling ExecuteReader(CommandBehavior.Default) is functionally equivalent to calling ExecuteReader().
KeyInfo	4	The query returns column and primary key information. The provider appends extra columns to the result set for existing primary key and timestamp columns.
SchemaOnly	2	The query returns column information only. When using SchemaOnly, the .NET Framework Data Provider for SQL Server precedes the statement being executed with SET FMTONLY ON.
SequentialAccess	16	Provides a way for the DataReader to handle rows that contain columns with large binary values. Rather than loading the entire row, SequentialAccess enables the DataReader to load data as a stream. You can then use the GetBytes or GetChars method to specify a byte location to start the read operation, and a limited buffer size for the data being returned.
SingleResult	1	The query returns a single result set.
SingleRow	8	The query is expected to return a single row of the first result set. Execution of the query may affect the database state. Some .NET data providers may, but are not required to, use this information to optimize the performance of the command. When you specify SingleRow with the ExecuteReader() method of the OleDbCommand object, the .NET Framework Data Provider for OLE DB performs binding using the OLE DB IRow interface if it is available. Otherwise, it uses the IRowset interface. If your SQL statement is expected to return only a single row, specifying SingleRow can also improve application performance. It is possible to specify SingleRow when executing queries that are expected to return multiple result sets. In that case, where both a multi-result set SQL query and single row are specified, the result returned will contain only the first row of the first result set. The other result sets of the query will not be returned.

Remarks

The CommandBehavior values are used by the ExecuteReader method of IDbCommand and any implementing classes.

A bitwise combination of these values may be used.

CommandBehavior is ignored when used to define a SqlNotificationRequest or SqlDependency and should therefore not be used. Use the constructor that does not require a CommandBehavior parameter in these two cases.

Notes on individual enumeration members

When using KeyInfo, the .NET Framework Data Provider for SQL Server precedes the statement being executed with SET FMTONLY OFF and SET NO_BROWSETABLE ON. The user should be aware of potential side effects, such as interference with the use of SET FMTONLY ON statements. For more information, see SET FMTONLY (Transact-SQL).

Note

Use SequentialAccess to retrieve large values and binary data. Otherwise, an OutOfMemoryException might occur and the connection will be closed.

When you specify SequentialAccess, you are required to read from the columns in the order they are returned, although you are not required to read each column. Once you have read past a location in the returned stream of data, data at or before that location can no longer be read from the DataReader. When using the OleDbDataReader, you can reread the current column value until reading past it. When using the SqlDataReader, you can read a column value only once.