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Parameter Object

  • บทความ

Represents a parameter or argument associated with a Command object based on a parameterized query or stored procedure.

Remarks

Many providers support parameterized commands. These are commands in which the desired action is defined once, but variables (or parameters) are used to alter some details of the command. For example, a SQL SELECT statement could use a parameter to define the matching criteria of a WHERE clause, and another to define the column name for a SORT BY clause.

Parameter objects represent parameters associated with parameterized queries, or the in/out arguments and the return values of stored procedures. Depending on the functionality of the provider, some collections, methods, or properties of a Parameter object may not be available.

With the collections, methods, and properties of a Parameter object, you can do the following:

  • Set or return the name of a parameter with the Name property.

  • Set or return the value of a parameter with the Value property. Value is the default property of the Parameter object.

  • Set or return parameter characteristics with the Attributes, Direction, Precision, NumericScale, Size, and Type properties.

  • Pass long binary or character data to a parameter with the AppendChunk method.

  • Access provider-specific attributes by using the Properties collection.

If you know the names and properties of the parameters associated with the stored procedure or parameterized query you want to call, you can use the CreateParameter method to create Parameter objects with the appropriate property settings and use the Append method to add them to the Parameters collection. This lets you set and return parameter values without having to call the Refresh method on the Parameters collection to retrieve the parameter information from the provider, a potentially resource-intensive operation.

The Parameter object is not safe for scripting.

This section contains the following topic.

See Also

Command Object (ADO)
CreateParameter Method (ADO)
Parameters Collection (ADO)
Properties Collection (ADO)