[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] | Reference for unit 'DB' (#fcl)

# TParam

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Parameter description class

## Declaration

Source position: db.pas line 1178

`type TParam = class(TCollectionItem)`
`public`
`constructor Create();` |  | Create a new parameter value
`procedure Assign(); override;` |  | Assign one parameter instance to another
`procedure AssignField();` |  | Copy value from field instance
`procedure AssignToField();` |  | Assign parameter value to field
`procedure AssignFieldValue();` |  | Assign field value to the parameter.
`procedure AssignFromField();` |  | Copy field type and value
`procedure Clear;` |  | Clear the parameter value
`procedure GetData();` |  | Get the parameter value from a memory buffer
`function GetDataSize;` |  | Return the size of the data.
`procedure LoadFromFile();` |  | Load a parameter value from file
`procedure LoadFromStream();` |  | Load a parameter value from stream
`procedure SetBlobData();` |  | Set BLOB data
`procedure SetData();` |  | Set the parameter value from a buffer
`property AsBCD: Currency; [rw]` |  | Get or set parameter value as BCD value
`property AsBlob: TBlobData; [rw]` |  | Return parameter value as a blob
`property AsBoolean: Boolean; [rw]` |  | Get/Set parameter value as a boolean value
`property AsBytes: TBytes; [rw]` |  | Get or set parameter value as TBytes
`property AsCurrency: Currency; [rw]` |  | Get/Set parameter value as a currency value
`property AsDate: TDateTime; [rw]` |  | Get/Set parameter value as a date (TDateTime) value
`property AsDateTime: TDateTime; [rw]` |  | Get/Set parameter value as a date/time (TDateTime) value
`property AsFloat: Double; [rw]` |  | Get/Set parameter value as a floating-point value
`property AsInteger: LongInt; [rw]` |  | Get/Set parameter value as an integer (32-bit) value
`property AsLargeInt: LargeInt; [rw]` |  | Get/Set parameter value as a 64-bit integer value
`property AsMemo: string; [rw]` |  | Get/Set parameter value as a memo (string) value
`property AsSmallInt: LongInt; [rw]` |  | Get/Set parameter value as a smallint value
`property AsString: string; [rw]` |  | Get/Set parameter value as a string value
`property AsAnsiString: AnsiString; [rw]` |  | Parameter contents as an ANSI string
`property AsUTF8String: UTF8String; [rw]` |  | Parameter contents as an UTF8 string
`property AsUnicodeString: UnicodeString; [rw]` |  | Parameter contents as a Unicode string
`property AsTime: TDateTime; [rw]` |  | Get/Set parameter value as a time (TDateTime) value
`property AsWord: LongInt; [rw]` |  | Get/Set parameter value as a word value
`property AsFMTBCD: TBCD; [rw]` |  | Parameter value as a BCD value
`property Bound: Boolean; [rw]` |  | Is the parameter value bound (set to fixed value)
`property Dataset: TDataSet; [r]` |  | Dataset to which this parameter belongs
`property IsNull: Boolean; [r]` |  | Is the parameter empty
`property NativeStr: string; [rw]` |  | No description available
`property Text: string; [rw]` |  | Read or write the value of the parameter as a string
`property AsWideString: WideString; [rw]` |  | Get/Set the value as a widestring
`published`
`property DataType: TFieldType; [rw]` |  | Data type of the parameter
`property Name: string; [rw]` |  | Name of the parameter
`property NumericScale: Integer; [rw]` |  | Numeric scale
`property ParamType: TParamType; [rw]` |  | Type of parameter
`property Precision: Integer; [rw]` |  | Precision of the BCD value
`property Size: Integer; [rw]` |  | Size of the parameter
`property Value: Variant; [rws]` |  | Value as a variant
`end;`

## Inheritance

`TParam` |  | Parameter description class
`TCollectionItem`
`TPersistent,IFPObserved`
`TObject`

## Description

TParam is one item in a TParams collection. It describes the name (TParam.Name), type (ParamType) and value (TParam.Value) of a parameter in a parameterized query or stored procedure. Under normal circumstances, it should never be necessary to create a TParam instance manually; the TDataset descendent that owns the parameters should have created all necessary TParam instances.

## See also

TParams |  | A collection of parameter values for SQL-based datasets