X# Runtime and VO SDK Reference
X# Runtime and VO SDK Reference
VO Namespace
DbServer Class
DbServer Methods
DbServer.Append Method
DbServer.AppendDB Method
DbServer.AppendDelimited Method
DbServer.AppendSDF Method
DbServer.Average Method
DbServer.BLOBDirectExport Method
DbServer.BLOBDirectGet Method
DbServer.BLOBDirectImport Method
DbServer.BLOBDirectPut Method
DbServer.BLOBExport Method
DbServer.BLOBGet Method
DbServer.BLOBImport Method
DbServer.BLOBRootGet Method
DbServer.BLOBRootLock Method
DbServer.BLOBRootPut Method
DbServer.BLOBRootUnlock Method
DbServer.ClearFilter Method
DbServer.ClearIndex Method
DbServer.ClearLocate Method
DbServer.ClearOrderScope Method
DbServer.ClearRelation Method
DbServer.ClearScope Method
DbServer.Close Method
DbServer.Commit Method
DbServer.ConstructUniqueAlias Method
DbServer.Continue Method
DbServer.CopyDB Method
DbServer.CopyDelimited Method
DbServer.CopySDF Method
DbServer.CopyStructure Method
DbServer.Count Method
DbServer.CreateIndex Method
DbServer.CreateOrder Method
DbServer.DataField Method
DbServer.Delete Method
DbServer.DeleteAll Method
DbServer.DeleteOrder Method
DbServer.Error Method
DbServer.Eval Method
DbServer.FIELDGET Method
DbServer.FieldGetBytes Method
DbServer.FieldGetFormatted Method
DbServer.FieldHyperLabel Method
DbServer.FieldInfo Method
DbServer.FieldName Method
DbServer.FieldPos Method
DbServer.FIELDPUT Method
DbServer.FieldPutBytes Method
DbServer.FieldSpec Method
DbServer.FieldStatus Method
DbServer.FieldSym Method
DbServer.FieldValidate Method
DbServer.FLOCK Method
DbServer.GetArray Method
DbServer.GetLocate Method
DbServer.GetLookupTable Method
DbServer.GoBottom Method
DbServer.GoTo Method
DbServer.GoTop Method
DbServer.INDEXKEY Method
DbServer.INDEXORD Method
DbServer.Info Method
DbServer.Join Method
DbServer.Locate Method
DbServer.LockCurrentRecord Method
DbServer.LockSelection Method
DbServer.NoIVarGet Method
DbServer.NoIVarPut Method
DbServer.Notify Method
DbServer.OrderDescend Method
DbServer.OrderInfo Method
DbServer.OrderIsUnique Method
DbServer.OrderKeyAdd Method
DbServer.OrderKeyCount Method
DbServer.OrderKeyDel Method
DbServer.OrderKeyGoTo Method
DbServer.OrderKeyNo Method
DbServer.OrderScope Method
DbServer.OrderSkipUnique Method
DbServer.Pack Method
DbServer.RDDINFO Method
DbServer.Recall Method
DbServer.RecallAll Method
DbServer.RecordInfo Method
DbServer.Refresh Method
DbServer.Reindex Method
DbServer.Relation Method
DbServer.Replace Method
DbServer.ResetNotification Method
DbServer.RLOCK Method
DbServer.RLockVerify Method
DbServer.Seek Method
DbServer.SELECT Method
DbServer.SetDataField Method
DbServer.SetFilter Method
DbServer.SetIndex Method
DbServer.SetOrder Method
DbServer.SetOrderCondition Method
DbServer.SetRelation Method
DbServer.SetSelectiveRelation Method
DbServer.Skip Method
DbServer.Sort Method
DbServer.Sum Method
DbServer.SuspendNotification Method
DbServer.Total Method
DbServer.UnLock Method
DbServer.Update Method
DbServer.Zap Method
Click or drag to resize

DbServer.BLOBGet Method

X#
Get the contents of a BLOB, identified by its memo field number.

Namespace:  VO
Assembly:  VORDDClasses (in VORDDClasses.dll) Version: 2.19
Syntax
Copy
 VIRTUAL METHOD BLOBGet(
	uField,
	nStart,
	nCount
) AS USUAL CLIPPER
Request Example View Source

Parameters

uField (Optional)
Type: Usual
The name, number, or symbol representing the position of the field in the database file structure.
nStart (Optional)
Type: Usual
The starting position in the memo field of the BLOB data. If nStart is positive, the starting position is relative to the leftmost character in uFieldPos. If nStart is negative, it is relative to the rightmost character in uFieldPos. If nStart is omitted, it is assumed to be 1.
nCount (Optional)
Type: Usual
The number of bytes of data to retrieve, beginning at nStart. If nCount is larger than the amount of data stored, excess data is ignored. If omitted, DBServer:BLOBGet() retrieves to the end of the data.

Return Value

Type: Usual
The BLOB data retrieved from the memo field. The data type of the return value depends on the actual data stored. Use ValType() or UsualType() to determine the data type. If the indicated field is not a memo field, DBServer:BLOBGet() returns NIL.
Remarks
Tip Tip
nStart and nCount apply to string data only. They are ignored for any other data types.
DBServer:BLOBGet() is very similar to DBServer:FieldGet(). However, because string type variables cannot be larger than 64KB, DBServer:FieldGet() will raise a runtime error when attempting to retrieve memo fields of this magnitude or greater. DBServer:BLOBGet() will also raise an error if you attempt to retrieve a field greater than this magnitude; however, you can retrieve any subset of the BLOB data by using an nCount less than 64KB.
Tip Tip
BLOB data less than 64KB can be retrieved from a memo field using standard means (for example, referring to the field by name in an expression or using the DBServer:FieldGet() method).
Examples
This example imports information from a word processing document into a field, then uses DBServer:BLOBGet() to extract the first 25 characters of the field:
X#
Copy
 1FUNCTION GetFirst25()
 2LOCAL nPos
 3LOCAL cStr AS STRING
 4LOCAL oDBCust := Customer{}
 5oDBCust := Customer{}
 6// Field that contains word processor documentation
 7nPos := oDBCust:FieldPos("WP_DOC")
 8// Import a file (can be larger than 64 KB), then obtain the
 9// first 25 characters to show to the user
10IF oDBCust:BLOBImport(nPos, "c:\app\temp.doc")
11cStr := oDBCust:BLOBGet(nPos, 1, 25)
12ELSE
13cStr := "Error: could not import file!"
14ENDIF
15oDBCust:Close()
16RETURN cStr
See Also