IB BlobFelder in TDBMemo funktioniert nicht

[Gustav Tham]

Hallo! Ich habe ein Problem
1. IB Tabelle enthält eine Spalte vom Typ BLOB.
2. Eine TDBMemo Komponente ist über eine TIBTabele Komponente mit diesem Feld verbunden.
Immer wenn ich versuche zu speichern oder etwas zu verändern bekomme ich eine Fehlermeldung, daß der Datentyp der TField Komponente nicht in einen Text umgewandelt werden kann.
Frage:
Hat das etwas mit den seltsamen SubTypes im DBExplorer zu tun?
Was ist das überhaupt?

[Andreas Kosch]

Hallo,

das folgende Beispiel (das nur über den Objektinspektor konfiguriert werden muss) demonstriert, wie man auf die BLOB-Spalte der Tabelle JOB in der Delphi-Beispieldatenbank <i>employee.gdb</i> zugreift:
<pre>
object Form1: TForm1
Left = 329
Top = 122
Width = 696
Height = 480
Caption = 'Form1'
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'MS Sans Serif'
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object Label1: TLabel
Left = 8
Top = 88
Width = 56
Height = 13
Caption = 'JOB_CODE'
FocusControl = DBEdit1
end
object Label2: TLabel
Left = 8
Top = 128
Width = 64
Height = 13
Caption = 'JOB_GRADE'
FocusControl = DBEdit2
end
object Label3: TLabel
Left = 8
Top = 168
Width = 79
Height = 13
Caption = 'JOB_COUNTRY'
FocusControl = DBEdit3
end
object Label4: TLabel
Left = 8
Top = 208
Width = 56
Height = 13
Caption = 'JOB_TITLE'
FocusControl = DBEdit4
end
object Label5: TLabel
Left = 8
Top = 248
Width = 68
Height = 13
Caption = 'MIN_SALARY'
FocusControl = DBEdit5
end
object Label6: TLabel
Left = 8
Top = 288
Width = 71
Height = 13
Caption = 'MAX_SALARY'
FocusControl = DBEdit6
end
object Label7: TLabel
Left = 8
Top = 328
Width = 106
Height = 13
Caption = 'JOB_REQUIREMENT'
FocusControl = DBMemo1
end
object DBEdit1: TDBEdit
Left = 8
Top = 104
Width = 69
Height = 21
DataField = 'JOB_CODE'
DataSource = DataSource1
TabOrder = 0
end
object DBEdit2: TDBEdit
Left = 8
Top = 144
Width = 134
Height = 21
DataField = 'JOB_GRADE'
DataSource = DataSource1
TabOrder = 1
end
object DBEdit3: TDBEdit
Left = 8
Top = 184
Width = 199
Height = 21
DataField = 'JOB_COUNTRY'
DataSource = DataSource1
TabOrder = 2
end
object DBEdit4: TDBEdit
Left = 8
Top = 224
Width = 329
Height = 21
DataField = 'JOB_TITLE'
DataSource = DataSource1
TabOrder = 3
end
object DBEdit5: TDBEdit
Left = 8
Top = 264
Width = 134
Height = 21
DataField = 'MIN_SALARY'
DataSource = DataSource1
TabOrder = 4
end
object DBEdit6: TDBEdit
Left = 8
Top = 304
Width = 134
Height = 21
DataField = 'MAX_SALARY'
DataSource = DataSource1
TabOrder = 5
end
object DBMemo1: TDBMemo
Left = 8
Top = 344
Width = 185
Height = 89
DataField = 'JOB_REQUIREMENT'
DataSource = DataSource1
TabOrder = 6
end
object DBNavigator1: TDBNavigator
Left = 56
Top = 56
Width = 240
Height = 25
DataSource = DataSource1
TabOrder = 7
end
object IBDatabase1: TIBDatabase
Connected = True
DatabaseName = 'C:\Database\IB\employee.gdb'
Params.Strings = (
'user_name=SYSDBA'
'password=masterkey'
'lc_ctype=ISO8859_1')
LoginPrompt = False
DefaultTransaction = IBTransaction1
IdleTimer = 0
SQLDialect = 1
TraceFlags = []
Left = 8
Top = 8
end
object IBTransaction1: TIBTransaction
Active = True
DefaultDatabase = IBDatabase1
AutoStopAction = saNone
Left = 8
Top = 40
end
object IBDataSet1: TIBDataSet
Database = IBDatabase1
Transaction = IBTransaction1
BufferChunks = 1000
CachedUpdates = False
DeleteSQL.Strings = (
'delete from JOB'
'where'
' JOB_CODE = :OLD_JOB_CODE and'
' JOB_GRADE = :OLD_JOB_GRADE and'
' JOB_COUNTRY = :OLD_JOB_COUNTRY')
InsertSQL.Strings = (
'insert into JOB'
' (JOB_TITLE, MIN_SALARY, MAX_SALARY, JOB_REQUIREMENT)'
'values'
' (:JOB_TITLE, :MIN_SALARY, :MAX_SALARY, :JOB_REQUIREMENT)')
RefreshSQL.Strings = (
'Select '
' JOB_CODE,'
' JOB_GRADE,'
' JOB_COUNTRY,'
' JOB_TITLE,'
' MIN_SALARY,'
' MAX_SALARY,'
' JOB_REQUIREMENT,'
' LANGUAGE_REQ'
'from JOB '
'where'
' JOB_CODE = :JOB_CODE and'
' JOB_GRADE = :JOB_GRADE and'
' JOB_COUNTRY = :JOB_COUNTRY')
SelectSQL.Strings = (
'select * from JOB')
ModifySQL.Strings = (
'update JOB'
'set'
' JOB_TITLE = :JOB_TITLE,'
' MIN_SALARY = :MIN_SALARY,'
' MAX_SALARY = :MAX_SALARY,'
' JOB_REQUIREMENT = :JOB_REQUIREMENT'
'where'
' JOB_CODE = :OLD_JOB_CODE and'
' JOB_GRADE = :OLD_JOB_GRADE and'
' JOB_COUNTRY = :OLD_JOB_COUNTRY')
Active = True
Left = 48
Top = 8
object IBDataSet1JOB_CODE: TIBStringField
FieldName = 'JOB_CODE'
Origin = 'JOB.JOB_CODE'
Required = True
Size = 5
end
object IBDataSet1JOB_GRADE: TSmallintField
FieldName = 'JOB_GRADE'
Origin = 'JOB.JOB_GRADE'
Required = True
end
object IBDataSet1JOB_COUNTRY: TIBStringField
FieldName = 'JOB_COUNTRY'
Origin = 'JOB.JOB_COUNTRY'
Required = True
Size = 15
end
object IBDataSet1JOB_TITLE: TIBStringField
FieldName = 'JOB_TITLE'
Origin = 'JOB.JOB_TITLE'
Required = True
Size = 25
end
object IBDataSet1MIN_SALARY: TFloatField
FieldName = 'MIN_SALARY'
Origin = 'JOB.MIN_SALARY'
Required = True
end
object IBDataSet1MAX_SALARY: TFloatField
FieldName = 'MAX_SALARY'
Origin = 'JOB.MAX_SALARY'
Required = True
end
object IBDataSet1JOB_REQUIREMENT: TMemoField
FieldName = 'JOB_REQUIREMENT'
Origin = 'JOB.JOB_REQUIREMENT'
BlobType = ftMemo
Size = 8
end
end
object DataSource1: TDataSource
DataSet = IBDataSet1
Left = 336
Top = 224
end
end
</pre>
Diese Spalte JOB_REQUIREMENT der Tabelle JOB ist als <b>BLOB SUB_TYPE TEXT</b> gekennzeichnet, so dass die InterBase-Tools dort nur darstellbare Zeichen erwarten. Auf die Datenspeicherung selbst hat dies jedoch keine Einfluss.<br>
Legt man in Delphi über den Feldeditor für die TIBDataSet-Instanz <i>persistente TField-Instanzen</i> an, nutzt IBX für die BLOb-Spalte den Typ <b>TMemoField</b>