PARADOX的bytes屬性字段讀寫 |
尚未結案
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fanwei3
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hagar
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cxg
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kenspc
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Bytes Field 其實是個binary field, 雖然只存1-255的值. (不同点是bytes 為unformatted fixed size binary) 請參考以下解說
TBytesField is a persistent field object that encapsulates the fundamental behavior common to untyped binary fields. TBytesField introduces no new properties, methods, or events beyond those inherited from TField. TBytesField overrides the DataSize property and constructor to reflect the specifics of a field of type ftBytes. As with all persistent field objects, a TBytesField can be created at design-time using the Fields Editor or at runtime by calling the constructor for the class. Persistent field objects exist solely in the memory space of a Delphi application. Creating a persistent field object only creates an object in the application, and does not result in the creation of a field in a table. Fields in a table can be accessed without use of persistent field objects. Virtual field objects are created to provide access to a field when the field is referenced through such means as the TDataSet.Fields property or the TDataSet.FieldByName method. A bytes field value is a set of unformatted bytes of fixed size.
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fanwei3
一般會員 發表:2 回覆:2 積分:0 註冊:2004-10-24 發送簡訊給我 |
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hagar
版主 發表:143 回覆:4056 積分:4445 註冊:2002-04-14 發送簡訊給我 |
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fanwei3
一般會員 發表:2 回覆:2 積分:0 註冊:2004-10-24 發送簡訊給我 |
|
hagar
版主 發表:143 回覆:4056 積分:4445 註冊:2002-04-14 發送簡訊給我 |
看這樣行不行:
// 存 procedure TForm1.Button1Click(Sender: TObject); var v: Variant; begin v := VarArrayCreate([0, 2], varByte); v[0] := 2; v[1] := 4; v[2] := 5; Table1.FieldByName('TheBytesField').AsVariant := v; end; // 取 procedure TForm1.Button2Click(Sender: TObject); const msg = '第 %d 個值為 %s'; var i: integer; v: Variant; s: string; begin v := Table1.FieldByName('TheBytesField').AsVariant; for i := 0 to Table1.FieldByName('TheBytesField').DataSize - 1 do begin s := VarToStr(v[i]); Memo1.Lines.Add(Format(msg, [i 1, s])); end; end;-- 棒球是從兩出局開始的. |
cxg
中階會員 發表:116 回覆:192 積分:76 註冊:2004-02-12 發送簡訊給我 |
引言: 字段是用來保存數值的,不過是是幾個存在一起,取的時侯要分開 例如: 一個字段保存: A B C BYTES字段保存:2 4 5 取出來就是: A=2,B=4,C=5. 請指教procedure TForm1.Button1Click(Sender: TObject); var c : char; begin c := 'a'; table1.edit; table1.FieldByName('Field1').AsString := c; table1.Post; end; |
cxg
中階會員 發表:116 回覆:192 積分:76 註冊:2004-02-12 發送簡訊給我 |
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kenspc
一般會員 發表:1 回覆:20 積分:4 註冊:2004-12-09 發送簡訊給我 |
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