Recently, the author writes a small student management system, you need to use the ADO control to access the SQL Server database picture, see the information found to operate the BMP file (the mass increase database size), but found ★ Eagletian ★ master translation ADO English Technical Documentation, involving key technologies for data inventory JPEG files, tested in Win98 SQL Server desktop version, good operation, is now disclosed in the source code:
Unit unit1;
Interface
Uses
Windows, Messages, Sysutils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, Dbctrls, Grids, DBGRIDS, DB, ADODB, JPEG, Stdctrls, DBTABLES
{Must use the USES JPEG unit, enable storage JPG file format}
Type
TFORM1 = Class (TFORM)
DataSource1: TDataSource;
Adoquery1: TadoQuery;
DBGRID1: TDBGRID;
DBNAVIGATOR1: TDBNAVIGATOR;
Image1: timage;
SaveButton: tbutton;
Showbutton: tbutton;
OpenDialog1: TopEndialog;
AdoQuery1ID: Tintegerfield;
Adoquery1Pic: TBLOBFIELD;
Procedure SaveButtonClick (Sender: TOBJECT);
Procedure ShowButtonClick (Sender: TOBJECT);
Procedure DBNAVIGATOR1CLICK (Sender: Tobject; Button: TnaviGateBTN);
Private
{Private Declarations}
public
{Public declarations}
END;
VAR
FORM1: TFORM1;
IMPLEMENTATION
{$ R * .dfm}
Function JPEGSTARTSINBLOB (Picfield: TBLOBFIELD): Integer;
VAR
Ghy: tadoblobstream;
Buffer: Word;
HX: String;
Begin
RESULT: = -1;
Ghy: = tadoblobstream.create (picfield, bmread);
Try
While (result = -1) and (ghy.position 1 Begin Ghy.readbuffer (buffer, 1); HX: = INTTOHEX (Buffer, 2); IF HX = 'FF' THEN BEGIN Ghy.readbuffer (buffer, 1); HX: = INTTOHEX (Buffer, 2); IF hx = 'd8' Then Result: = ghy.position - 2 Else if hx = 'ff' Then ghy.position: = ghy.position-1; End; // IF End; // while Finally ghy.free End; // Try END; Procedure TFORM1.SAVEBUTTONCLICK (Sender: TOBJECT); VAR PicStream: tadoblobstream; Begin Adoquery1.edit; PicStream: = tadoblobstream.create (TBLOBFIELD (Adoquery1.fields [1]), BMWRITE); if Form1.Opendialog1.execute THEN Begin PICSTream.LoadFromFile (OpenDialog1.FileName); PICSTream.position: = 0; Adoquery1.edit; TBLOBFIELD (AdoQuery1.fields [1]). LoadFromstream (PICSTREAM); Adoquery1.post; END; END; Procedure TFORM1.SHOWBUTTONCLICK (Sender: TOBJECT); VAR Ghy: tadoblobstream; Pic: tjpegimage; Begin Ghy: = tadoblobstream.create (AdoQuery1PIC, BMREAD); Try Ghy.seek (JPEGSTARTSINBLOB (AdoQuery1Pic), SofromBeginning; Pic: = tjpegimage.create; Try Pic.LoadFromstream (GHY); Image1.picture.graphic: = Pic; Finally Pic.free; END; Finally ghy.free END; END; Procedure tForm1.dbnavigator1click (Sender: Tobject; Button: TnaviGateBTN); Begin IF button in [NBFirst, NbPrior, NBNext, NBLAST] THEN ShowButton.click; END; End. If the BMP file to be stored in the database is stored, then the code changes to the BMP file format can be stored as follows. Procedure TFORM1.SHOWBUTTONCLICK (Sender: TOBJECT); VAR Ghy: tadoblobstream; Pic: Tbitmap; Begin Ghy: = tadoblobstream.create (AdoQuery1PIC, BMREAD); Try {Ghy.seek (JPEGSTARTSINBLOB (AdoQuery1Pic), SOFROMBEGINNING Pic: = Tbitmap.create; Try Pic.LoadFromstream (GHY); Image1.picture.graphic: = Pic; Finally Pic.free; END; Finally ghy.free END; END; The specific operations that have been used to access the JPEG file in the SQL Server database with Delphi.
