begin
with ADOQuery1 do
begin
close;
SQL.Text := 'select Image1 from t_1 where id = 1';
Open;
TBlobFile(Fields[0]).SaveToFile('xxxx.bmp');
或者//TBlobFile(FieldByName('Image1')).SaveToFile('xxxx.bmp');
Close;
end;
end;
with ADOQuery1 do
begin
close;
SQL.Text := 'select Image1 from t_1 where id = 1';
Open;
TBlobFile(Fields[0]).SaveToFile('xxxx.bmp');
或者//TBlobFile(FieldByName('Image1')).SaveToFile('xxxx.bmp');
Close;
end;
end;
with ADOQuery1 do
begin
close;
SQL.Text := 'select Image1 from t_1 where id = 1';
Open;
TBlobFile(Fields[0]).LoadFromFile('xxxx.bmp');
Close;
end;
end;
DELPHI存取JPEG文件到SQL Server数据库
高红岩(ghyghost)
近日笔者书写一个小型的学生管理系统时,需要用到ADO控件存取SQL Server数据库图片,查看资料发现基本都是针对BMP文件进行操作(巨增数据库大小),但发现了★eagletian★高手翻译的ADO英文技术文档,里面涉及到了数据库存取JPEG文件的关键技术,在win98+sql server桌面版中测试通过,运行良好,现于源码公开如下:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, DBCtrls, Grids, DBGrids, Db, ADODB,jpeg, StdCtrls,dbtables;
{一定要USES JPEG单元,使能存储JPG文件格式}
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 < ghy.Size) do
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.如果数据库中要存储的是BMP文件,则在procedure TForm1.showbuttonClick(Sender: TObject);过程中代码更改如下即可存储显示BMP文件格式的操作。
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;
到此用DELPHI存取JPEG文件到SQL Server数据库中的具体操作已经叙述完毕。
begin
if OpenPictureDialog1.Execute then
Image1.Picture.LoadFromFile(OpenPictureDialog1.FileName);
end;procedure TForm1.Button2Click(Sender: TObject);
begin
ADOTable1.Append;
TBlobField(ADOTable1.FieldByName('FImage')).LoadFromFile(OpenPictureDialog1.FileName);
ADOTable1.Post;
end;
就可以了
1、建立过程
CREATE PROCEDURE sp_textcopy (
@srvname varchar (30),
@login varchar (30),
@password varchar (30),
@dbname varchar (30),
@tbname varchar (30),
@colname varchar (30),
@filename varchar (30),
@whereclause varchar (40),
@direction char(1))
AS
DECLARE @exec_str varchar (255)
SELECT @exec_str =
'textcopy /S ' + @srvname +
' /U ' + @login +
' /P ' + @password +
' /D ' + @dbname +
' /T ' + @tbname +
' /C ' + @colname +
' /W "' + @whereclause +
'" /F ' + @filename +
' /' + @direction
EXEC master..xp_cmdshell @exec_str 2、建表和初始化数据
create table 表名 (编号 int,image列名 image)
go
insert 表名 values(1,0x)
insert 表名 values(2,0x)
go3、读入
sp_textcopy '你的服务器名','sa','你的密码','库名','表名','image列名','c:\图片.bmp','where 编号=1','I' --注意条件是 编号=1sp_textcopy '你的服务器名','sa','你的密码','库名','表名','image列名','c:\bb.doc','where 编号=2','I' --注意条件是 编号=2go4、读出成文件
sp_textcopy '你的服务器名','sa','你的密码','库名','表名','image列名','c:\图片.bmp','where 编号=1','O' --注意条件是 编号=1sp_textcopy '你的服务器名','sa','你的密码','库名','表名','image列名','c:\bb.doc','where 编号=2','O' --注意条件是 编号=2
go
MSSQL MVP 大力作