Delphi写的一个简单的数据库操作代码

unit DbContext;

interface
uses Windows, SysUtils, IniFiles, DB, ADODB, Dialogs;
type
  TDbContext = class
  private
    _fileFullName: string;
    _connString: string;

  public
    IsOk: Boolean;
    Connection: TADOConnection;
    Query: TADOQuery;

    constructor Create(fileFullName: string); overload;
    constructor Create(); overload;
    destructor Destroy; override;
  end;

implementation

//带参构造函数

constructor TDbContext.Create(fileFullName: string);
const
  connStrTemplate = 'Provider=OraOLEDB.Oracle.1;Persist Security Info=False;User ID=%s;Password=%s;Data Source=(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = %s)(PORT = %s)))(CONNECT_DATA = (SERVICE_NAME = %s)))';
var
  iniFile: TIniFile;
  ip, port, sid, userName, password, fileName, filePath: string;
begin
  IsOk := False;
  _fileFullName := fileFullName;
  if FileExists(_fileFullName) then
  begin
    iniFile := TIniFile.Create(_fileFullName);
    ip := iniFile.ReadString('DataBase', 'ip', '127.0.0.1');
    port := iniFile.ReadString('DataBase', 'port', '1521');
    sid := iniFile.ReadString('DataBase', 'sid', 'orcl');
    userName := iniFile.ReadString('DataBase', 'userName', 'admin');
    password := iniFile.ReadString('DataBase', 'password', 'admin');
    _connString := Format(connStrTemplate, [userName, password, ip, port, sid]);

    //如果未分配
    if not Assigned(Connection) then
      Connection := TADOConnection.Create(nil);

    //打开连接
    if not Connection.Connected then
    begin
      Connection.ConnectionString := _connString;
      Connection.KeepConnection := True;
      Connection.LoginPrompt := False;
      Connection.Open;
    end;


    Query := TADOQuery.Create(nil);
    Query.Connection := Connection;
    IsOk := True;
  end
  else
    showMessage('找不到dbConfig.ini配置文件');
end;

//无参构造函数

constructor TDbContext.Create();
var filePath: string; fileFullName: string;
begin
  filePath := ExtractFilePath(Paramstr(0));
  fileFullName := filePath + 'dbConfig.ini';
  Create(fileFullName);
end;

//析构函数

destructor TDbContext.Destroy;
begin
  FreeAndNil(Query);
  FreeAndNil(Connection);

  //调用基类的析构函数
  inherited Destroy;
end;
end.

 

 

unit Edit;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, DBClient, DbContext, StdCtrls;

type
  TEditForm = class(TForm)
    ds1: TDataSource;
    lblId: TLabel;
    lblObjKey: TLabel;
    lblObjValue: TLabel;
    lblObjValue2: TLabel;
    edtId: TEdit;
    edtObjKey: TEdit;
    edtObjValue: TEdit;
    mmoObjValue2: TMemo;
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);

  private
    { Private declarations }
    _dbContex: TDbContext;
    _id: string;
  public
    { Public declarations }
    constructor Create(aOwner: TComponent; id: string); reintroduce; overload;
  end;




implementation

{$R *.dfm}

constructor TEditForm.Create(aOwner: TComponent; id: string);
begin
  _id := id;
  //调用基类的构造函数
  inherited Create(aOwner);

end;

procedure TEditForm.FormCreate(Sender: TObject);
var
  query: string;
  objValue2: string;
begin

  //创建实例
  _dbContex := TDbContext.Create();

  //如果创建连接失败
  if _dbContex.IsOk = False then
  begin
    Exit;
  end;

  ds1.DataSet := _dbContex.Query;

  query := 'select *  from spareparts_cache where id=:id';


  with _dbContex.Query do
  begin
    Close;
    SQL.Clear;
    Parameters.Clear;
    SQL.Add(query);
    Parameters.ParamByName('id').Value := _id;
    Open;

    edtId.Text := FieldByName('Id').Value;
    edtObjKey.Text := FieldByName('ObjKey').Value;
    edtObjValue.Text := FieldByName('ObjValue').Value;

    //blob大字段
     objValue2:= TBlobField(FieldByName('ObjValue2')).AsString();

     mmoObjValue2.Text:= objValue2;
  end;

end;

procedure TEditForm.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  FreeAndNil(_dbContex);
end;

end.

 dbConfig.ini：

[DataBase]
ip=xxx.xxx.xxx.xxx
port=1521
sid=xxx
password=xxx
userName=xxx