SQL工厂法

表結構：

exeno caption params sqlcommand tablename

201 登錄 @loginname ftsring(20) select * from user where loginname=:loginname user

//author: cxg

unit MySQL;

interface

uses
SysUtils, ADODB, uFunction;

type
TMySQL = class(TObject)
private
    fExeNo: Integer;
    fCaption: string;
    fParams: string;
    fSqlcommand: string;
    fTablename: string;
    fQry: TADOQuery;
    fValueArr: array[0..49] of Variant; //最多支持50个参数
    procedure SetExeNo(Value: integer);
protected

public
    constructor Create;
    destructor Destroy; override;
    procedure AddParam(const aValue: Variant);
    //说明: 添加参数值
    //参数: const aValue: Variant -- 参数值
    function GetData: _Recordset; //非事务性查询
    procedure ExeSQL;              //事务性操作
    procedure BeginTrans;          //开始事务
    procedure CommitTrans;         //提交事务
    procedure RollbackTrans;       //回滚事务
    property ExeNo: Integer read fExeNo write SetExeNo; //SQL执行序号
end;

implementation

{ TMySQL }

procedure TMySQL.AddParam(const aValue: Variant);
begin
fValueArr[fQry.Parameters.Count] := aValue;
fQry.Parameters.AddParameter;
end;

procedure TMySQL.BeginTrans;
begin
fQry.Connection.BeginTrans;
end;

procedure TMySQL.CommitTrans;
begin
fQry.Connection.CommitTrans;
end;

constructor TMySQL.Create;
begin
inherited;
fQry := TADOQuery.Create(nil);
fQry.Connection := uFunction.GetConnection;
end;

destructor TMySQL.Destroy;
begin
FreeAndNil(fqry);
inherited;
end;

procedure TMySQL.ExeSQL;
var
i: Integer;
begin
with fQry do
begin
    Close;
    SQL.Clear;
    SQL.Text := fSqlcommand;
    if Parameters.Count > 0 then
      for i := 0 to Parameters.Count - 1 do
        Parameters[i].Value := fValueArr[i];
    ExecSQL;
end;
end;

function TMySQL.GetData: _Recordset;
var
i: Integer;
begin
Result := nil;
with fQry do
begin
    Close;
    SQL.Clear;
    SQL.Text := fSqlcommand;
    if Parameters.Count > 0 then
      for i := 0 to Parameters.Count - 1 do
        Parameters[i].Value := fValueArr[i];
    Open;
    Result := fQry.Recordset;
end;
end;

procedure TMySQL.RollbackTrans;
begin
fQry.Connection.RollbackTrans;
end;

procedure TMySQL.SetExeNo(Value: integer);
var
aQry: TADOQuery;
begin
fQry.Parameters.Clear;
fExeNo := Value;
aQry := TADOQuery.Create(nil);
aQry.Connection := uFunction.getconnection;
with aQry do
begin
    Close;
    SQL.Clear;
    SQL.Text := 'select * from [sql] where [exeno]=:exeno';
    Parameters.ParamByName('exeno').Value := fExeNo;
    Open;
    if not IsEmpty then
    begin
      fCaption := FieldByName('caption').AsString;
      fParams := FieldByName('params').AsString;
      fSqlcommand := FieldByName('sqlcommand').AsString;
      fTablename := FieldByName('tablename').AsString;
    end;
end;
aQry.Free;
end;