通用查询组件设计（续）
2006-02-04 13:45:59 来源：WEB开发网
通用查询组件设计(续)
作者：nxyc_twz@163.com
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设置默认的匹配类型
PRocedure TDBFilterDialog.SetDefaultMatchType(const Value: TDBFilterMatchType);
begin
//设置默认的匹配类型
FDefaultMatchType := Value;
if Assigned(FDialog) and not (csDesigning in ComponentState) then
case FDefaultMatchType of
fdMatchNone :
begin
FDialog.grpSearchType.ItemIndex := 0;
FDialog.cbxNonMatching.Checked := true;
end;
fdMatchRange:
FDialog.pgeCriteria.ActivePage := FDialog.tabByRange;
else
FDialog.grpSearchType.ItemIndex := Integer(FDefaultMatchType);
end;
end;
设置字段
procedure TDBFilterDialog.SetFields;
var
i, j, p : Integer;
field, display : String;
begin
//设置字段
FDialog.lstAllFields.Clear;//清除所有字段
if FFields.Count = 0 then
begin
for i := 0 to FDataSet.FieldList.Count - 1 do
if FDataSet.Fields[i].Visible then //定义查询字段
FDialog.lstAllFields.Items.AddObject(FDataSet.Fields[i].DisplayName,FDataSet.FieldList.Fields[i]);
end
else
for j := 0 to FFields.Count - 1 do
begin
p := Pos(';', FFields.Strings[j]);
field := Copy(FFields.Strings[j], 1, p - 1);
if p = Length(FFields.Strings[j]) then
display := field
else
display := Copy(FFields.Strings[j], p+1, Length(FFields.Strings[j]));
for i := 0 to FDataSet.FieldList.Count - 1 do
if FDataSet.FieldList.Fields[i].FieldName = field then
FDialog.lstAllFields.Items.AddObject(display, FDataSet.FieldList.Fields[i]);
end;
if FDialog.lstAllFields.Items.Count > 0 then
begin
FDialog.lstAllFields.ItemIndex := 0;
FDialog.FieldsListBoxClick(nil);//单击字段列表框
end;
end;
设置字段列表
procedure TDBFilterDialog.SetFieldsList(const Value: TStringList);
begin
//设置字段列表
FFields.Assign(Value);
end;
设置SQL
procedure TDBFilterDialog.SetOriginalSQL(const Value: TStrings);
var
i : Integer;
begin
//设置SQL语句
if FOriginalSQL.Text <> Value.Text then
begin
FOriginalSQL.Clear;
FOriginalSQL.AddStrings(Value);
if not (csLoading in ComponentState) then
FFields.Clear;
FDialog.NewSQL;//新建SQL查询
end;
for i := 0 to FOriginalVariables.Count - 1 do
TDBVariable(FOriginalVariables[i]).Free;//定义参数数据变量类
FOriginalVariables.Clear;
if TStrings(GetOrdProp(FDataSet, SQLProp)).Text = '' then
exit;
for i := 0 to TQuery(FDataSet).Params.Count - 1 do
FOriginalVariables.Add(TDBVariable.Create(TQuery(FDataSet).Params[i].Name, TQuery(FDataSet).Params[i].Value)); //定义参数数据变量类
SetFields;//设置字段
end;
恢复SQL
procedure TDBFilterDialog.RestoreSQL;
var
i : Integer;
begin
//恢复SQL语句
// Disable the controls while we are working
FDataSet.DisableControls;
FDataSet.Close;
// clear the existing SQL and variable declarations
// restore the original SQL and variables
SetOrdProp(FDataSet, SQLProp, Integer(FOriginalSQL));
if FDataSet is TDataSet then
for i := 0 to FOriginalVariables.Count - 1 do
TQuery(FDataSet).ParamByName(TDBVariable(FOriginalVariables[i]).VariableName).Value :=
TDBVariable(FOriginalVariables[i]).VariableValue
else
for i := 0 to FOriginalVariables.Count - 1 do
TQuery(FDataSet).ParamByName(TdBVariable(FOriginalVariables[i]).VariableName).Value :=
TDBVariable(FOriginalVariables[i]).VariableValue;
FDataSet.Open;
SetFields;
FDataSet.EnableControls;
FModifiedSQL.Assign(TStrings(GetOrdProp(FDataSet, SQLProp)));
end;
保存参数值
procedure TDBFilterDialog.SaveParamValues;
var
i : Integer;
begin
//保存参数值
if FDataSet is TDataSet then
for i := 0 to FOriginalVariables.Count - 1 do
TDBVariable(FOriginalVariables[i]).VariableValue :=
TQuery(FDataSet).ParamByName(TDBVariable(FOriginalVariables[i]).VariableName).Value
else
for i := 0 to FOriginalVariables.Count - 1 do
TDBVariable(FOriginalVariables[i]).VariableValue :=
TQuery(FDataSet).ParamByName(TDBVariable(FOriginalVariables[i]).VariableName).Value;
end;
装载过滤对话框
procedure TDBFilterDialog.Loaded;
var
i : Integer;
begin
inherited;
if Assigned(FDataSet) and not (csDesigning in ComponentState) then
begin
SetFields;
OriginalSQL.Assign(TStrings(GetOrdProp(FDataSet, SQLProp)));
for i := 0 to TQuery(FDataSet).Params.Count - 1 do
FOriginalVariables.Add(TDBVariable.Create(TQuery(FDataSet).Params[i].Name,
TQuery(FDataSet).Params[i].Value));
end;
end;
传送消息
procedure TDBFilterDialog.Notification(AComponent: TComponent;
Operation: TOperation);
begin
inherited;
if (AComponent = FDataset) and (Operation = opRemove) then
FDataset := nil;
end;
构造函数
constructor TDBFilterDialog.Create(AOwner: TComponent);
begin
//构造函数
inherited Create(AOwner);
FDialog := TMyDBFilterDialog.Create(self);
FOptions := [fdShowCaseSensitive, fdShowNonMatching];
FDefaultMatchType := fdMatchStart;
Caption := SDBFilterCaption;
FFields := TStringList.Create;
FOriginalSQL := TStringList.Create;
FModifiedSQL := TStringList.Create;
FOriginalVariables := TList.Create;
end;
析构函数
destructor TDBFilterDialog.Destroy;
var
i : Integer;
begin
FDialog.Free;
FFields.Free;
FOriginalSQL.Free;
FModifiedSQL.Free;
for i := 0 to FOriginalVariables.Count - 1 do
TDBVariable(FOriginalVariables[i]).Free;
FOriginalVariables.Free;
inherited Destroy;
end;
执行查询
function TDBFilterDialog.Execute : Boolean;
var
CurrentSQL : TStrings;
begin
//执行数据查询
CurrentSQL := TStrings(GetOrdProp(FDataSet, SQLProp));
// 检查SQL语句是否已经改变了
if not FModifiedSQL.Equals(CurrentSQL) then
OriginalSQL := CurrentSQL;
if FDialog.lstAllFields.Items.Count = 0 then
SetFields;
FDialog.grpSearchType.ItemIndex := Integer(FDefaultMatchType);
if fdShowCaseSensitive in Options then
FDialog.cbxCaseSensitive.Visible := true
else
FDialog.cbxCaseSensitive.Visible := false;
if fdShowNonMatching in Options then
FDialog.cbxNonMatching.Visible := true
else
FDialog.cbxNonMatching.Visible := false;
if fdCaseSensitive in Options then
FDialog.cbxCaseSensitive.Checked := true
else
FDialog.cbxCaseSensitive.Checked := false;
SaveParamValues;//保存参数值
Result := FDialog.ShowModal = mrOK; //点击确定按钮
if Result then
ReBuildSQL;//重建SQL语句
end;
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