通用查询组件设计（续）

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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;