Delphi 判断ClientDataSet控件的UpdateStatus属性类型为 (usUnmodified, usModified, usInserted, usDeleted)）

Delphi 判断ClientDataSet控件的UpdateStatus属性类型为 (usUnmodified, usModified, usInserted, usDeleted)）

根据ClientDataSet控件的UpdateStatus属性类型为（usUnmodified, usModified, usInserted, usDeleted），解析并拼成相应的增、删和改操作语句：

实例如下：

// ATableName : 将要修改的表名

// APrimaryKey : 表的主键值

// AIsMulti : 数据中包含的表的个数

// ADelta : 更新的数据集

procedure TForm1.Save(const ATableName, APrimaryKey, AIsMulti: WideString;

ADelta: OleVariant; var ErrorMsg: WideString);

var

ActualFieldList: TStringList;

PrimaryFieldList: TStringList;

i: Integer;

FieldNameList: string; //字段名称列表

FieldValueList: string; //字段值列表

FieldNameValueList: string; //字段值=名称列表

SetValueList: string; //Set字段值=名称列表, update的Sql用

SqlStr: string;

//返回欲修改表的字段名称列表

procedure GetFieldNameList(const ATableName: string);

var

QueryStr: string;

begin

QueryStr := 'select * from ' + ATableName + ' where 1 = 0 ';

try

FClientDataSet.Data := FDBoperation.cdsGetDataForRead(QueryStr, ErrorMsg);

except

Exit;

end;

FClientDataSet.GetFieldNames(ActualFieldList);

end;

//返回欲修改表的 主键字段名称=值串

function GetPKValueList: string;

var

j: Integer;

ValueStr: string;

ResultStr: string;

begin

ResultStr := ' ';

for j := 0 to PrimaryFieldList.Count - 1 do

begin

with FClientDataSet do

begin

case FieldByName(PrimaryFieldList[j]).DataType of

ftString, ftDate, ftDateTime:

ValueStr := QuotedStr(FieldByName(PrimaryFieldList[j]).AsString);

ftInteger:

ValueStr := FieldByName(PrimaryFieldList[j]).AsString;

end;

end;

if j > 0 then

ResultStr := ResultStr + ' and ';

ResultStr := ResultStr + PrimaryFieldList[j] + ' = ' + ValueStr;

end;

Result := ResultStr;

end;

begin

if AIsMulti = '1 ' then //Delta中仅包含一个表的数据

begin

FDBoperation.cdsUpdateDate(ATableName, ADelta, ErrorMsg);

end

else

begin //Delta中包含多个表的数据

ActualFieldList := TStringList.Create;

PrimaryFieldList := TStringList.Create;

try

{=== 得到欲修改表的字段名称列表 ===}

GetFieldNameList(ATableName);

FClientDataSet.Data := ADelta;

FClientDataSet.First;

with FClientDataSet do

begin

while not Eof do

begin

case UpdateStatus of

usModified:

begin

SetValueList := ' Set ';

for i := 0 to FieldCount - 1 do

begin

//是欲修改表的字段之一

if ActualFieldList.IndexOf(Fields[i].FieldName) > -1 then

begin

case Fields[i].DataType of

ftString, ftDate, ftDateTime:

begin

if not Fields[i].IsNull then

SetValueList := SetValueList + Fields[i].FieldName

+ '= ' + QuotedStr(Fields[i].AsString) + ', ';

end;

ftInteger:

begin

if not Fields[i].IsNull then

SetValueList := SetValueList + Fields[i].FieldName

+ '= ' + Fields[i].AsString + ', ';

end;

end;

end;

end;

System.Delete(SetValueList, Length(SetValueList), 1);

SqlStr := 'update ' + ATableName + SetValueList + ' where ' + FieldNameValueList;

end;

usInserted:

begin

FieldNameList := ' ';

FieldValueList := ' ';

for i := 0 to FieldCount - 1 do

begin

//是欲修改表的字段之一

if ActualFieldList.IndexOf(Fields[i].FieldName) > -1 then

begin

FieldNameList := FieldNameList + Fields[i].FieldName + ', ';

if Fields[i].IsNull then

FieldValueList := FieldValueList + ' null, '

else begin

case Fields[i].DataType of

ftString, ftDate:

begin

FieldValueList := FieldValueList + QuotedStr(Fields[i].AsString) + ', ';

end;

ftInteger:

begin

FieldValueList := FieldValueList + Fields[i].AsString + ', ';

end;

end;

end;

end;

end;

//删除末尾的逗号

System.Delete(FieldNameList, Length(FieldNameList), 1);

System.Delete(FieldValueList, Length(FieldValueList), 1);

SqlStr := 'insert into ' + ATableName + '( ' + FieldNameList + ') '

+ ' values ( ' + FieldValueList + ') ';

end;

usUnmodified, usDeleted:

begin

{=== 得到欲修改表的主键字段名称列表 ===}

PrimaryFieldList.CommaText := APrimaryKey;

{=== 得到欲修改表的主键字段名称=值串 ===}

FieldNameValueList := GetPKValueList;

if UpdateStatus = usDeleted then

SqlStr := 'delete from ' + ATableName + ' where ' + FieldNameValueList;

end;

end;

if UpdateStatus <> usUnmodified then

begin

try

FDBoperation.ExecSql(SqlStr, ErrorMsg);

except

raise;

end;

end;

Next;

end;

end;

finally

ActualFieldList.Free;

PrimaryFieldList.Free;

end;

end;

end;