我有一个函数,我从DB获取数据,我的测试数据集返回6500行(我从SQLText变量中提取格式化的SQL语句并将其作为测试运行),但是当我运行以下代码时Eof永远不会触发,我已经看到导入了超过10万行。
ADOQuery := TADOQuery.Create(nil);
ADOQuery.ConnectionString := CONNECT_STRING;
// Build SQL Query
SQLText := Format( 'Select Temp.Serial, Temp.QCSample , Temp.Scrap , Temp.StationID , Temp.Defect , Temp.AddData , Temp2.Serial as Parent_Serial ' +
'from TAB_ELEMENT as Temp ' +
'left join TAB_ELEMENT as Temp2 on Temp.Parent_Id = Temp2.Element_Id ' +
'where Temp.Batch_ID = %d and Temp.StationID = 0 ',[iSearchID]);
ADOQuery.SQL.Clear; // Clear query of garbage values
ADOQuery.SQL.Text := SQLText; // Add query text to query module
ADOQuery.Open;
// Handle Results
iIndexPos := 0;
tDataImport.BeginUpdate;
while not ADOQuery.Eof do
begin
tDataImport.Items[iIndexPos].Serial := ADOQuery.FieldByName('Serial').AsString;
tDataImport.Items[iIndexPos].QCStatus := ADOQuery.FieldByName('QCSample').AsBoolean;
tDataImport.Items[iIndexPos].Scrap := ADOQuery.FieldByName('Scrap').AsInteger;
tDataImport.Items[iIndexPos].StationID := ADOQuery.FieldByName('StationID').AsInteger;
tDataImport.Items[iIndexPos].Defect := ADOQuery.FieldByName('Defect').AsBoolean;
tDataImport.Items[iIndexPos].AddData := ADOQuery.FieldByName('AddData').AsString;
tDataImport.Items[iIndexPos].ParentSerial := ADOQuery.FieldByName('Parent_Serial').AsString;
inc(iIndexPos);
end;
因此,在夏季使用这些参数运行此查询时,我希望有6500行,当我运行它时,即使在处理了100k +行之后它也永远不会结束。
答案 0 :(得分:8)
Open()
将光标放在第一条记录上并相应地设置Eof
。您没有调用Next()
将光标前进到下一条记录并更新Eof
,因此您一遍又一遍地处理相同的记录:
ADOQuery.Open;
while not ADOQuery.Eof do
begin
//...
ADOQuery.Next; // <-- add this!
end;
另外,您应该使用参数化查询而不是格式化的SQL查询字符串。它在DB上更安全,更快速,更高效:
ADOQuery := TADOQuery.Create(nil);
ADOQuery.ConnectionString := CONNECT_STRING;
ADOQuery.SQL.Text := 'Select Temp.Serial, Temp.QCSample , Temp.Scrap , Temp.StationID , Temp.Defect , Temp.AddData , Temp2.Serial as Parent_Serial ' +
'from TAB_ELEMENT as Temp ' +
'left join TAB_ELEMENT as Temp2 on Temp.Parent_Id = Temp2.Element_Id ' +
'where Temp.Batch_ID = :iSearchID and Temp.StationID = 0 ';
with ADOQuery.Parameters.ParamByName('iSearchID') do
begin
DataType := ftInteger;
Value := iSearchID;
end;
ADOQuery.Open;
try
iIndexPos := 0;
tDataImport.BeginUpdate;
try
while not ADOQuery.Eof do
begin
tDataImport.Items[iIndexPos].Serial := ADOQuery.FieldByName('Serial').AsString;
tDataImport.Items[iIndexPos].QCStatus := ADOQuery.FieldByName('QCSample').AsBoolean;
tDataImport.Items[iIndexPos].Scrap := ADOQuery.FieldByName('Scrap').AsInteger;
tDataImport.Items[iIndexPos].StationID := ADOQuery.FieldByName('StationID').AsInteger;
tDataImport.Items[iIndexPos].Defect := ADOQuery.FieldByName('Defect').AsBoolean;
tDataImport.Items[iIndexPos].AddData := ADOQuery.FieldByName('AddData').AsString;
tDataImport.Items[iIndexPos].ParentSerial := ADOQuery.FieldByName('Parent_Serial').AsString;
inc(iIndexPos);
ADOQuery.Next;
finally
tDataImport.EndUpdate;
end;
end;
finally
ADOQuery.Close;
end;