Sql + математика

sql.Text := 'UPDATE SKZ_Oscillogramm ' +
  'SET voltageRabochee = AVG(voltage) - voltage ' +
  'WHERE ukzNumber = :ukzN';
  Parameters.ParamByName('ukzN').Value := ukzNumber.Text;
  ExecSQL;

sql.Text := 'UPDATE SKZ_Oscillogramm ' +
  'SET voltageRabochee = (SELECT AVG(voltage) FROM SKZ_Oscillogramm WHERE ukzNumber = :ukzN) - voltage ' +
  'WHERE ukzNumber = :ukzN';

sql.Text := 'INSERT INTO UKZinfo (ukzNumber, VoltageAvg, VoltageMax, VoltageMin, CurrentAvg, ' +
      'CurrentMax, CurrentMin, PotentialAvg, PotentialMax, PotentialMin) ' +
      'SELECT ukzNumber, ' +
      'AVG(sutVoltage) AS VoltageAvg, ' +
      'MAX(sutVoltage) AS VoltageMax, ' +
      'MIN(sutVoltage) AS VoltageMin, ' +
      'AVG(sutCurrent) AS CurrentAvg, ' +
      'MAX(sutCurrent) AS CurrentMax, ' +
      'MIN(sutCurrent) AS CurrentMin, ' +
      'AVG(sutPotential) AS PotentialAvg, ' +
      'MAX(sutPotential) AS PotentialMax, ' +
      'MIN(sutPotential) AS PotentialMin ' +
      'FROM SKZ_sutochnye ' +
      'WHERE ukzNumber = :ukzN';
      Parameters.ParamByName('ukzN').Value := ukzNumber.Text;
    ExecSQL;

function OpenFDQuery(Q:TFDQuery; const SQL:String; Silent:Boolean=False):Boolean;
begin
try
Q.Close;
Q.SQL.Clear;
Q.SQL.Add(SQL);
Q.Open;
Result:=True;
except
Result:=False;
if not Silent then raise;
end;
 
end;

procedure TDM.OpenMachineParams(Filter: Integer);
var S:String;
begin
QMachineParams.Close;
S:='''
  Select MachineParameter.stdNr, MachineParameter.nameID, MachineParameter.descriptionID,
  T.text as Name, MachineParameter.refValue, MachineParameter.Min, MachineParameter.Max,
 T2.Text as MeasUnit, MachineParameter.tagID, Tag.TagName, T1.text as Description
From MachineParameter
Left Join Translation T on MachineParameter.nameID=T.textID
Left Join Translation T1 on MachineParameter.descriptionID=T1.textID
Left Join Translation T2 on MachineParameter.engUnitID=T2.textID
Left Join Tag on MachineParameter.tagID=Tag.tagID
Where (T.languageID=5) and (T1.languageID=5) and
  (T2.languageID=5) and (MachineParameter.hide=0)
''';
//Фильтр сюда
if Filter<>0 then
  S:=S+' and MachineParameter.mpID in '+
  '(Select mpID from MachineParameterClassMember Where parameterClassID='+
  Filter.ToString+') ';
S:=S+' Order BY MachineParameter.stdNr';
OpenFDQuery(QMachineParams,S);
end;