Jesus Cardenas has sent us these two procedures to copy a record from a table to another.
The advantage that they offer is that the structures of the tables don't have to be same.
This procedure adds records from a source table to a destination table, making comparisons for the name of the fields. The destination table remain in edit state. This routine only works for the fields associated with the object TField. These you can include them using the object inspector.
procedure AppendFrom;
var
i : integer;
fldDest, fldSource : TField;
begin
with tblDest do begin
Append;
for i := 0 to FieldCount - 1 do
begin
fldDest := Fields[i];
if not (fldDest.ReadOnly or fldDest.Calculated) then
begin
fldSource := tblSource.FindField(fldDest.FieldName);
if assigned(fldSource) then
begin
fldDest.DataSet.Edit;
fldDest.AsString := fldSource.AsString
end
end
end;
{Post}
end
end;
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This other procedure, makes the same thing that the previous one, but instead of managing the fields TField, it uses all the fields of the table. The fields are compared by name between the table origin and the destination.
procedure AppendFromAllFields;
var
i : integer;
fldDest, fldSource : TField;
tblSource, tblDest : TTable;
begin
tblSource := nil;
tblDest := nil;
try
tblSource := TTable.Create(nil);
tblDest := TTable.Create(nil);
tblSource.DatabaseName := tblS.DatabaseName;
tblSource.TableName := tblS.TableName;
tblDest.DatabaseName := tblD.DatabaseName;
tblDest.TableName := tblD.TableName;
tblDest.Open;
tblSource.Open;
with tblDest do
begin
Append;
for i := 0 to FieldCount - 1 do
begin
fldDest := Fields[i];
if fldDest.AsString = '' then
begin
fldSource := tblSource.FindField(fldDest.FieldName);
if assigned(fldSource) then
fldDest.AsString := fldSource.AsString;
end;
end;
Post;
end;
finally
tblDest.Free;
tblSource.Free;
end;
end;
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Improvement sent by: C. Aguado (cesagu@teleline.es)
1. - if we have in an index a field of kind Time, we can have an error of repeated Index when using the method AsString, since this it rounds the hour to the format hh:mm:ss, without keeping in mind the miliseconds. I have him avoiding using it 'Value' instead of 'AsString'.
2. - when we copy the data of a field of a table that it is not marked as " Required " to another in that if he is, we obtain an exception if the field of the first chart is empty, for what it is necessary to check it and in such a case to introduce something in the one. I introduce a 0, what gives me good results for my use, but I don't know if it will always be correct.
The listing with the changes that I have made in the original code to correct both first you hit it is the following one:
if Assigned(fldSource) then
begin
fldDest.Dataset.Edit;
if fldSource.Isnull then
begin
if fldDest.Required and fldSource.Isnull then
fldDest.Value:= 0; {ojo con esto
ya que si hay campos vacios en una tabla y cambiamos esos
campos a requeridos, puede haber problemas al convertirlos.}
end else fldDest.Value:= fldSource.Value;
end;
end;
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Updated at 17/08/2000
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