[SOLVED] Copy a record ?
lazarus / 16-Databases

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TheNick · 2021-05-25 13:43

Hi all,
I'm trying to make a copy of an existing record into the same dataset
with some entries changed.

1) I copy the contents to a XML-file with the SaveToFile-procedure
2) I append a a new record to the dataset
3) I now populate the dataset with the old data by using the
LoadFromFile-procedure
4) I post the new record and set the mode to edit
5) I change some data

No matter what I do, I end up with empty data. The code looks
something like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i DataModuleR
ules.SQLSelectRulesList.SaveToFile('SQLSelectRulesList.xml', dfXML);
 //This generates a nice XML-
file DataModuleRules.SQLSelectRulesList.Append; if
FileExists('SQLSelectRulesList.xml') Then       DataModuleRules.SQLSel
ectRulesList.LoadFromFile('SQLSelectRulesList.xml'); //The file are
being read but nothing happens... DataModuleRules.SQLSelectRulesList.P
ost;DataModuleRules.SQLSelectRulesList.Edit;DataModuleRules.SQLSelectR
ulesList.FieldByName('name').AsString:='Copy from - '+
DataModuleRules.SQLSelectRulesList.FieldByName('name').AsString;  
Anyone got an idea what is going wrong?

//Cheers Niclas

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Zvoni · 2021-05-25 14:35

Is it just me, or is there an "ApplyUpdate" missing?

EDIT: And shouldn't the LoadFromFile also have a Format specified?
https://www.freepascal.org/docs-
html/fcl/bufdataset/tcustombufdataset.loadfromfile.html

EDIT2: Why don't you use "CopyFromDataset"?
https://www.freepascal.org/docs-
html/fcl/bufdataset/tcustombufdataset.copyfromdataset.html

EDIT3: another one: Why not use "INSERT INTO SELECT"?
https://www.w3schools.com/sql/sql_insert_into_select.asp

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egsuh · 2021-05-26 07:15

How to copy is your choice depending on your application's conditions,
but I would suggest to use SQL statement itself to copy records. 
Following is an example from Firebird documentation.

Code: SQL  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i INSERT INTO
Members (NUMBER, name)  SELECT NUMBER, name FROM NewMembers WHERE
Accepted = 1    UNION  SELECT NUMBER, name FROM SuspendedMembers WHERE
Vindicated = 1
And then you may change the data of copied records.

Of course this is an option.

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TheNick · 2021-05-26 09:01

Thank you both for your examples and suggestions. From my pov a safe
way of doing this (without defining to much stuff around) is by doing
a classic record:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  with
(rulerecord) do         begin              name:='Copy of - ' +
DataModuleRules.SQLSelectRulesList.FieldByName('name').AsString;     
       FAIClass:=
DataModuleRules.SQLSelectRulesList.FieldByName('class').AsString;    
        typeofcomp:=DataModuleRules.SQLSelectRulesList.FieldByName('ty
pe').AsString;              created_at:=TimeStamp;             
DataModuleRules.SQLSelectRulesList.Append;              DataModuleRule
s.SQLSelectRulesList.FieldByName('name').AsString:=name;             
DataModuleRules.SQLSelectRulesList.FieldByName('created_at').AsLargeIn
t:=created_at;              DataModuleRules.SQLSelectRulesList.FieldBy
Name('class').AsString:=FAIclass;              DataModuleRules.SQLSele
ctRulesList.FieldByName('type').AsString:=typeofcomp;         end;   
Can't say that I like it but it works. I was having higher hopes for
the 'CopyFromDataSet' but that costed more of effort then to create an
record-type (I have probably not figured out yet how to use in a
correct way!).

Cheers Niclas

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Zvoni · 2021-05-26 09:25

If i read it right, your SQLSelectRulesList is already of Type
DataSet, (Is it a DataSource/TSQLQuery?)
so it would be something like

DataModuleRules.SQLSelectRulesList.CopyFromDataSet(DataModuleRules.SQL
SelectRulesList.DataSet, True);

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TheNick · 2021-05-26 11:10

Quote from: Zvoni on May 26, 2021, 11:25:22 amIf i read it right, your
SQLSelectRulesList is already of Type DataSet, (Is it a
DataSource/TSQLQuery?)
so it would be something like

DataModuleRules.SQLSelectRulesList.CopyFromDataSet(DataModuleRules.SQL
SelectRulesList.DataSet, True);

True, it is an TSQLQuery.

I will try, what you suggested, in my other copydata-procedures.

Thanks,
Niclas