Re: Upgrading a database through patching

> Stephane,
>
> I've dealt with the question of saving list info by creating a data  
> table to hold list information.  Then, prior to an update a set of  
> methods is run to copy the list info into the data table.  After  
> the update another set of methods is run to copy the data back from  
> the table into the lists.
>
> The drawbacks are that you have to be able to trigger the methods  
> and you must explicitly list all of the lists you want to save in  
> code.
>
> I use  'Prepare for update'  and 'Finish update' menu items to  
> trigger the code.  My update instructions to the users tell them to  
> use these buttons as part of the update process.
>
> Here's my code if you find it useful.
>
> Allen
>
>
> Table: Lists `this table holds the list name, list elements and  
> element position within the list
>
> Id: alpha 32  `this is the name of the list
> Item: alpha 80 `this is a list element
> Sequence: Longint `this is the item position in the list
>
> *************
>
> Method used to save an individual list:
>
> Method: Lists_Save_One
>   `saves the contents of a list into an array of records
>   `ham 7/99
>
> C_STRING(32;$sList_Name)
>
> $sList_Name:=$1
>
>   `remove old list contents from storage table
> MESSAGES OFF
> QUERY([Lists];[Lists]Id=$sList_Name)
> DELETE SELECTION([Lists])
>
> LIST TO ARRAY($sList_Name;$asList_Contents)  `save the current list  
> contents as an array
>
> For ($i;1;Size of array($asList_Contents))
> CREATE RECORD([Lists])
> [Lists]Id:=$sList_Name
> [Lists]Item:=$asList_Contents{$i}
> [Lists]Sequence:=$i  `keep track of the entry order
> SAVE RECORD([Lists])
> End for
>
> MESSAGES ON
>
> *******************
>
> Method: List_Load_One
>   `saves the contents of an array of records into a list
>   `ham 7/99
>
> C_STRING(32;$sList_Name)
>
> $sList_Name:=$1
>
>   `get list contents from storage table
> MESSAGES OFF
> QUERY([Lists];[Lists]Id=$sList_Name)
>
>   `only replace list contents if there is something
>   `to replace them with
> If (Records in selection([Lists])>0)
>
> ORDER BY([Lists];[Lists]Sequence;>)
>
> SELECTION TO ARRAY([Lists]Item;$asList_Contents)
> ARRAY TO LIST($asList_Contents;$sList_Name)
>
> Else
>  `this list has never been set - clear whatever might be in the  
> current list.
>  `this will clear the dev gus lists for departments which have  
> never initialized this list.
> ARRAY TEXT($atList_Contents;0)
> ARRAY TO LIST($atList_Contents;$sList_Name)
> End if
>
> MESSAGES ON
>
> ***********
> Method fragment to save my lists  (part of 'Prepare for update')
>
> LIST_Save_One ("Actions")
> LIST_Save_One ("Agencies")
> LIST_Save_One ("Agency_Division")
> LIST_Save_One ("Agency_HList")
>
> Method fragment to load the lists  (part of 'Finish update')
>
> LIST_Load_One ("Agencies")
> LIST_Load_One ("Agency_Division")
> LIST_Load_One ("Agency_HList")
> LIST_Load_One ("Agency_List")
>
>
>
>> Good day,
>>
>> I have created a database for a local group a few years ago. Since  
>> then, the users have added items to lists, added and modified  
>> users and passwords, etc.
>>
>> Now I want to provide them with an update I have done to the DB.  
>> However if I only send them a new structure file, they will loose  
>> all the users information, and all the list items. How can I  
>> update the DB without loosing all that?
>>
>> Can 4D create a patch to update only specific code? Or is there a  
>> 3rd party solution?
>>
>> Thank you,
>>
>> Stephane Potvin
>>
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>
> --
>
> ------------------------------
> Allen Matlick
> allen@...
> 805-893-5219
> ------------------------------
>
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