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Queries and Cached Updates

Posted on 1997-12-11
Medium Priority
Last Modified: 2010-04-04
I run a query to select rows from a table (just one!)
based on user input. I then need to print the data from the selected rows.
The order is important, so I use an Order By clause which prevents me from
setting the RequestLive property to true. Finally, after each row is
printed, I mark the row as printed along with the date. This is important so
that if there is a printer error or other problem, the user would only need
to reprint from where they left off. The code is as follows:

1.    query the table
Select * from customertable where customernumber = :customernumb
2.    process the result
   While not Query1.eof do
           Query1.FieldByName('DATEBILLED').Value := Date;
           Query1.FieldByName('ACTCODE').Value := 3;     (***marks the row
as printed**)
3. update the rows as printed

At the MyDatabase.ApplyUpdates([Query1]) line I get an application error
with the message table is read only. I thought that is why you use a
TUpdateSQL component! I don't know if this helps you understand my problem
better or not. I have been struggling with this for awhile and would
appreciate any help. I am using Delphi 2.01 with a Paradox table.

Jay Eisenstock

Question by:jeisen
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Expert Comment

ID: 1353414
What is the contents of your UpdateSQL objects' modify property, and what are the key fields in the database?

Author Comment

ID: 1353415
In response to the question about the UpdateSQL Property:
update CustomerTable

I used the update SQL editor to generate the code. The key fields are CUSTOMER and CODENUMBER.

Accepted Solution

mvz121697 earned 400 total points
ID: 1353416
Cached update's is not supported for local table's like Paradox.
I think you should use a second query, whith an update statement for the customertable.
You can build this dynamicly with the values you read form your query1. In the where clause you use the primary key from query1. After this you have to reopen Query1 to see the results in this query.

Hope this helps.

Author Comment

ID: 1353417
I graded the answer C because I found a better solution. Here it is:
1  Change the original query to eliminate the "order by" clause and set "RequestLive" to true
2  Batch copy the query to a temporary table indexed by the values in the original "order by" clause
3  Process through the indexed table sequentially to print each value. Then, do a Locate on the query to update the values

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