Dexterity developers often need to use temporary tables to perform tasks, such as displaying data in a different order, consolidating or totalling data, to store data while it is being edited, or to combine data from tables so it can be sorted using an index using fields from multiple tables.
Working with temporary tables in Dexterity can be a little difficult some times as you need to always pass the table buffer when calling functions or procedures. This is because if the table buffer is not passed, a new instance of the table buffer will be created and a new instance of a temporary table will actually be a completely new temporary table with no data in it.
This becomes more complex if you want call a procedure in the background. Procedures which are called in the background cannot have a table buffer as a parameter because it would be possible for the form or script that created the table buffer to be closed while the background procedure is still in the process queue. In this situation, you will have to use a "permanent" temporary or a memory table (see below for details).
Following is a description of the different types of temporary tables:
One of the common uses for temporary tables in the past was to allow for data to be sorted into an order that is not one of the keys on the table. This is no longer needed as it is now possible to create Virtual Keys using the assign as key command. See the Dexterity documentation for more information.
If you need a temporary table with the same definition as an existing table, you no longer need to create a duplicate table definition and change the Physical Name to "TEMP". Instead you can use the Table_OpenAsTemp(table table_name) command. See the documentation for details.
[Edit] There is also a new undocumented command which can create a new table buffer based off an existing table buffer or reference to a table buffer. The command returns the reference to the table buffer, the syntax is new_reference = Table_OpenNewBuffer(table(table_reference)). As this is currently undocumented, use of this is at your own risk. That said it is used extensively in the code that handles Word Template integration from the Report Writer.
I hope this explanation of the different types of temporary tables and when each type should be used is of value.
26-Oct-2010: Added information about Table_OpenNewBuffer command added in Dexterity 11.0. Also added links to Temp table error posts.
This was a very good and enlightening article. I've often wondered specifically about the different types of temporary tables and if I was using the right kind. Usually, the query would pass through my brain and I forged ahead. Now, it all makes sense!
Thank you David!
Posting from Vaidy Mohan at Dynamics GP - Learn & Discuss
Posting from Leslie Vail at the Dynamics Confessor Blogspot
Great article David, but what about Memory tables with a physical name of TEMP?
Good Question. as a Memory table is a Ctree table, I would say that a Temporary (Memory) table will behave the same as a Temporary (Ctree) table. You could always test it out if you want.
Posting from Mark Polino from DynamicAccounting.net
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