Temporary Index on the fly

Posted on 1998-01-29
Last Modified: 2010-05-18
How would I go about creating a temporary Index in a procedure that can be used in a TTable, but then can be discarded (somehow) either automatically or manually when the Table is closed or freed?

Question by:Whytboy
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3

Accepted Solution

d4jaj1 earned 150 total points
ID: 1357849
Don't know of any way to create a temporay index, the best thing to do is create the index, then delete it when the table/form is closed.  To add the index, use;

if IndexName = Fieldname then ixCaseSensitive is reqd (the default)
if IndexName <> Fieldname then ixCaseInsensitive is reqd

Thus you need:

table.AddIndex('cusname', 'name', [ixCaseInsensitive]);
table.AddIndex('name', 'name', []);

To delete the Index, use; Table1.DeleteIndex('NewIndex');

Any questions, please add a comment.

Good Luck!

Author Comment

ID: 1357850
    Will this add the index to the table?  I ask, because basically, I have to keep everything READ-ONLY.  The table I am viewing and wanting to Re-Index is not of my own design and so I can't adjust the database in ANY way.  They have their indexes in the database, to which I can not add, modify, or delete!


Expert Comment

ID: 1357851
In that case, you have a problem.  There isn't a 'virual' index.  This will actually add an index to the table.

What do you need teh index for, sorting, filtering?
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!


Author Comment

ID: 1357852
Its for sorting mainly... on a non-primary key or indexed value.  I did try using a SQL with the fieldname as the ORDER BY parameter... but, it didnt work either.

Expert Comment

ID: 1357853
Unfortunately, the Order By clause uses an Index to sort the DB.  Every other means of sorting a table, SetRange, IndexName, etc. require an index - afterall, that what they are there for.  Unless the owners of the DB allow you to add an index - at least only for a short time, you won't be able to sort this table.

There is a way you can provide your users a sorted view of this same data, although it will be slow.  It would require you to create a new table, just like the existing table, copy its data, then sort (apply the index) to the newly created table.  Add a button you your existing form that opens a new form and creates the table ---

   with table1 do
   tempdb := ttable.create(nil);
    with tempdb do begin
     DataBaseName := table1.databasename;
     tableName := 'temporary.db';
     TableType := table1.tabletype;
     with IndexDefs do
       Add('NewIndex', 'NewIndex', []);

Set the index and show the form here.


Author Comment

ID: 1357854
Yeah... Thats about what I came down to.. now the problem is "sync"ing the tables..but, thats a different question

Expert Comment

ID: 1357855
You could create a new field in the table only for sorting and then when the user want to sort you could copy all fieldvalues to that "SortField"... Slow again ofcourse

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Are you ready to implement Active Directory best practices without reading 300+ pages? You're in luck. In this webinar hosted by Skyport Systems, you gain insight into Microsoft's latest comprehensive guide, with tips on the best and easiest way…

739 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question