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Gelöst Cursor options when used with a local embedded Database

  1. Alex Lindsay
    Alex Lindsay
  2. Valentina Database ADK
  3. Samstag, Februar 16 2019, 06:08 PM
  4.  Abonnieren via E-Mail
I have some questions about the Cursor options when used with a local embedded Database with Xojo V4RB on Mac OS.

1. What is the difference between cursors on the client compared to the cursors on the server for embedded Database?
2. I got an error saying client cursors can't be read-write for an embedded Database, is this expected?
3. What is the preferred way for using cursors in an embedded database for Read-Only?
4. What is the preferred way for using cursors in an embedded database for Read-Write?
  1. ADK_V4RB_XOJO
  2. OS_MAC
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Ruslan Zasukhin
Ruslan Zasukhin Akzeptierte Antwort
Hi Alex,

1) You can read about this in our Valentina WIKI

* http://valentina-db.com/docs/dokuwiki/v9/doku.php?id=valentina:vcomponents:vclient:cursor_location
* http://valentina-db.com/docs/dokuwiki/v9/doku.php?id=valentina:vreasons:vdb:server-side_cursors
Referenzen
  1. http://valentina-db.com/docs/dokuwiki/v9/doku.php?id=valentina:vcomponents:vclient:cursor_location
  2. http://valentina-db.com/docs/dokuwiki/v9/doku.php?id=valentina:vreasons:vdb:server-side_cursors
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Ruslan Zasukhin
Ruslan Zasukhin Akzeptierte Antwort
2. yes.

* Client-side cursor means a COPY of records moved into RAM of a client computer.
In such way (and only) work e.g. MySQL, PostgreSQL.

When you need to update a record, you should build and execute UPDATE command.

I think this described in the second link pointed in the prev my answer.
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Alex Lindsay
Alex Lindsay Akzeptierte Antwort
Thanks Ruskin. I think I understand how the cursors work in a client/server configuration. Does it matter if it is an embedded DB using the ADK instead? Both the DB and the client are in the same process in that scenario.
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Ruslan Zasukhin
Ruslan Zasukhin Akzeptierte Antwort
With embedded - local DB you have no overhead of network.

So you can easy use Server-side cursors to have read-write access to their records.

This is much more comfortable and more effective, comparing to
- create a SQL string with UPDATE and execute it
- re-build cursor using the same SELECT command, to see changes.
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Alex Lindsay
Alex Lindsay Akzeptierte Antwort
Thanks Ruslan,

That's what I needed to know. I'll use Server cursors on any embedded embedded systems for read/write.
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