TParadoxDataSet: what changed
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Title: TParadoxDataSet
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| 1 | + | > **Note:** Paradox uses the **BDE** (Borland Database Engine) that is unmaintained and unsupported since around 2000. | |
| 2 | + | ||
| 3 | + |  **TParadoxDataSet** is a [[TDataSet]] that can read (***but not write!***) Paradox files up to Version 7. | |
| 4 | + | ||
| 5 | + | Its main characteristics are : | |
| 6 | + | ||
| 7 | + | - Data-aware implementation, i.e. the component is a descendant of TDataset, and you can use the standard data-aware Lazarus components to display the table contents. | |
| 8 | + | - All table levels up to version 7 | |
| 9 | + | - No external DLL needed (unlike the [[TParadox]] component that comes with Lazarus). Works in 32- and 64-bit operating systems. | |
| 10 | + | - Now supports BLOB fields, character encoding, filtering and bookmarks. | |
| 11 | + | ||
| 12 | + | The motivation for having the component read-only is to provide a way to read old Paradox files for converting to newer database formats. | |
| 13 | + | ||
| 14 | + | ### Author/License | |
| 15 | + | ||
| 16 | + | - Author: Christian Ulrich | |
| 17 | + | - License: [Mozilla Public License 1.1](https://opensource.org/licenses/MPL-1.1), or [LGPL](http://www.opensource.org/licenses/lgpl-license.php) | |
| 18 | + | ||
| 19 | + | ### Download | |
| 20 | + | ||
| 21 | + | The latest stable release (v0.2) can be found at | |
| 22 | + | ||
| 23 | + | - [Lazarus CCR](https://sourceforge.net/projects/lazarus-ccr/files/Paradox%20DataSet/tparadoxdataset-v0.2.zip/download) | |
| 24 | + | ||
| 25 | + | ### Bug reporting / Feature Request | |
| 26 | + | ||
| 27 | + | Please report bugs to the [Lazarus Bugtracker](http://www.freepascal.org/mantis/set_project.php?project_id=3) in Category Packages | |
| 28 | + | ||
| 29 | + | ### SVN | |
| 30 | + | ||
| 31 | + | You can get the latest source via SVN: | |
| 32 | + | ||
| 33 | + | ``` bash | |
| 34 | + | svn checkout https://svn.code.sf.net/p/lazarus-ccr/svn/components/tparadoxdataset | |
| 35 | + | ``` | |
| 36 | + | ||
| 37 | + | ### Change Log | |
| 38 | + | ||
| 39 | + | - 31 January 2007 - Initial release | |
| 40 | + | - May 2019 - Update to current FPC/Lazarus versions, 64-bit, BLOB support, filtering, bookmarks, character encoding | |
| 41 | + | ||
| 42 | + | Status: Beta | |
| 43 | + | ||
| 44 | + | ### Installation | |
| 45 | + | ||
| 46 | + | - If needed, unzip the files from the zip file to any directory. | |
| 47 | + | - In Lazarus, open the package .lpk file with "Package" \> "Open package file (.lpk)". In v0.2 there are two packages; both have the same content, but **lazparadox.lpk** has a naming conflict with the [[TParadox|Paradox]] package contained in the Lazarus distribution; therefore it is recommended to install **lazparadoxpkg.lpk** instead. | |
| 48 | + | - If you don't want to install the component into the IDE, click on "Compile". | |
| 49 | + | - If you want to install the component into the IDE, click on "Use" \> "Install". Confirm the prompt to rebuild the IDE. When Lazarus restarts you'll find the component `TParadoxDataset` on palette "Data Access". | |
| 50 | + | ||
| 51 | + | ### Usage | |
| 52 | + | ||
| 53 | + | - Drop the `TParadoxDataset` component on the form. | |
| 54 | + | - Specify the name of the table file (extension ".db") in property `TableName` | |
| 55 | + | - Set `Active` to `true` in order to open the table. When, for example, a DBGrid is linked to the dataset the table is immediately displayed. | |
| 56 | + | - The **encoding** of text fields used in the file is displayed in the read-only property `InputEncoding`. It is automatically converted to the encoding given in property `TargetEncoding` which defaults to "UTF8". In the case that text fields must be encoded differently specify the codepage name here, e.g. "CP1252" for Western Europe code page (use the (case-insensitive) names given in the LazUtils unit *lconvencoding*). | |
| 57 | + | - **Filtering**: Set `Filtered` to `false`. Then define the filter conditon in property `Filter` or use the `OnFilterRecord` event. Finally start the filtering action by setting `Filtered` to `true`. | |
| 58 | + | - **Bookmarks**: Store the currently active record as a bookmark by setting the variable `bookmark` (which is of type `TBookmark` to `ParadoxDataset1.GetBookmark`. For returning to this record, call `ParadoxDataset1.GotoBookmark(boomark)`. Since the component uses the `RecNo` as bookmarks it is not required to call `FreeBookmark`. | |
| 59 | + | ||
| 60 | + | ## See also | |
| 61 | + | ||
| 62 | + | - [[TParadox]] | |
| 63 | + | ||
| 64 | + | --- | |
| 65 | + | *From the Free Pascal wiki, page "TParadoxDataSet", as it stood on 2019-05-12 after a change by Wp, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* | |
| 66 | + | Category: Components | |
| 67 | + | Category: Databases | |
| 68 | + | Category: Lazarus-CCR |