[yunqa.de] Re: how to search for boolean value
- From: Delphi Inspiration <delphi@xxxxxxxx>
- To: yunqa@xxxxxxxxxxxxx
- Date: Tue, 30 Jun 2009 12:46:12 +0200
At 15:24 29.06.2009, Rael Bauer wrote:
>I have a field in sqlite database declared as BOOLEAN, and also set it's value
>with
>Dataset.FieldByName('bool_field').AsBoolean.
DISQLite3 does not have a BOOLEAN field type. If you declare a field as
BOOLEAN, DISQLite3 will assign a NUMERIC type affinity to it.
The recommended representation of boolean values is INTEGER: 1 stands for true,
0 = false. Storage for 0 and 1 values is optimized. The TDISQLite3UniDirQuery
class wrapper follows this recommendation.
>If I view the table in SQLite Spy then values show up as true or false.
Just like DISQLite3, SQLiteSpy does not know BOOLEAN values. I suppose you
should see 1 or 0, but not "true" of "false".
>How do I construct a sql statement to search on such a boolean value, e.g:
>select * from table where bool_field = TRUE.
Following the above recommendation, you should do it like this:
CREATE TABLE t (b INTEGER);
INSERT INTO t VALUES (1);
INSERT INTO t VALUES (0);
SELECT * FROM t WHERE b;
Ralf
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