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Document CORE-726 - Boolean data type.

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asfernandes 2013-04-16 16:13:38 +00:00
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doc/WhatsNew
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@ -345,6 +345,8 @@
* New feature CORE-726
Boolean data type
See also:
/doc/README.data_types
Contributor(s):
Adriano dos Santos Fernandes <adrianosf at gmail.com>

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doc/sql.extensions/README.data_types
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@ -33,3 +33,50 @@ BIGINT (FB 1.5)
of SMALLINT shall be less than or equal to the precision of INTEGER,
and the precision of BIGINT shall be greater than or equal to the
precision of INTEGER.
BOOLEAN (FB 3.0)
--------------
Function:
SQL2008-compliant boolean type.
Author:
Adriano dos Santos Fernandes <adrianosf at gmail.com>
Syntax rules:
BOOLEAN
Storage:
8-bit
Example(s):
1. DECLARE VARIABLE VAR1 BOOLEAN = TRUE;
2. CREATE TABLE TABLE1 (FIELD1 BOOLEAN);
Note(s):
1. Quote from the SQL-99 specification:
The data type boolean comprises the distinct truth values TRUE and FALSE. Unless prohibited
by a NOT NULL constraint, the boolean data type also supports the truth value UNKNOWN as the
null value. This specification does not make a distinction between the null value of the
boolean data type and the truth value Unknown that is the result of an SQL <predicate>,
<search condition>, or <boolean value expression>; they may be used interchangeably to mean
exactly the same thing.
2. Represented in the API with the FB_BOOLEAN type and FB_TRUE and FB_FALSE constants.
3. The value TRUE is greater than the value FALSE.
4. Booleans are not implicitly convertible to any other datatype. But it's convertible to/from
strings with CAST.
5. It's allowed to test booleans without compare with TRUE or FALSE. For example,
"field1 OR field2" and "NOT field1" are valid expressions. It's also allowed to compare with
others operators, including the new IS operator: "field1 IS FALSE".
6. For compatibility reasons, the names INSERTING, UPDATING and DELETING (which aren't keywords)
works (like in 2.5 and previous) as boolean expressions and works as values (column or
variable) in non-booleans expressions. For example, in:
SELECT INSERTING, NOT INSERTING FROM TEST WHERE INSERTING AND INSERTING IS TRUE
the INSERTING's are respectively recognized as value, keyword, keyword and value.