BOOLEAN

SQL Language StructureCommon Language Elements

`BOOLEAN` Examples

Inserting and selecting

CREATE TABLE TBOOL (ID INT, BVAL BOOLEAN);
COMMIT;

INSERT INTO TBOOL VALUES (1, TRUE);
INSERT INTO TBOOL VALUES (2, 2 = 4);
INSERT INTO TBOOL VALUES (3, NULL = 1);
COMMIT;

SELECT * FROM TBOOL;
          ID    BVAL
============ =======
           1 <true>
           2 <false>
           3 <null>

Test for TRUE value

SELECT * FROM TBOOL WHERE BVAL;
          ID    BVAL
============ =======
           1 <true>

Test for FALSE value

SELECT * FROM TBOOL WHERE BVAL IS FALSE;
          ID    BVAL
============ =======
           2 <false>

Test for UNKNOWN value

SELECT * FROM TBOOL WHERE BVAL IS UNKNOWN;
          ID    BVAL
============ =======
           3 <null>

Boolean values in SELECT list

SELECT ID, BVAL, BVAL AND ID < 2
  FROM TBOOL;
          ID    BVAL
============ ======= =======
           1 <true>  <true>
           2 <false> <false>
           3 <null>  <false>

PSQL declaration with start value
```
DECLARE VARIABLE VAR1 BOOLEAN = TRUE;
```
Valid syntax, but as with a comparison with NULL, will never return any record

SELECT * FROM TBOOL WHERE BVAL = UNKNOWN;
SELECT * FROM TBOOL WHERE BVAL <> UNKNOWN;

Use of Boolean Against Other Data Types

Although BOOLEAN is not inherently convertible to any other data type, the strings 'true' and 'false' (case-insensitive) will be implicitly cast to BOOLEAN in value expressions.For example:

if (true > 'false') then ...

The value 'false' is converted to BOOLEAN.Any attempt to use the Boolean operators AND, NOT, OR and IS will fail.NOT 'False', for example, is invalid.

A BOOLEAN can be explicitly converted to and from string with CAST.UNKNOWN is not available for any form of casting.

Note	Other Notes The type is represented in the API with the `FB_BOOLEAN` type and `FB_TRUE` and `FB_FALSE` constants. The value `TRUE` is greater than the value `FALSE`.

BOOLEAN

BOOLEAN Examples

Use of Boolean Against Other Data Types

`BOOLEAN` Examples