How to use BOOLEAN type in SELECT statement

You can definitely get Boolean value from a SELECT query, you just can't use a Boolean data-type.

You can represent a Boolean with 1/0.

CASE WHEN (10 > 0) THEN 1  ELSE 0 END (It can be used in SELECT QUERY)SELECT CASE WHEN (10 > 0) THEN 1  ELSE 0 END AS MY_BOOLEAN_COLUMN  FROM DUAL

Returns, 1 (in Hibernate/Mybatis/etc 1 is true). Otherwise, you can get printable Boolean values from a SELECT.

SELECT CASE WHEN (10 > 0) THEN 'true' ELSE 'false' END AS MY_BOOLEAN_COLUMN FROM DUAL

This returns the string 'true'.

You can build a wrapper function like this:

function get_something(name in varchar2,                   ignore_notfound in varchar2) return varchar2isbegin    return get_something (name, (upper(ignore_notfound) = 'TRUE') );end;

then call:

select get_something('NAME', 'TRUE') from dual;

It's up to you what the valid values of ignore_notfound are in your version, I have assumed 'TRUE' means TRUE and anything else means FALSE.

From documentation:

You cannot insert the values TRUE and FALSE into a database column. You cannot select or fetch column values into a BOOLEAN variable. Functions called from a SQL query cannot take any BOOLEAN parameters. Neither can built-in SQL functions such as TO_CHAR; to represent BOOLEAN values in output, you must use IF-THEN or CASE constructs to translate BOOLEANvalues into some other type, such as 0 or 1, 'Y' or 'N', 'true' or 'false', and so on.

You will need to make a wrapper function that takes an SQL datatype and use it instead.