CREATE OR REPLACE FUNCTION _chkLogin(userid varchar,pwd varchar)
RETURNS BOOLEAN AS
$BODY$
DECLARE 
 passed BOOLEAN;
BEGIN
 SELECT  (_password = $2) FROM _vRegistration WHERE _userid = $1;
 RETURN passed;
END;
$BODY$
LANGUAGE 'plpgsql';

当我执行上面的代码时,我得到以下错误,

SELECT _chkLogin('username','abcd') as passed;

ERROR: query has no destination for
result data

我使用了执行,然后我得到一个不同的问题,

PERFORM _chkLogin('username','abcd');

ERROR: Syntax error at or near
“perform”

建议我应该怎么做才能克服这个错误.