Hi all,
I'm by no means a (My)SQL expert and just getting started working with
VIEWs and stored procedures, and now I'm puzzled by this behaviour:
DROP DATABASE `test`;
CREATE DATABASE `test`;
USE `test`;
CREATE TABLE `mytable`
(`ID` SERIAL,
`Type` INTEGER UNSIGNED NULL,
PRIMARY KEY (`ID`));
INSERT INTO `mytable` (`Type`) VALUES (NULL);
CREATE TABLE `types`
(`ID` SERIAL,
`Name` TEXT NOT NULL,
PRIMARY KEY (`ID`));
INSERT INTO `types` (`Name`) VALUES ('Type A'), ('Type B');
DELIMITER |
CREATE FUNCTION `EMPTY_STRING` (value TEXT)
RETURNS TEXT
DETERMINISTIC
BEGIN
RETURN IF(value IS NULL, '', value);
END|
DELIMITER ;
CREATE VIEW `myview` AS
SELECT a.*, EMPTY_STRING(b.`Name`) AS `TypeName`
FROM `mytable` a
LEFT JOIN `types` b ON a.`Type` = b.`ID`;
SELECT COUNT(*) FROM `myview` WHERE `TypeName` IS NULL;
SELECT COUNT(*) FROM `myview` WHERE `TypeName` IS NOT NULL;
SELECT COUNT(*) FROM `myview` WHERE `TypeName` LIKE '%';
(I tried to simplify my problem as far as possible.) When I run this
against MySQL 5.0.24a, I get three times "0" as output from the SELECTs
at the end -- shouldn't at least one of them match the single row?
(Preferably first and third ones.)
What am I doing wrong here? I have no clue what's going on... Thanks a
lot!
Yours,
Daniel
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