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Weird results with LEFT JOIN
Posted by: mysql.com_account
Date: November 29, 2004 02:11PM

I have 3 tables:

CREATE TABLE `tbl1` (
`t1c1` char(4)
);

INSERT INTO `tbl1` VALUES ('t1v1');
INSERT INTO `tbl1` VALUES ('t1v2');

CREATE TABLE `tbl2` (
`t2c1` char(4)
);

INSERT INTO `tbl2` VALUES ('t2v1');
INSERT INTO `tbl2` VALUES ('t2v2');

CREATE TABLE `tbl3` (
`t3c1` char(4),
`id` tinyint(3) unsigned NOT NULL auto_increment,
PRIMARY KEY (`id`)
);

INSERT INTO `tbl3` VALUES ('t3v1', 1);
INSERT INTO `tbl3` VALUES ('t3v2', 2);

Issuing query:

SELECT t1c1, t2c1, t3c1
FROM tbl1, tbl2
LEFT JOIN tbl3
ON tbl3.id = 1 + ROUND(RAND())

I expect total 4 rows (tbl1 x tbl2) and random values from third table in third column. But every time I get different number of rows and some values in third column are NULL. Please, can anyone explain, why is it so and how can I get expected behaviour?

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Weird results with LEFT JOIN
November 29, 2004 02:11PM


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