mysql insert from two tables into one using inner join and max() - mysql

Question

I checked the suggested posts but couldn't find an answer. I am making a CRUD application with a many to many relationship and three MySQL tables. One table is called "pm":
CREATE TABLE `pm` (
`pm_id` int(11) NOT NULL AUTO_INCREMENT,
`pm_name` varchar(45) NOT NULL,
`pm_address` varchar(45) DEFAULT NULL,
`valid_through` int(11) NOT NULL,
PRIMARY KEY (`pm_id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8
+-------+---------+------------------------+---------------+
| pm_id | pm_name | pm_address | valid_through |
+-------+---------+------------------------+---------------+
| 1 | Alpha | http://www.alpha.com | 190303 |
| 2 | Bravo | http://www.bravo.com | 200506 |
| 3 | Charlie | http://www.charlie.com | 190708 |
| 4 | Delta | http://www.delta.com | 210509 |
| 5 | Echo | http://www.echo.com | 230416 |
| 6 | Foxtrot | http://www.foxtrot.com | 181011 |
+-------+---------+------------------------+---------------+
Another is called "searchwords":
CREATE TABLE `searchwords` (
`searchword_id` int(11) NOT NULL AUTO_INCREMENT,
`searchword` varchar(45) NOT NULL,
PRIMARY KEY (`searchword_id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8
+---------------+------------+
| searchword_id | searchword |
+---------------+------------+
| 1 | apples |
| 2 | oranges |
| 3 | pears |
| 4 | bananas |
| 5 | grapes |
+---------------+------------+
The third is join_table:
CREATE TABLE `join_table` (
`id_join_table` int(11) NOT NULL AUTO_INCREMENT,
`pm_id` int(11) DEFAULT NULL,
`searchword_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id_join_table`),
KEY `FK1_idx` (`pm_id`),
KEY `FK2_idx` (`searchword_id`),
CONSTRAINT `FK1` FOREIGN KEY (`pm_id`) REFERENCES `pm` (`pm_id`) ON DELETE
NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `FK2` FOREIGN KEY (`searchword_id`) REFERENCES `searchwords`
(`searchword_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8
+---------------+-------+---------------+
| id_join_table | pm_id | searchword_id |
+---------------+-------+---------------+
| 8 | 6 | NULL |
| 9 | 6 | NULL |
| 10 | 6 | NULL |
+---------------+-------+---------------+
Below is the SQL I have now. With for instance "oranges" at the end I want to get - into one new row of "join_table" - the max pm_id from "pm" into the pm_id column and the searchword_id that corresponds to oranges from "searchwords" into the searchword_id column.
INSERT INTO join_table (pm_id, searchword_id)
SELECT (SELECT MAX(pm_id) FROM pm), (SELECT DISTINCT
searchwords.searchword_id FROM searchwords
INNER JOIN join_table ON
searchwords.searchword_id = join_table.searchword_id
WHERE searchword = "oranges");
This SQL has magically worked sometimes but usually not (how is that kind of inconsistency even possible?). The pm_id value always gets in there so I tend to get a row with the correct value as pm_id and searchword as NULL as seen above.
Help would be much appreciated!!

Answer 1

Actually I just solved it, using:
INSERT INTO join_table (pm_id, searchword_id)
SELECT MAX(pm_id), searchword_id
FROM pm, searchwords
WHERE searchword="bananas"
Inner joins are so 2017 anyway, right?
But now I'm having problems when trying to delete a post and got an error:
Fatal error: Uncaught PDOException: SQLSTATE[23000]: Integrity constraint
violation: 1451 Cannot delete or update a parent row: a foreign key
constraint fails (`database`.`join_table`, CONSTRAINT `FK1`
FOREIGN KEY (`pm_id`) REFERENCES `pm` (`pm_id`)
Sigh