INSERTing values into a child table referenced from parent table - mysql

Question

I was up all last night trying to crack this but with no luck so I'm hoping you guys can help as I'm all out of ideas:
I have two parent tables that I want to populate a Junction table from:
Brides:
create table if not exists `Brides` (
`BrideID` INT not null auto_increment,
`MaidenName` varchar(10) unique,
primary key (`BrideID`)
) engine=InnoDB;
insert into Brides (MaidenName)
values ('Smith'),
('Jones')
;
Churches:
create table if not exists `Churches` (
`ChurchID` INT not null auto_increment,
`ChurchName` varchar(10) unique,
primary key (`ChurchID`)
) engine=InnoDB;
insert into Churches (ChurchName)
values ('St Marys'),
('St Albans')
;
I am trying to populate the ID variables for Junction table Marriages by indirectly referencing the unique names in each parent table. In addition, I'm looking to include MarriedName to identify if a Bride marries more than once:
Marriages:
create table if not exists 'Marriages' (
'BrideID' INT not null,
'ChurchID' INT not null,
'MarriedName' TEXT not null
primary key ('BrideID','ChurchID','MarriedName')
INDEX `fk_Marriages_Brides1_idx` (`BrideID` ASC),
INDEX `fk_Marriages_Churches1_idx` (`ChurchID` ASC),
CONSTRAINT `fk_Marriages_Brides1`
FOREIGN KEY (`BrideID`)
REFERENCES `Brides` (`BrideID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_Marriages_Churches1`
FOREIGN KEY (`Church_ID`)
REFERENCES `Churches` (`ChurchID`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
;
I'm trying to do something like the below pseudo-code (although I'm pretty sure it wouldn't be the smart way to do it anyway as must be slow with with so many sub-queries):
insert into Marriages (Bride_ID, Church_ID, MarriedName)
select b.BrideID, c.ChurchID, m.MarriedName
from (values (Bride,Church,MarriedName)
('Smith','St Marys','Johnson'),
('Jones','St Albans','Peterson')
) m
join Brides b
on a.MaidenName=m.Bride
join Churches c
on m.Church=c.ChurchName;
Any help/insight/corrections you have would be greatly appreciated!

Answer 1

Give this a try:
INSERT INTO Marriages
SELECT b.BrideID, c.ChurchID, 'Johnson'
FROM Brides b, Churches c
WHERE b.MaidenName='Smith' AND c.ChurchName='St Marys'

Answer 2

Just for completeness, I wanted to share this solution in case it helps anyone else....First and last step requires no changes and just the 'raw' data in the second step needs adding to:
create table if not exists `_marriages` (
`BrideName` varchar(10) null,
`ChurchName` varchar(10) null,
`MarriedName` varchar(10) NULL,
primary key (`BrideName`,`ChurchName`,`MarriedName`))
engine=InnoDB
;
insert into `_marriages` (BrideName,ChurchName,MarriedName)
values
('Smith','St Albans','Johnson'),
('Jones','St Marys','Peterson')
;
insert into `Marriages` (Bride_ID, Church_ID, MarriedName)
select distinct b.BrideID, c.ChurchID, a.MarriedName
from _marriages a
inner join Brides b
on (a.BrideName=b.MaidenName)
left join Churches c
on a.ChurchName=c.ChurchName
;
...as always though, if anyone has any advancement on a better way to do it please let us know!