Question

I have a query submitting multiple items in table a.

For example:

insert into a values(id,name) (5,'john'),(6,'smith');

Though I also need to select some third value from other table with this id.

For example:

insert into a values(id,name,money) (5,'john',(select money from b where id=5)),(6,'smith',(select money from b where id=6));

The problem with the above is that it’s a bit repetitive and also uses sub selects.

I wonder if it’s possible to rewrite this using JOIN, (which should also reassure that there is a relation to the table b on that given id, lest it inserts a NULL).

Any ideas?

Answer 1

You’re allowed only one SELECT for each INSERT so you need to re-write this to select multiple rows, not insert multiple values at once. Could you create a temporary table with the two sets of values in it and INSERT those with a JOIN?

CREATE TEMPORARY TABLE _tmp_a (id INT PRIMARY KEY, name VARCHAR(255));
INSERT INTO _tmp_a (5, 'john'), (6, 'smith')
INSERT INTO a (id, name, money) SELECT _tmp_a.id, _tmp_a.name, b.money FROM _tmp_a LEFT JOIN b ON b.id=_tmp_a.id