How to join with a group by and where, including 0 values - mysql

Question

I've got some sort of static table like:
SELECT * FROM targets;
name | target
name1 | 6
name2 | 3
name3 | 2
and another table with the actual records inside, that I want to measure:
SELECT * FROM records;
id | name | created_on
546 | name1 | 2022-06-02
547 | name2 | 2022-06-04
548 | name2 | 2022-06-07
Now I'd like to build a table, that groups / counts the records per name (per month).
The group by is easy (except the 0 values):
SELECT "name", COUNT("id") FROM "records"
WHERE MONTH("created_on") = MONTH(CURRENT_DATE())
AND YEAR("created_on") = YEAR(CURRENT_DATE())
GROUP BY "name"
But how do I join both tables to get a result like this?
name | target | current
name1 | 6 | 1
name2 | 3 | 2
name3 | 3 | 0

Answer 1

your data
CREATE TABLE targets(
name VARCHAR(70) NOT NULL
,target INTEGER NOT NULL
);
INSERT INTO targets
(name,target) VALUES
('name1',6),
('name2',3),
('name3',2);
CREATE TABLE records(
id INTEGER NOT NULL
,name VARCHAR(70) NOT NULL
,created_on DATE NOT NULL
);
INSERT INTO records
(id,name,created_on) VALUES
(546,'name1','2022-06-02'),
(547,'name2','2022-06-04'),
(548,'name2','2022-06-07');
you should use Join(Left or Right) to include all values including null values and IF logical operator and Subquery to act as table for your query
SELECT targets.name,
target,
IF(current IS NULL, 0, current) AS current
FROM targets
LEFT JOIN (SELECT name,
Count(id) current
FROM records
WHERE Month(created_on) = Month(CURRENT_DATE())
AND Year(created_on) = Year(CURRENT_DATE())
GROUP BY name) records
ON records.name = targets.name
dbfiddle