Always use type that fit your needs, as this will optimize memory usage and lead to better performance

1. Model,
2. Repository (berhubungan dgn Db / Microservices),
3. Service (Business Logic)
4. Controller (isinya crud si gin)

go test ./... -v -coverprofile cover.out; go tool cover -html cover.out

• WaitGroup purpose is to wait until goroutines finished executing before the program end

• Mutex purpose is to ensure only one goroutine accesses data at a time. Basically, is to prevent changing data at the same time

• Mutex.RLock & Mutex.RUnlock. if Mutex is currently locked by Mutex.Lock then Mutex.RLock will wait till its released. Basically, to prevent reading wrong data when Mutex.Lock working on changing some data

• Channel should be closed if it's not being used, because it will cause memory leak

SELECT column_name, COUNT(*) FROM table_name WHERE condition GROUP BY column_name;
Example: SELECT major, COUNT(*) AS jumlah_peserta FROM mst_student WHERE major LIKE 'S%' GROUP BY major ;
Output:

ALTER TABLE table_name ADD CONSTRAINT constraint_name FOREIGN KEY(column_name) REFERENCES table_name_sec(column_name_sec)
Example: ALTER TABLE mst_product ADD CONSTRAINT fk_product_store FOREIGN KEY(store_id) REFERENCES mst_store(id)

-) Learn Database Normalization
https://youtu.be/GFQaEYEc8_8?si=-3F8fcKEYroFU9YE
https://youtu.be/UC_tJx4MBgk?si=Aa9aXHRZWpGfrgvZ