Menggabungkan tabel

Pelaporan dengan SQL

Tyler Pernes

Learning & Development Consultant

Laporan target

Medali Emas per Kelompok Demografis
(Hanya Negara Eropa Barat)
+----------+--------------------+-------+
| season   |  demographic_group | golds |
|----------+--------------------+-------|
| Winter   | Male Age 26+       | 13    |
| Winter   | Female Age 26+     | 8     |
| Summer   | Male Age 13-25     | 7     |
| Summer   | Female Age 13-25   | 6     |
| Winter   | Male Age 13-25     | 4     |
| Summer   | Male Age 26+       | 4     |
| Winter   | Female Age 13-25   | 4     |
| Summer   | Female Age 26+     | 2     |
+----------+--------------------+-------+

Tabel terkait

Opsi A: JOIN dulu, UNION kemudian

Langkah 1: Siapkan kueri atas dengan JOIN

SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM summer_games AS sg
JOIN athletes AS a 
ON sg.athlete_id = a.id;

Kueri berhasil dijalankan!

Opsi A: JOIN dulu, UNION kemudian

Langkah 2: Siapkan kueri bawah + UNION keduanya

SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM summer_games AS sg
JOIN athletes AS a 
ON sg.athlete_id = a.id
UNION ALL
SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM winter_games AS wg
JOIN athletes AS a 
ON wg.athlete_id = a.id;

Opsi B: UNION dulu, JOIN kemudian

Langkah 1: Buat UNION awal

SELECT 
    athlete_id, 
    gold  
FROM summer_games AS sg
UNION
SELECT 
    athlete_id, 
    gold  
FROM winter_games AS wg;

Opsi B: UNION dulu, JOIN kemudian

Langkah 2: Ubah jadi subkueri + JOIN

SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM
    (SELECT 
         athlete_id, 
         gold  
    FROM summer_games AS sg
    UNION ALL
    SELECT athlete_id, gold  
    FROM winter_games AS wg) AS g
JOIN athletes AS a 
ON g.athlete_id = a.id;

Perbandingan

Opsi A

SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM summer_games AS sg
JOIN athletes AS a 
ON sg.athlete_id = a.id
UNION ALL
SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM winter_games AS wg
JOIN athletes AS a 
ON wg.athlete_id = a.id;

Opsi B

SELECT 
    athlete_id, 
    gender, 
    age, 
    gold  
FROM
    (SELECT 
         athlete_id, 
         gold  
    FROM summer_games AS sg
    UNION ALL
    SELECT athlete_id, gold  
    FROM winter_games AS wg) AS g
JOIN athletes AS a 
ON g.athlete_id = a.id;

Inti pembelajaran

Ada beberapa cara untuk membuat laporan yang sama
Langkah demi langkah = lebih mudah ditelusuri

Saatnya kueri!

Pelaporan dengan SQL