MS SQL Server Join Types Panduan Lengkap untuk Menggabungkan Tabel

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 Menggabungkan tabel (join) adalah salah satu operasi dasar dalam SQL Server yang sering digunakan untuk mendapatkan data dari beberapa tabel berdasarkan relasi tertentu. Artikel ini akan membahas berbagai tipe join di SQL Server, lengkap dengan contoh dan langkah-langkah implementasi.



Inner Join

Penjelasan:

  • Mengembalikan baris yang memiliki kecocokan di kedua tabel berdasarkan kolom tertentu.

Sintaks:

SELECT kolom1, kolom2, ...

FROM tabelA

INNER JOIN tabelB

ON tabelA.kolom = tabelB.kolom;

Contoh: Kita memiliki dua tabel:


SELECT Customers.Name, Orders.Amount
FROM Customers
INNER JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;



Left Join (Outer Join)

Penjelasan:

  • Mengembalikan semua baris dari tabel kiri dan hanya baris yang cocok dari tabel kanan. Jika tidak ada kecocokan, kolom dari tabel kanan akan bernilai NULL.

Sintaks:

SELECT kolom1, kolom2, ...

FROM tabelA

LEFT JOIN tabelB

ON tabelA.kolom = tabelB.kolom;


SELECT Customers.Name, Orders.Amount
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;




Right Join (Outer Join)

Penjelasan:

  • Mengembalikan semua baris dari tabel kanan dan hanya baris yang cocok dari tabel kiri. Jika tidak ada kecocokan, kolom dari tabel kiri akan bernilai NULL.

Sintaks:

SELECT kolom1, kolom2, ...

FROM tabelA

RIGHT JOIN tabelB

ON tabelA.kolom = tabelB.kolom;



SELECT Customers.Name, Orders.Amount
FROM Customers
RIGHT JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;




Full Join (Full Outer Join)

Penjelasan:

  • Mengembalikan semua baris dari kedua tabel, dan nilai NULL jika tidak ada kecocokan.

Sintaks:

SELECT kolom1, kolom2, ...

FROM tabelA

FULL JOIN tabelB

ON tabelA.kolom = tabelB.kolom;


SELECT Customers.Name, Orders.Amount
FROM Customers
FULL JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;


Cross Join

Penjelasan:

  • Mengembalikan kombinasi kartesian dari dua tabel (setiap baris dari tabel pertama digabungkan dengan setiap baris dari tabel kedua).

Sintaks:

SELECT kolom1, kolom2, ...

FROM tabelA

CROSS JOIN tabelB;

SELECT Customers.Name, Orders.Amount
FROM Customers
CROSS JOIN Orders;

Self Join

Penjelasan:

  • Menggabungkan tabel dengan dirinya sendiri, biasanya untuk data hierarkis.

Sintaks:

SELECT A.kolom, B.kolom

FROM tabelA A

JOIN tabelA B

ON kondisi;


Contoh: Tabel Employees:



SELECT E1.Name AS Employee, E2.Name AS Manager
FROM Employees E1
LEFT JOIN Employees E2
ON E1.ManagerID = E2.EmployeeID;



Langkah-Langkah Implementasi Join

  1. Persiapkan Tabel: Pastikan tabel yang akan digabung memiliki kolom relasi.
  2. Tentukan Join yang Dibutuhkan: Pilih tipe join sesuai kebutuhan data.
  3. Tuliskan Query: Gunakan sintaks SQL yang sesuai dengan tipe join.
  4. Eksekusi Query: Jalankan query di SQL Server Management Studio (SSMS) atau tools lainnya.
  5. Verifikasi Hasil: Periksa hasil query untuk memastikan sesuai dengan yang diinginkan.
Dengan memahami berbagai tipe join di SQL Server, Anda dapat mengelola dan menganalisis data dari berbagai tabel secara lebih efektif.

Semoga bermanfaat, mohon maaf jika ada terjadi kesalahan informasi.


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