SQL · Theory

Right Join

Theory

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Right Join

RIGHT JOIN keeps all rows from the right table. It is LEFT JOIN with the tables swapped. Most teams write LEFT JOIN only, and put the ‘must keep’ table on the left.

Know the name for MCQs. In code, prefer LEFT JOIN for readability.

Trap — mixing LEFT and RIGHT in one query until nobody can draw it.

On the example next to this theory — Right Join — jOIN combines rows using a match condition between tables.

Diagram

  students.id
       =
  marks.student_id
        │
        ▼
     one result row

Exam tip

RIGHT JOIN = LEFT JOIN with tables swapped. Prefer LEFT.

Right Join — sample query

CREATE TABLE customers (id INTEGER PRIMARY KEY, name TEXT);
CREATE TABLE orders (id INTEGER PRIMARY KEY, customer_id INTEGER, total INTEGER);
INSERT INTO customers VALUES (1, 'Asha'), (2, 'Ravi');
INSERT INTO orders VALUES (10, 1, 500), (11, 1, 200);
SELECT c.name, o.total
FROM customers c
JOIN orders o ON o.customer_id = c.id;

Right Join — jOIN combines rows using a match condition between tables.

Short notes

DefRIGHT JOIN keeps all right-table rows.
RuleSame as swapping tables and using LEFT JOIN.
TrapUsing RIGHT when LEFT would read better.

CREATE TABLE customers (id INTEGER PRIMARY KEY, name TEXT); CREATE TABLE orders (id INTEGER PRIMARY KEY, customer_id INTEGER, total INTEGER); INSERT INTO customers VALUES (1, 'Asha'), (2, 'Ravi'); INSERT INTO orders VALUES (10, 1, 500), (11, 1, 200); SELECT c.name, o.total FROM customers c JOIN orders o ON o.customer_id = c.id;

Right Join

Right Join — sample query

Short notes

Questions

Right Join

Right Join — sample query

Short notes

Questions