Join

Description

Combines the rows from two table references based on join criteria. (Databricks SQL Language Reference JOIN)

A JOIN operation combines rows from two tables (or other table-like sources, such as views or table functions) to create a new combined row that can be used in the query. For a conceptual explanation of joins, see Working with Joins. (Snowflake SQL Language Reference JOIN)

Syntax

left_table_reference { [ join_type ] JOIN right_table_reference join_criteria |
           NATURAL join_type JOIN right_table_reference |
           CROSS JOIN right_table_reference }

join_type
  { [ INNER ] |
    LEFT [ OUTER ] |
    [ LEFT ] SEMI |
    RIGHT [ OUTER ] |
    FULL [ OUTER ] |
    [ LEFT ] ANTI |
    CROSS }

join_criteria
  { ON boolean_expression |
    USING ( column_name [, ...] ) }

Sample Source Patterns

Setup data

Databricks

-- Use employee and department tables to demonstrate different type of joins.
CREATE TEMP VIEW employee(id, name, deptno) AS
     VALUES(105, 'Chloe', 5),
           (103, 'Paul', 3),
           (101, 'John', 1),
           (102, 'Lisa', 2),
           (104, 'Evan', 4),
           (106, 'Amy', 6);

CREATE TEMP VIEW department(deptno, deptname) AS
    VALUES(3, 'Engineering'),
          (2, 'Sales'      ),
          (1, 'Marketing'  );

Snowflake

-- Use employee and department tables to demonstrate different type of joins.
CREATE TEMPORARY TABLE employee(id, name, deptno) AS
SELECT id, name, deptno
  FROM (VALUES (105, 'Chloe', 5),
           (103, 'Paul' , 3),
           (101, 'John' , 1),
           (102, 'Lisa' , 2),
           (104, 'Evan' , 4),
           (106, 'Amy'  , 6)) AS v1 (id, name, deptno);

CREATE TEMP VIEW department(deptno, deptname) AS
SELECT deptno, deptname
  FROM (VALUES(3, 'Engineering'),
          (2, 'Sales'      ),
          (1, 'Marketing'  )) AS v1 (deptno, deptname);

Pattern code

Databricks

-- 1. Use employee and department tables to demonstrate inner join.
SELECT id, name, employee.deptno, deptname
   FROM employee
   INNER JOIN department ON employee.deptno = department.deptno;
 
-- 2. Use employee and department tables to demonstrate left join.
SELECT id, name, employee.deptno, deptname
   FROM employee
   LEFT JOIN department ON employee.deptno = department.deptno;


-- 3. Use employee and department tables to demonstrate right join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    RIGHT JOIN department ON employee.deptno = department.deptno;


-- 4. Use employee and department tables to demonstrate full join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    FULL JOIN department ON employee.deptno = department.deptno;


-- 5. Use employee and department tables to demonstrate cross join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    CROSS JOIN department;

-- 6. Use employee and department tables to demonstrate semi join.
SELECT *
    FROM employee
    SEMI JOIN department ON employee.deptno = department.deptno;

Snowflake

-- 1. Use employee and department tables to demonstrate inner join.
SELECT id, name, employee.deptno, deptname
   FROM employee
   INNER JOIN department ON employee.deptno = department.deptno;
 
-- 2. Use employee and department tables to demonstrate left join.
SELECT id, name, employee.deptno, deptname
   FROM employee
   LEFT JOIN department ON employee.deptno = department.deptno;


-- 3. Use employee and department tables to demonstrate right join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    RIGHT JOIN department ON employee.deptno = department.deptno;


-- 4. Use employee and department tables to demonstrate full join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    FULL JOIN department ON employee.deptno = department.deptno;


-- 5. Use employee and department tables to demonstrate cross join.
SELECT id, name, employee.deptno, deptname
    FROM employee
    CROSS JOIN department;

-- 6. Use employee and department tables to demonstrate semi join.
SELECT e.*
    FROM employee e, department d
    WHERE e.deptno = d.deptno;

Known Issues

No issues were found

Related EWIs

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