Self Join
Description
A self join is a join of a table to itself. This table appears twice in the
FROM
clause and is followed by table aliases that qualify column names in the join condition. (Oracle SQL Language Reference Self Join Subsection)
Sample Source Patterns
Basic Self Join case
Oracle
SELECT e1.last_name||' works for '||e2.last_name
"Employees and Their Managers"
FROM hr.employees e1, hr.employees e2
WHERE e1.manager_id = e2.employee_id
AND e1.last_name LIKE 'R%'
ORDER BY e1.last_name;
Snowflake
SELECT
NVL( e1.last_name :: STRING, '') || ' works for ' || NVL(e2.last_name :: STRING, '') "Employees and Their Managers"
FROM
hr.employees e1,
hr.employees e2
WHERE e1.manager_id = e2.employee_id
AND e1.last_name LIKE 'R%'
ORDER BY e1.last_name;
Known Issues
No issues were found.
Related EWIs
No related EWIs.
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