Sql by Marcos Benevides

:ID: 11f7d9cc-51a6-4897-955b-37a756105677 :EXPORT_HUGO_CATEGORIES: “Databases” :EXPORT_HUGO_TAGS: “SQL”

Logical Query Processing Order

FROM

JOIN

Step Description
1 Cartesian product
2 Qualification step (i.e. the ON filter)
3 LEFT or RIGHT reservations

If the specified JOIN type is a CROSS JOIN, then the query planner stops at Step 1 and return the cartesian product to the next clause. All other join types proceed to the qualification step.

INNER and OUTER JOINS are called “qualified JOINs”, the qualification predicated is specified using the ON keyword, which filters all rows from the previous cartesian step where the predicate is TRUE. If the request is an INNER JOIN, then the qualified rows are returned to the next clause, if it is an OUTER JOIN, the qualified rows go throught the next step.

WHERE

GROUP BY

HAVING

SELECT

ORDER BY

OFFSET/FETCH

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