It may be better to use LEFT joins instead of INNER, in case some of these columns are nullable and you still want the rows returned: SELECT o.name AS object, p1.name AS parent_1, p2.name AS parent_2, c1.name AS child_1, c2.name AS child_2 FROM hierarchy_table AS h LEFT JOIN name_table AS o ON h.object_id = o.name_id LEFT JOIN name_table AS p1 ON h.parent_id_1 = p1.name_id LEFT JOIN … Click the F7 button or go under Query->Explain or click the Explain Query icon . DonationRecords.DonationAmt RIGHT JOIN can help you in finding the stream(s) for which no student has enrolled. joined; Use the ‘edit’ icon to the left for the joined column, as we’ll need to specify some extra details. To illustrate how a LEFT JOIN works, let’s simply change INNER JOIN to LEFT JOIN in our original SELECT statement, like this: SELECT Donors.DonorID,Donors.Donorname. To use the graphical explain plan feature in PgAdmin III - do the following . Launch PgAdmin III and select a database. A menu should open up. Click the SQL icon ; Type in a query or set of queries, and highlight the text of the query you want to analyse. This is my query : The query for this would be - SELECT s1.id, s1.name, s2.stream FROM student_name AS s1 RIGHT JOIN student_stream AS s2 ON s1.id = s2.id; FULL JOIN or Full Outer JOIN: FULL JOIN lets you combine both LEFT JOIN and RIGHT JOIN into a single compilation -

This makes me use the max() aggregate function and apply the result to a JOIN function on the same table as PostgreSQL does not authorize to use the columns in the SELECT clause if they do not appears in the GROUP BY clause, ALTHOUGH using a max() mean obviously I'm interested to the row containing the max values! Beispiel: Suche freie Artikelnummern unter Berücksichtigung von Lücken mittels LEFT-Join SELECT A.artnr + 1 FROM Artikel A LEFT JOIN Artikel B ON (A.artnr + 1 = B.artnr) WHERE B.artnr IS NULL Subselect SQL erlaubt die Verwendung von SELECT auch innerhalb von Ausdrücken (Subselect, Subquery, nested select).

In diesem Fall muss der SELCT-Ausdruck in runde Klammern …