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    <p>Adapted this from a previous answer. This kind of stuff happens often when applications want a <em>tabbing-order</em> for variables (read: records in an EAV model) , which could also be (part of) an alternate key.</p> <ul> <li>the <code>priority</code> field needs to be kept consecutive. [this is the <em>tabbing-order</em>]</li> <li>on INSERT: all records with priority >= the new record should have their priorities incremented</li> <li>similarly: on DELETE -> decremented</li> <li>if a record's priority is altered by an UPDATE, the records between the old and the new priority value should have their priorities shifted up or down.</li> <li>to avoid recursive trigger invocation: <ul> <li>the trigger-based updates flip the <code>flipflag</code> of any record they touch. </li> <li>And they test for <code>old.flipflag=new.flipflag</code> to detect <em>real</em> updates. (those not caused by a trigger) </li> </ul></li> </ul> <hr> <pre><code> -- Make some data DROP SCHEMA tmp CASCADE; CREATE SCHEMA tmp ; SET search_path=tmp; CREATE TABLE fruits ( id INTEGER NOT NULL PRIMARY KEY , priority INTEGER NOT NULL , flipflag boolean NOT NULL default false , zname varchar NOT NULL , CONSTRAINT unique_priority UNIQUE (priority) DEFERRABLE INITIALLY DEFERRED ); INSERT INTO fruits(id,zname,priority) VALUES (1 , 'Pear' ,4) ,(2 , 'Apple' ,2) ,(3 , 'Orange' ,1) ,(4 , 'Banana' ,3) ,(5 , 'Peach' ,5) ; -- Trigger functions for Insert/update/delete CREATE function shift_priority() RETURNS TRIGGER AS $body$ BEGIN UPDATE fruits fr SET priority = priority +1 , flipflag = NOT flipflag -- alternating bit protocol ;-) WHERE NEW.priority &lt; OLD.priority AND OLD.flipflag = NEW.flipflag -- redundant condition AND fr.priority &gt;= NEW.priority AND fr.priority &lt; OLD.priority AND fr.id &lt;&gt; NEW.id -- exlude the initiating row ; UPDATE fruits fr SET priority = priority -1 , flipflag = NOT flipflag WHERE NEW.priority &gt; OLD.priority AND OLD.flipflag = NEW.flipflag AND fr.priority &lt;= NEW.priority AND fr.priority &gt; OLD.priority AND fr.id &lt;&gt; NEW.id ; RETURN NEW; END; $body$ language plpgsql; CREATE function shift_down_priority() RETURNS TRIGGER AS $body$ BEGIN UPDATE fruits fr SET priority = priority -1 , flipflag = NOT flipflag -- alternating bit protocol ;-) WHERE fr.priority &gt; OLD.priority ; RETURN NEW; END; $body$ language plpgsql; CREATE function shift_up_priority() RETURNS TRIGGER AS $body$ BEGIN UPDATE fruits fr SET priority = priority +1 , flipflag = NOT flipflag -- alternating bit protocol ;-) WHERE fr.priority &gt;= NEW.priority ; RETURN NEW; END; $body$ language plpgsql; -- Triggers for Insert/Update/Delete CREATE TRIGGER shift_priority_u AFTER UPDATE OF priority ON fruits FOR EACH ROW WHEN (OLD.flipflag = NEW.flipflag AND OLD.priority &lt;&gt; NEW.priority) EXECUTE PROCEDURE shift_priority() ; CREATE TRIGGER shift_priority_d AFTER DELETE ON fruits FOR EACH ROW EXECUTE PROCEDURE shift_down_priority() ; CREATE TRIGGER shift_priority_i BEFORE INSERT ON fruits FOR EACH ROW EXECUTE PROCEDURE shift_up_priority() ; -- Do some I/U/D operations \echo Pears are Okay UPDATE fruits SET priority = 1 WHERE id=1; -- 1,4 SELECT * FROM fruits ORDER BY priority; \echo dont want bananas DELETE FROM fruits WHERE id = 4; SELECT * FROM fruits ORDER BY priority; \echo We want Kiwis INSERT INTO fruits(id,zname,priority) VALUES (4 , 'Kiwi' ,3) ; SELECT * FROM fruits ORDER BY priority; </code></pre> <p>Result:</p> <pre><code>Pears are Okay UPDATE 1 id | priority | flipflag | zname ----+----------+----------+-------- 1 | 1 | f | Pear 3 | 2 | t | Orange 2 | 3 | t | Apple 4 | 4 | t | Banana 5 | 5 | f | Peach (5 rows) dont want bananas DELETE 1 id | priority | flipflag | zname ----+----------+----------+-------- 1 | 1 | f | Pear 3 | 2 | t | Orange 2 | 3 | t | Apple 5 | 4 | t | Peach (4 rows) We want Kiwis INSERT 0 1 id | priority | flipflag | zname ----+----------+----------+-------- 1 | 1 | f | Pear 3 | 2 | t | Orange 4 | 3 | f | Kiwi 2 | 4 | f | Apple 5 | 5 | f | Peach (5 rows) </code></pre>
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    1. POHow do I get a column with consecutive, increasing numbers, without having any numbers missing?
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    1. COAdapted from a previous answer... So this is a duplicate too?
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    2. CONo, I added code for delete and insert. The older version only had updates -->> bubbling up/down.
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    3. COYou endless-loop-prevention by alternating-bit reminds me of [this related answer](http://stackoverflow.com/a/8954058/939860), where I used deferred triggers. But I don't have the time to dive in right now.
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