Grouping AND and OR conditionals in PostgreSQL

Question

I always use brackets in sql queries. But I have example:

DELETE FROM prog 
WHERE prog_start >= $1 AND prog_start < $2
   OR prog_end > $1 AND prog_end <= $2

Is it equal to :

DELETE FROM prog
WHERE ( prog_start >= $1 AND prog_start < $2 )
   OR ( prog_end > $1 AND prog_end <= $2 )

or not ?

score 37 · Accepted Answer · edited Jun 22 '18 at 08:48

37

In SQL the AND operator takes "precedence" over OR operator. PostgreSQL adheres to the spec here. You can the exact precedence in PostgreSQL in the docs Lexical Structure: Operator Precedence.

So in your case, the result will be the same. However, it's much easier, and cleaner to simply use the parentheses.

edited Jun 22 '18 at 08:48

Evan Carroll

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answered Apr 26 '12 at 10:33

Raphaël Althaus

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Rahul · Answer 2 · 2012-04-26T11:03:30.483

1

It goes as per the Operator Precendence http://www.postgresql.org/docs/6.5/static/operators.htm#AEN1615.

To form a complex condition it's always better to parenthesis your conditions.

edited Apr 26 '12 at 11:03

answered Apr 26 '12 at 10:40

Rahul

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good analysis, but... wrong conclusion on this particular case, no ? – Raphaël Althaus Apr 26 '12 at 10:49
2

6.5 is a bit outdated version to reference. – vyegorov Apr 26 '12 at 10:54
1

http://www.postgresql.org/docs/9.0/static/sql-syntax-lexical.html#SQL-SYNTAX-OPERATORS (or /and operators precedence changes are probably not the most usual changes, by the way...) – Raphaël Althaus Apr 26 '12 at 10:57
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About referencing the PostgreSQL manual, consider http://meta.stackexchange.com/questions/108714/best-way-to-reference-the-postgresql-manual – Erwin Brandstetter Apr 26 '12 at 15:39
Proper link to current manual: http://www.postgresql.org/docs/current/interactive/sql-syntax-lexical.html#SQL-SYNTAX-OPERATORS – Erwin Brandstetter Nov 05 '12 at 04:19

Grouping AND and OR conditionals in PostgreSQL

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