SQL Queries

MySQL keywords are always capitalized: SELECT, INSERT, UPDATE, WHERE, AS, JOIN, ON, IN, etc.
Break up long queries into multiple lines for legibility, preferably breaking for each clause.

INCORRECT: 

// keywords are lowercase and query is too long for 

// a single line (... indicates continuation of line) 

$query = $this->db->query("select foo, bar, baz, foofoo, foobar as raboof, foobaz from exp_pre_email_addresses 

...where foo != 'oof' and baz != 'zab' order by foobaz limit 5, 100");

 

CORRECT: 

$query = $this->db->query("SELECT foo, bar, baz, foofoo, foobar AS raboof, foobaz FROM exp_pre_email_addresses 

WHERE foo != 'oof' 

AND baz != 'zab' 

ORDER BY foobaz 

LIMIT 5, 100");