The four common clauses are WHERE, GROUP BY, ORDER BY, and LIMIT (LIMIT is an extension to the SQL standard). Examples:
You can also, and frequently will, use multiple clauses in the same query. The clauses always go in this order:
SELECT columns FROM tablename WHERE clause GROUP BY columnname ORDER BY columnname LIMIT x
Clauses can be applied just to a column name, or they can be used in conjunction with parentheses and operators to create more elaborate conditionals. Table B.3 lists the operators and comparators you'll commonly use.