Question

In MySQL, this code works fine:

select f, blegg.* from blegg limit 1;

+------+------+------+------+
| f    | f    | g    | h    |
+------+------+------+------+
|   17 |   17 |    2 |   17 |
+------+------+------+------+
1 row in set (0.00 sec)

So why does this code cause a syntax error?

select f, * from blegg limit 1;

-- * is unqualified
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use near '* 
from blegg limit 1' at line 1

I’ve looked through the manual but didn’t really find anything. Why does select <field>, * ... fail where select <field>, <table>.* ... and select * ... and select *, <field> ... succeed?

Answer 1

The MySQL manual lays all this out pretty clearly in the section on SELECT syntax:

• A select list consisting only of a single unqualified * can be used as
  shorthand to select all columns from all tables:

  SELECT * FROM t1 INNER JOIN t2 ...
  

• tbl_name.* can be used as a
  qualified shorthand to select all columns from the named table:

  SELECT t1.*, t2.* FROM t1 INNER JOIN t2 ...
  

• Use of an unqualified *
  with other items in the select list may produce a parse error. To
  avoid this problem, use a qualified tbl_name.* reference

  SELECT AVG(score), t1.* FROM t1 ...
  

The documentation seems to indicate that * by itself is only valid in the special case where it’s the only thing in the select list. However, it only says using an unqualified * with other items may produce a parse error.

Beyond MySQL, the SQL-92 standard (old, but linkable) says as much:

7.9  <query specification>

         Format

         <query specification> ::=
              SELECT [ <set quantifier> ] <select list> <table expression>

         <select list> ::=
                <asterisk>
              | <select sublist> [ { <comma> <select sublist> }... ]

         <select sublist> ::=
                <derived column>
              | <qualifier> <period> <asterisk>

         <derived column> ::= <value expression> [ <as clause> ]

         <as clause> ::= [ AS ] <column name>

<select list> can either be <asterisk> by itself or a “normal” select list.