Keith Medcalf wrote:
> If you do not provide as AS clause to give a result column a name, then
> each implementation is free to provide whatever names it feels like (so
> sayeth the standard).
The SQL-92 standard actually says:
| 6.4 <column reference>
|
| <column reference> ::= [ <qualifier> <period> ] <column name>
|
| 7.9 <query specification>
|
| <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>
|
| Syntax Rules
|
| 9) Case:
|
| a) If the i-th <derived column> in the <select list> specifies
| an <as clause> that contains a <column name> C, then the
| <column name> of the i-th column of the result is C.
|
| b) If the i-th <derived column> in the <select list> does not
| specify an <as clause> and the <value expression> of that
| <derived column> is a single <column reference>, then the
| <column name> of the i-th column of the result is C.
|
| c) Otherwise, the <column name> of the i-th column of the <query
| specification> is implementation-dependent and different
| from the <column name> of any column, other than itself, of
| a table referenced by any <table reference> contained in the
| SQL-statement.
SQLite's default short_column_names setting implements rule b).
Regards,
Clemens
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