Thanx for the fast answer. I already thought something about like this and considered sending the question to the advocacy list instead of the SQL list. I really like their docs since i´ve read about their reasons against Foreign Keys *g*
One more point in favor for PostgreSQL :) Christoph Nelles Am Freitag, 4. Juli 2003 um 23:45 schrieben Sie: TL> Evil Azrael <[EMAIL PROTECTED]> writes: >> I have a problem with this part in the text >> ---- >> The target table of the INSERT statement cannot appear in the FROM >> clause of the SELECT part of the query because it's forbidden in >> standard SQL to SELECT from the same table into which you are >> inserting. TL> This is just MySQL's self-serving reading of the spec. What SQL92 TL> actually says is (section 13.8) TL> 1) The following restrictions apply for Intermediate SQL: TL> a) The leaf generally underlying table of T shall not be gen- TL> erally contained in the <query expression> immediately TL> contained in the <insert columns and source> except as the TL> <qualifier> of a <column reference>. TL> SQL99 puts it a little differently: TL> Conformance Rules TL> 1) Without Feature F781, "Self-referencing operations", no leaf TL> generally underlying table of T shall be generally contained in TL> the <query expression> immediately contained in the <insert TL> columns and source> except as the <table or query name> or TL> <correlation name> of a column reference. TL> In other words, the behavior is perfectly standard, it's just not TL> required for minimal SQL implementations to support it. TL> What the standard behavior is is defined by this rule, earlier in the TL> same section: TL> 3) The <query expression> is effectively evaluated before inserting TL> any rows into B. TL> that is, the SELECT doesn't see any rows that are being inserted into TL> the target table during the same command. There would not be any need TL> for that rule if selecting from the same table you're inserting into TL> were flat-out forbidden, as the MySQL docs claim. TL> regards, tom lane -- Mit freundlichen Grüssen Evil Azrael mailto:[EMAIL PROTECTED] ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
