Re: MySQL/PostgreSQL discrepancy - Thimble Smith - com.mysql.lists.bugs

3 messages in com.mysql.lists.bugsRe: MySQL/PostgreSQL discrepancy

From	Sent On	Attachments
Thimble Smith	02 Nov 2000 13:00
Benjamin Pflugmann	03 Nov 2000 14:24
Michael Widenius	04 Nov 2000 08:58

Subject:	Re: MySQL/PostgreSQL discrepancy
From:	Thimble Smith (ti...@mysql.com)
Date:	11/02/2000 01:00:19 PM
List:	com.mysql.lists.bugs

On Wed, Nov 01, 2000 at 12:51:42PM +0900, Ken Smith wrote:

I sent the following message to the PostgreSQL mailing list and got three responses. Each one points to the same point in the standard which contradicts behavior I have seen when using MySQL. Please let me know if you disagree with their assertions. I am not subscribed to this list so please cc my personal email address in your correspondence.

Yes, it looks like MySQL does the wrong thing here. It's a bug that we'll need to fix. I expect it won't be fixed in 3.23, but I could be wrong.

Thanks for pointing it out!

Tim

---The original email BEGIN---

THE TEST Run 'psql', then enter the following except for the select statement output.

---BEGIN--- create table test (name char, a int, b int); insert into test values ('x', 1, 2); select * from test; update test set a=3,b=a where name='x'; insert into test values ('y', 1, 2); update test set b=a,a=3 where name='y'; select * from test; name | a | b ------+---+--- x | 3 | 1 y | 3 | 1 drop table test; ---END---

I am used to MySQL so I expected the following from the select statement. name | a | b ------+---+--- x | 3 | 3 y | 3 | 1

Which behavior is the correct?

---The original email END---

---The responses BEGIN--- I believe ours...

From update positioned:

"The <value expression>s are effecitvely evaluated before updating the object row. If a <value expression> contains a reference to a column of T, then the reference is to the value of that column in the object row before any value of the object row is updated."

From update searched:

"The <value expressions> are effectively evaluated for each row of T before updating any row of T."