MySQL：UPDATing没有保证唯一字段的行

Question

I am working with an old MySQL table, which serves as a log of sorts. It looks like

CREATE TABLE `queries` (
  `Email` char(32) NOT NULL DEFAULT '',
  `Query` blob,
  `NumRecords` int(5) unsigned DEFAULT NULL,
  `Date` date DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

Now, I need to be able to UPDATE the records in this table (don't ask why, I don't know). Normally, I would just do

UPDATE table SET ... WHERE unique_column = value

But in this case, I don't have a unique column to work from.

Is there a workaround for this, or am I just going to have to push to put in a nice, standard INT NOT NULL AUTO_INCREMENT?

Answer 1

UPDATE queries 
SET ... 
WHERE Email = value1 
  AND Query = value2 
  AND NumRecords = value3 
  AND Date = value4 
LIMIT 1;