RE: Finding gaps

[US Data Export]

>-----Original Message-----
>From: Gerald L. Clark [mailto:gerald_clark@stripped]
>Sent: Wednesday, October 08, 2008 4:44 PM
>To: Jerry Schwartz
>Cc: mysql@stripped
>Subject: Re: Finding gaps
>
>Jerry Schwartz wrote:
>> I'm finally getting back to this issue, and I've read the bits on
>> artfulsoftware. The example
>>
>> SELECT
>>   a.id+1 AS 'Missing From',
>>   MIN(b.id) - 1 AS 'To'
>> FROM tbl AS a, tbl AS b
>> WHERE a.id < b.id
>> GROUP BY a.id
>> HAVING a.id < MIN(b.id) - 1;
>>
>SELECT
>    a.id+1 AS `Missing_From`,
>    MIN(b.id) - 1 AS `To`
>FROM tbl AS a, tbl AS b
>WHERE a.id < b.id
>GROUP BY a.id
>HAVING a.id < `To`
[JS] That didn't seem to work:

mysql> SELECT a.prod_num + 1 AS `Missing From`,
    ->   MIN(b.prod_num) - 1 AS `To`
    -> FROM prod AS a, prod AS b
    -> WHERE a.prod_num < b.prod_num
    -> GROUP BY a.prod_num
    -> HAVING a.prod_num < `To`;
ERROR 1054 (42S22): Unknown column 'a.prod_num' in 'having clause'