Obtain value preceding maximum value

For example, gi开发者_开发问答ven this table of sparse ids:

|id|
| 1|
| 2|
| 3|
| 6|
| 7|

I can obtain the highest "id" from my table using this query:

SELECT max(id) FROM Comics

I get:

|id|
| 7|

How can I get the "id" just preceding the highest "id" (even if the values aren't continuous)?

In general terms, you could first find the maximum id (which you've done), then find the maximum id that is less than (<) the maximum.

Specifically,

select max(id) from Comics where id < 7

Alternately, you can order the results in descending order:

select id from Comics order by id desc

and then look at the second row returned.

SELECT max(id) FROM Comics

is the same as

SELECT TOP 1 id FROM Comics ORDER BY ID DESC

note: this is transact sql syntax, use rownum or limit depending on your vendor

to get row 2 you can do

SELECT TOP 1 ID 
FROM 
    (SELECT TOP 2 id 
     FROM Comics 
     ORDER BY ID DESC) 
ORDER BY ID ASC

this would do it as well ..

SELECT
    max(id)
FROM
    Comics 
WHERE id < (SELECT max(id) FROM Comics)