+--------------------+---------------+------+-----+---------+-------+
| ID | GKEY |GOODS | PRI | COUNTRY | Extra |
+--------------------+---------------+------+-----+---------+-------+
| 1 | BOOK-1 | 1 | 10 | | |
| 2 | PHONE-1 | 2 | 12 | | |
| 3 | BOOK-2 | 1 | 13 | | |
| 4 | BOOK-3 | 1 | 10 | | |
| 5 | PHONE-2 | 2 | 10 | | |
| 6 | PHONE-3 | 2 | 20 | | |
| 7 | BOOK-10 | 2 | 20 | | |
| 8 | BOOK-11 | 2 | 20 | | |
| 9 | BOOK-20 | 2 | 20 | | |
| 10 | BOOK-21 | 2 | 20 | | |
| 11 | PHONE-30 | 2 | 20 | | |
+--------------------+---------------+------+-----+---------+-------+
Above is my table. I want to get all records which GKEY > BOOK-2, Who can tell me the expression with mysql?
Using " 开发者_如何学编程WHERE GKEY>'BOOK-2' " Cannot get the correct results.
How about (something like):
(this is MSSQL - I guess it will be similar in MySQL)
select
*
from
(
select
*,
index = convert(int,replace(GKEY,'BOOK-',''))
from table
where
GKEY like 'BOOK%'
) sub
where
sub.index > 2
By way of explanation: The inner query basically recreates your table, but only for BOOK rows, and with an extra column containing the index in the right data type to make a greater than comparison work numerically.
Alternatively something like this:
select
*
from table
where
(
case
when GKEY like 'BOOK%' then
case when convert(int,replace(GKEY,'BOOK-','')) > 2 then 1
else 0
end
else 0
end
) = 1
Essentially the problem is that you need to check for BOOK before you turn the index into a numberic, as the other values of GKEY would create an error (without doing some clunky string handling).
SELECT * FROM `table` AS `t1` WHERE `t1`.`id` > (SELECT `id` FROM `table` AS `t2` WHERE `t2`.`GKEY`='BOOK-2' LIMIT 1)
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