mysql - SQL 查询从表中检索下一个可用 ID

Question

我有一个表，其中包含一个名为 ticket_id 的列，它包含如下值:

ticket_id
STK0000000001
STK0000000002
STK0000000001
STK0000000003
STK0000000002
STK0000000001

ticket_id 值会在某些行中重复，因此它不是唯一的。

我正在使用此查询获取下一个可用 ID，但我无法使其正常工作。它始终返回 STK0000000002。

感谢任何帮助!

SQL:

SELECT
    CONCAT('STK', LPAD(seq, 10, '0')) AS nextID
FROM
    (SELECT
        @seq:=@seq+1 AS seq,
        num
    FROM
        (SELECT
            CAST(SUBSTR(ticket_id, 4) AS UNSIGNED) AS num
        FROM
            sma_support_tickets
        UNION ALL
        SELECT
            MAX(CAST(SUBSTR(ticket_id, 4) AS UNSIGNED))+2 AS num
        FROM 
            sma_support_tickets
        ORDER BY
            num) AS ids
    CROSS JOIN 
        (SELECT @seq:=0) AS init 
    ) AS pairs
WHERE
    seq!=num
LIMIT 1

Answer 1

也许我在你的问题中遗漏了一些东西，但似乎应该这样做:

SELECT CONCAT('STK', 
              LPAD(MAX(SUBSTRING(ticket_id, 4)) + 1, 
                   10, 
                   '0')
             ) 
FROM sma_support_tickets;