MySQL查詢當天數據最大值、最小值

系統中需要查詢到昨天數據的最大值和最小值，記錄一下

查詢當天數據最大值：

SELECT
    `c`.`gid` AS `gid`,
    `c`.`createTime` AS `createTime`,
    `c`.`creator` AS `creator`,
    `c`.`description` AS `description`,
    `c`.`editTime` AS `editTime`,
    `c`.`editor` AS `editor`,
    `c`.`isActive` AS `isActive`,
    `c`.`isDelete` AS `isDelete`,
    `c`.`current` AS `current`,
    `c`.`deviceId` AS `deviceId` 
FROM
    `current_record` `c` 
WHERE
    (
        `c`.`gid` = (
        SELECT
            max( `b`.`current` ) 
        FROM
            `current_record` `b` 
    WHERE
    (( to_days( `b`.`createTime` ) - to_days( now())) = 0 )))

 

查詢當天數據最小值：

SELECT
    `c`.`gid` AS `gid`,
    `c`.`createTime` AS `createTime`,
    `c`.`creator` AS `creator`,
    `c`.`description` AS `description`,
    `c`.`editTime` AS `editTime`,
    `c`.`editor` AS `editor`,
    `c`.`isActive` AS `isActive`,
    `c`.`isDelete` AS `isDelete`,
    `c`.`current` AS `current`,
    `c`.`deviceId` AS `deviceId` 
FROM
    `current_record` `c` 
WHERE
    (
        `c`.`gid` = (
        SELECT
            min( `b`.`current` ) 
        FROM
            `current_record` `b` 
    WHERE
    (( to_days( `b`.`createTime` ) - to_days( now())) = 0 )))

 

注意：當表里有多個最大值和最小值時，Max()和Min()函數查詢結果為空，會導致項目空指針；

解決辦法：查詢前一天時間最新的最大值數據就可以避免查詢結果為空