存儲過程事例

BEGIN
    -- 定義變量
    DECLARE s int DEFAULT 0;
    DECLARE isE tinyint(1) DEFAULT 0;
    DECLARE vehicleId char(32); -- 車輛id
    DECLARE num decimal(5,2); -- 加油數量 單位升
    DECLARE oilWear decimal(5,2); -- 百千米油耗
    DECLARE mileage decimal(8,2) DEFAULT(0); -- 區間內的千米數
    DECLARE beginTime datetime;    -- 上上次加油時間 
    DECLARE endTime datetime; -- 上次加油時間
    DECLARE addNum int DEFAULT 0; -- 添加條數
    -- 定義遊標，並將sql結果集賦值到遊標中
    DECLARE report CURSOR FOR select r.create_time as begin_time,r2.create_time as end_time,r.num,r.vehicle_id from mjm_refuel_record as r
        JOIN(
        select vehicle_id,create_time FROM mjm_refuel_record 
        where TO_DAYS(NOW( )) - to_days(create_time) =1
        GROUP BY vehicle_id
        ORDER BY create_time DESC
        ) as r2 on r.vehicle_id = r2.vehicle_id and r.create_time < r2.create_time
        GROUP BY r.vehicle_id
        ORDER BY r.create_time desc;
    -- 聲明當遊標遍歷完後將標誌變量置成某個值
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET s=1;
    -- 打開遊標
    open report;
        -- 將遊標中的值賦值給變量，注意：變量名不要和返回的列名同名，變量順序要和sql結果列的順序一致
        fetch report into beginTime,endTime,num,vehicleId;
        -- 當s不等於1，也就是未遍歷完時，會一直循環
        while s<>1 do
        -- 執行業務邏輯
            SELECT IFNULL(sum(today_mileage/10),0) into mileage from mjm_gps_record_collect WHERE vehicle_id = vehicleId and  update_time>= beginTime and update_time <=endTime; 
        -- 是否存在記錄
            SELECT count(1) into isE from mjm_oil_wear_collect WHERE vehicle_id = vehicleId AND day = DATE(NOW());
            IF mileage>0 THEN
                set oilWear = num*(100/mileage);
                IF isE THEN
                    UPDATE mjm_oil_wear_collect SET oil_num = oilWear,oil_num = num,mileage = mileage,begin_time=beginTime,end_time=endTime WHERE vehicle_id = vehicleId AND day = DATE(NOW());
                ELSE
                    INSERT into mjm_oil_wear_collect(id,vehicle_id,day,oil_wear,oil_num,mileage,begin_time,end_time) VALUES(replace(UUID(),'-',''),vehicleId, DATE(NOW()),oilWear,num,mileage,beginTime,endTime);
                END IF;
                set addNum = addNum+1;
            END IF;
            -- 將遊標中的值再賦值給變量，供下次循環使用
            fetch report into beginTime,endTime,num,vehicleId;
        -- 當s等於1時代表遍歷以完成，退出循環
        end while;
    -- 關閉遊標
    close report;
    RETURN addNum;
END

該事例爲統計百千米車輛油耗作的存儲過程，而後後臺作定時任務。根據加油的時間範圍獲取車輛的里程，再根據里程與油耗算出上次的百千米油耗。