利用Mysql定时+存储过程创建临时表统计数据的过程

show variables like '%event_sche%';

--开启定时调度策略（下面两个语句都可以）
set global event_scheduler=1;
set global event_scheduler = on;
 
--关闭定时调度策略（下面两个语句都可以）
set global event_scheduler=0;
set global event_scheduler = off;

# 用户信息表
CREATE TABLE `user_info` (
    `id` INT ( 11 ) NOT NULL AUTO_INCREMENT COMMENT 'ID',
    `name` VARCHAR ( 30 ) NOT NULL COMMENT '用户名',
    `phone` VARCHAR ( 11 ) NOT NULL COMMENT '手机号',
    `status` TINYINT ( 1 ) NULL DEFAULT NULL COMMENT '用户状态:停用0，启动1',
    `create_time` datetime NOT NULL COMMENT '创建时间',
    PRIMARY KEY ( `id` ) USING BTREE 
) ENGINE = INNODB AUTO_INCREMENT = 10001 CHARACTER 
SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '用户信息表';
 
# 用户订单表
CREATE TABLE `user_order`  (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
  `order_num` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '订单编号',
  `user_id` int(11) NOT NULL COMMENT '用户ID',
  `create_time` datetime NOT NULL COMMENT '创建时间',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `idx_order_num`(`order_num`) USING BTREE COMMENT '订单编号唯一'
) ENGINE = INNODB AUTO_INCREMENT = 10001 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '用户订单表';

# 向用户信息表中插入三条测试数据
INSERT INTO `user_info` (`id`, `name`, `phone`, `status`, `create_time`) VALUES (10001, '张三', '13900669010', 1, '2023-03-14 17:01:42');
INSERT INTO  `user_info` (`id`, `name`, `phone`, `status`, `create_time`) VALUES (10002, '李四', '13900669111', 1, '2023-03-14 17:01:42');
INSERT INTO  `user_info` (`id`, `name`, `phone`, `status`, `create_time`) VALUES (10003, '王五', '13900669876', 1, '2023-03-14 17:01:42');
 
# 向用户订单表中插入八条测试数据
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10001, 'dingdan001', 10002, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10002, 'dingdan002', 10003, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10003, 'dingdan003', 10002, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10004, 'dingdan004', 10002, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10005, 'dingdan005', 10003, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10006, 'dingdan006', 10003, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10007, 'dingdan007', 10002, '2023-03-14 17:03:40');
INSERT INTO  `user_order` (`id`, `order_num`, `user_id`, `create_time`) VALUES (10008, 'dingdan008', 10001, '2023-03-14 17:03:40');

 
DELIMITER //
DROP PROCEDURE
IF
    EXISTS statistics_user_order // CREATE PROCEDURE statistics_user_order () BEGIN
    DECLARE
        temp_table_name VARCHAR ( 60 ) DEFAULT '';
    DECLARE
        suffix VARCHAR ( 10 ) DEFAULT '';
    DECLARE
        old_table_name VARCHAR ( 60 ) DEFAULT NULL;
    SELECT
        table_name INTO old_table_name 
    FROM
        information_schema.`TABLES` 
    WHERE
        table_name LIKE 'temp_statistics_%' 
        AND table_schema = 'db_name'; -- 此处填自己对应的数据库名即可
    IF
        old_table_name IS NOT NULL THEN
        -- execute multiple statements
        -- 如果IF THEN ... END IF块内有多个语句,最好将它们放在一个BEGIN ... END;块中
        BEGIN
                
                SET @drop_sql := CONCAT( 'DROP TABLE ', old_table_name, ';' );
            PREPARE d_sql 
            FROM
                @drop_sql;
            EXECUTE d_sql;
            DEALLOCATE PREPARE d_sql;
            
        END;
        
    END IF;
    SELECT
        DATE_FORMAT( NOW(), '%Y%m%d' ) INTO suffix;
    
    SET temp_table_name = CONCAT( 'temp_statistics_', suffix );
    
    SET @create_sql = CONCAT( 'create table if not exists ', temp_table_name, "(
        `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
        `user_id` INT ( 11 ) NOT NULL COMMENT '用户ID',
        `name` VARCHAR ( 30 ) NOT NULL COMMENT '用户名',
        `number` INT ( 11 ) NOT NULL DEFAULT 0 COMMENT '订单数',
        `create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
        PRIMARY KEY ( `id` ) USING BTREE 
    ) ENGINE = INNODB AUTO_INCREMENT = 1 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '用户订单统计表';" );
    PREPARE pre_stmt 
    FROM
        @create_sql;
    EXECUTE pre_stmt;
    DEALLOCATE PREPARE pre_stmt;
    -- 简单的用set或者declare语句定义变量，然后直接作为sql的表名是不行的，mysql会把变量名当作表名。
    SET @insert_sql = CONCAT( 'INSERT INTO ', temp_table_name, "( `user_id`, `name`, `number` ) SELECT
        i.id AS `user_id`,
        i.`name` AS `name`,
        COUNT( o.user_id ) AS `number` 
        FROM
        user_info i
        LEFT JOIN user_order o ON i.id = o.user_id 
        WHERE
        i.`status` = 1 
        GROUP BY
    i.id;" );
    PREPARE pre_insert 
    FROM
        @insert_sql;
    EXECUTE pre_insert;
    DEALLOCATE PREPARE pre_insert;
    
END // 
DELIMITER;

create event job_statistics -- 是创建名为job_statistics的事件；
on schedule every 10 SECOND -- 创建周期定时的规则，意思是每10s种执行一次；
on completion preserve enable --  是表示创建后就开始生效，不让开始生效设置disable
do call statistics_user_order(); -- 事件要执行的内容，调用了上述的存储过程

select * from information_schema.EVENTS;

ALTER event job_statistics on completion preserve disable;

ALTER event job_statistics on completion preserve enable;