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- 子查询更新数据时遇到多条数据时，可以使用SUM&MIN等函数解决：如下：
//正确的方法一对多
UPDATE `yd_draw_prize_order` SET `adopt_update_time` = (SELECT MIN(`update_time`) FROM `yd_draw_prize_order_number` WHERE `d_p_order_id` = `yd_draw_prize_order`.`d_p_order_id`) WHERE `adopt_update_time` IS NULL //报1242错误方式一对多
UPDATE `yd_draw_prize_order` SET `adopt_update_time` = (SELECT `update_time` FROM `yd_draw_prize_order_number` WHERE `d_p_order_id` = `yd_draw_prize_order`.`d_p_order_id`) WHERE `adopt_update_time` IS NULL - 时间查询 简单举例： SELECT COUNT('$column') FROM `%table` WHERE `$column` BETWEEN UNIX_TIMESTAMP('2018-05-03 00:00:01') AND UNIX_TIMESTAMP('2018-05-03 23:59:59')
更多时间查询案例；
案例分享：//FROM_UNIXTIME 将时间戳转换为字符串日期;
//UNIX_TIMESTAMP 将其他时间转换为时间戳;
SELECT
`yd_draw_prize_order`.`d_p_order_id`,
yd_draw_prize_order_log.`rand_num`,
FROM_UNIXTIME(yd_draw_prize_order.adopt_time) AS adopt_time,
FROM_UNIXTIME(
yd_draw_prize_order_log.draw_time
) AS '抽奖时间',
yd_draw_prize_order_log.`d_p_order_activity_id`,
yd_draw_prize_order_log.`d_p_order_activity_name`,
yd_draw_prize_order_log.`draw_num`,
yd_draw_prize_order_log.`winning`
FROM
`yd_draw_prize_order`
INNER JOIN `yd_draw_prize_order_number`
ON yd_draw_prize_order.d_p_order_id = yd_draw_prize_order_number.d_p_order_id
INNER JOIN `yd_draw_prize_order_log`
ON yd_draw_prize_order.d_p_order_id = yd_draw_prize_order_log.d_p_order_id
WHERE `customer_phone` = '15512816085'
AND `adopt` = 1
AND yd_draw_prize_order_number.`reward_num` = 04028
AND yd_draw_prize_order_log.draw_time > UNIX_TIMESTAMP(NOW())
AND yd_draw_prize_order_log.`d_p_order_activity_id` = 2案例2
//日期子查询;
SELECT
*
FROM
`yd_extension_data_1`
WHERE `distrbutor_id` IN
(SELECT
`distrbutor_id`
FROM
`yd_distrbutor`
WHERE `distrbutor_provinceid` = 19)
AND `create_time` BETWEEN '2017-01-01 00:00:01'
AND '2018-01-01 00:00:00'
AND `distrbutor_id` NOT IN (1,23)
ORDER BY `create_time` - 综合查询&&综合更新
综合查询案例1：1.
SELECT
b.id AS '用户id',
user_name AS '用户名',
`active_points` AS '积分',
COUNT(bet_state) AS '猜中数',
GROUP_CONCAT(bet_state) AS '统计情况',
GROUP_CONCAT(match_id) AS '赛事ID',
b.share AS '1为己分享',
`use_points` AS '消耗积分'
FROM
yd_draw_worldcup_betting AS a
INNER JOIN yd_draw_worldcup_user AS b
WHERE a.`worldcup_user_id` = b.`id`
AND a.`bet_state` IN (20, 21, 22) AND b.`use_points` <> 0
GROUP BY id; 2. SELECT
b.id AS '用户id',
user_name AS '用户名',
`active_points` AS '积分',
b.share + COUNT(bet_state) AS '自定义',
COUNT(bet_state) AS '猜中数',
b.share AS '1为己分享',
`use_points` AS '消耗积分' FROM
yd_draw_worldcup_betting AS a
INNER JOIN yd_draw_worldcup_user AS b
WHERE a.`worldcup_user_id` = b.`id`
AND a.`bet_state` IN (20, 21, 22)
AND b.`use_points` = 0
GROUP BY id;综合简单查询更新1：
1. UPDATE
`yd_draw_worldcup_user`
SET
`active_points` = `active_points` + 1
WHERE `id` IN
(SELECT
`worldcup_user_id`
FROM
`yd_draw_worldcup_betting`
WHERE `match_id` = 2
AND `bet_state` IN (20, 21, 22))综合链表更新2：
1.
update yd_draw_worldcup_user as a,yd_draw_worldcup_betting as b set
a.active_points = 0,
b.bet_state = 10,
b.draw_number = ''
where b.match_id in (1,2,3,4,5)
and b.worldcup_user_id = a.id; - 判断语句：
UPDATE yd_draw_worldcup_user AS a
SET a.active_points =
(CASE WHEN (a.active_points + a.`share` < a.use_points) THEN 0 ELSE (a.active_points + a.`share` - a.use_points) END)
WHERE 1; - 事务语句：
#mysql使用事务的关键字
#begin //打开一个事务
#commit //提交到数据库
#rollback //取消操作
#savepoint //保存，部分取消，部分提交
#alter table person type=INNODB //修改数据引擎 begin;
update tags set tagid = 133 where docid = 1;
SAVEPOINT tags1;
update tags set tagid = 530 where docid =2;
SAVEPOINT tags2;
ROLLBACK TO SAVEPOINT tags2;
SELECT * from tags where docid in(1,2);
commit; - 自定义序列号字段:
SET @rownum=0;
SELECT
@rownum:=@rownum+1 AS '序列',
a.<You_TableName_Field> AS '用户名称'
FROM
(SELECT @rownum:=0) r,<You_TableName> AS a
WHERE 1
ORDER BY <You_TableName>.<You_TableName_Field> ASC - mysql update You can't specify target table 'yd_qr_code' for update in FROM clause .
原：update `yd_qr_code` set winning_description = (select a.`winning_description` from `yd_qr_code` as a where a.`qr_id` = 1) where qr_id = 2
原理：mysql 不能在同表操作更新，我们要用一个 中间表 来让数据库认为不是同表操作；
后：update `yd_qr_code` set winning_description = (select b.`winning_description` from (select a.`winning_description` from `yd_qr_code` as a where a.`qr_id` = 1)b) where qr_id = 2 - 【查询】数据库有哪些表；
select table_schema as database_name,
table_name
from information_schema.tables
where table_type = 'BASE TABLE'
and table_name like '%__value%'
order by table_schema,
table_name;
--------------------------------
权限：
- 为用户 xuguo 添加"xu_gms" 数据库操作权限：GRANT ALL PRIVILEGES ON xu_gms.* to 'xuguo'@'%';
- 数据库文件导出： mysqldump -u username -p dbname > filename.sql
- 查看字符集：show variables like '%char%';
修改数据字符集：set character_set_database=utf8;
set character_set_server=utf8; - 修改全局变量max_allowed_packet：global max_allowed_packet = 2*1024*1024*10 ； 查看全局变量max_allowed_packet：show VARIABLES like '%max_allowed_packet%';
- --
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