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ââ1ï¼ä¸æ¡SQLè¯å¥æ¥è¯¢åºæææ绩大äº80çå¦çå§åââ
ââ建表è¯å¥ââ
ââ解é¢æè·¯ââ
ââ2ï¼æ¥è¯¢åä¸å¤© temperature æ¯åä¸å¤©é«çdateââ
ââ建表è¯å¥ââ
ââ解é¢æè·¯ââ
ââ3ï¼æ¥è¯¢æ¯ä¸ªä¸»æçæ大level以å对åºçæå°gap(注æ:ä¸æ¯æ¯ä¸ªä¸»æçæ大levelåæå°gap)ââ
ââ建表è¯å¥ââ
ââ解é¢æè·¯ââ
ââ4ï¼è¯¾ç¨æ°æ®è¡è½¬åââ
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ââ解é¢æè·¯ââ
ââ5ï¼æ两个表AåBï¼åækeyåvalue两个å段ï¼å¦æBçkeyå¨Aä¸ä¹æï¼å°±æBçvalueæ¢ä¸ºAä¸å¯¹åºçvalueââ
ââ建表è¯å¥ââ
ââ解é¢æè·¯ââ
ââ6ï¼è®¾è®¡è¡¨ï¼å ³ç³»å¦ä¸ï¼æå¸ãç级ãå¦â½£ãç§å®¤ãç§å®¤ä¸æå¸ä¸ºâ¼å¯¹å¤å ³ç³»ï¼æå¸ä¸ç级为å¤å¯¹å¤å ³ç³»ï¼ç级ä¸å¦â½£ä¸ºâ¼å¯¹å¤å ³ç³»ï¼ç§å®¤ä¸éä½ç°å±çº§å ³ç³»ââ
ââååºåå¼ è¡¨çé»è¾å段ââ
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ââ7ï¼è¯´ä¸ä¸ä½ çæçæ°æ®åºï¼è¿ä¸ªæ°æ®åºæä»ä¹ç¹ç¹ï¼ââ
ââ8ï¼ä½ 常ç¨çmysqlå¼ææåªäºï¼åå¼æé´æä»ä¹åºå«ï¼Â ââ
ââ9ï¼è¯·æè¿°MySQLä¸left joinåinner joinçåºå«ã ââ
ââ10ï¼è¯·ååºä½ æ常使⽤çmysqlçæ¬ï¼mysqlé»è®¤ç«¯â¼å·æ¯å¤å°ï¼è¯·ååºä½ æ常⽤çmysqlæ°æ®åºå¤ä»½åæ¢å¤å½ä»¤ã ââ
ââ11ï¼æ°æ®åºA:datahnï¼å ¶ä¸å ·æ表cã表dã æ°æ®åºB:datapubhnï¼ç°æ³è¦å¨æ°æ®åºBä¸å¯¹æ°æ®åºAä¸è¡¨cä¸è¡¨dä¸çå段è¿â¾å¢å æ¹æ¥ãå¦ä½ææï¼ââ
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å ï¼SQLè¿é¶é¢è¯é¢
1ï¼ä¸æ¡SQLè¯å¥æ¥è¯¢åºæææ绩大äº80çå¦çå§å
建表è¯å¥
-- 建表è¯å¥
CREATE TABLE `mst_stu` (
`name` varchar(255) DEFAULT NULL,
`course` varchar(255) DEFAULT NULL,
`score` int(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
-- æ°æ®
INSERT INTO `mst_stu` VALUES ('å¼ ä¸', 'è¯â½', 81);
INSERT INTO `mst_stu` VALUES ('å¼ ä¸', 'æ°å¦', 75);
INSERT INTO `mst_stu` VALUES ('æå', 'è¯â½', 76);
INSERT INTO `mst_stu` VALUES ('æå', 'æ°å¦', 90);
INSERT INTO `mst_stu` VALUES ('çäº', 'è¯â½', 81);
INSERT INTO `mst_stu` VALUES ('çäº', 'æ°å¦', 100);
INSERT INTO `mst_stu` VALUES ('çäº', 'è±è¯', 90);
解é¢æè·¯
æ ¹æ®å¦åè¿è¡åç»ï¼æä½åé«äº80å³ç¬¦åè¦æ±
-- å
æ ¹æ®å¦åè¿è¡åç»,çæ¯ä¸ªäººçæä½å
select name,min(score) from mst_stu group by name;
-- å¨ä½¿ç¨åç»è¿æ»¤ having çéåºæä½å大äº80
select name,min(score) as min_sc from mst_stu group by name having min_sc > 80;
-- æç»åªéè¦ç¬¦åè¦æ±çå¦åå§å
select name from mst_stu group by name having min(score) > 80;
2ï¼æ¥è¯¢åä¸å¤© temperature æ¯åä¸å¤©é«çdate
æ¥æ¾ä¸ä¹åï¼æ¨å¤©çï¼â½æç¸â½æ¸©åº¦æ´â¾¼çææâ½æç Idã
建表è¯å¥
-- mst_Weather
CREATE TABLE `mst_weather` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`date` date DEFAULT NULL,
`temperature` int(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4;
INSERT INTO `mst_weather` VALUES (1, '2022-04-01', 20);
INSERT INTO `mst_weather` VALUES (2, '2022-04-02', 25);
INSERT INTO `mst_weather` VALUES (3, '2022-04-03', 21);
INSERT INTO `mst_weather` VALUES (4, '2022-04-04', 24);
解é¢æè·¯
两个ç¸åç表åèªèç»ï¼èç»æ¡ä»¶æ¯s1表çæ¥æä¸s2表æ¥æä¹å·®ä¸º1ï¼ä¸s1表ç温度é«äºs2表ç温度
datediffç¨äºè®¡ç®ä¸¤ä¸ªæ¥æä¹å·®
select s1.id
from mst_weather as s1
join mst_weather as s2
on datediff(s1.date,s2.date) = 1
and s1.temperature > s2.temperature;
3ï¼æ¥è¯¢æ¯ä¸ªä¸»æçæ大level以å对åºçæå°gap(注æ:ä¸æ¯æ¯ä¸ªä¸»æçæ大levelåæå°gap)
é¦å éå®æ大çlevelï¼å ¶æ¬¡æéæå°çgap
建表è¯å¥
CREATE TABLE `mst_zhubo` (
`zhubo_id` int(11) NOT NULL,
`level` int(255) DEFAULT NULL,
`gap` int(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `mst_zhubo` VALUES (123, 8, 20);
INSERT INTO `mst_zhubo` VALUES (123, 9, 40);
INSERT INTO `mst_zhubo` VALUES (123, 9, 30);
INSERT INTO `mst_zhubo` VALUES (246, 6, 30);
INSERT INTO `mst_zhubo` VALUES (246, 6, 20);
解é¢æè·¯
-- å
æ¥è¯¢æ¯ä¸ªä¸»æçæ大 level
select zhubo_id,max(level) from mst_zhubo group by zhubo_id;
+----------+------------+
| zhubo_id | max(level) |
+----------+------------+
| 123 | 9 |
| 246 | 6 |
+----------+------------+
2 rows in set (0.00 sec)
--å¨è¿ä¸ªåºç¡ä¸,æ¥è¯¢åºæ¯ä¸ªä¸»æææ符åæ大levelçæ°æ®
select * from mst_zhubo where (zhubo_id,level) in (select zhubo_id,max(level) from mst_zhubo group by zhubo_id)
+----------+-------+------+
| zhubo_id | level | gap |
+----------+-------+------+
| 123 | 9 | 40 |
| 123 | 9 | 30 |
| 246 | 6 | 30 |
| 246 | 6 | 20 |
+----------+-------+------+
4 rows in set (0.01 sec)
-- å¨è¿ä¸ªåºç¡ä¸,æç
§ä¸»æåç»,æ±æå°çgap
select zhubo_id,level,min(gap)
from mst_zhubo where (zhubo_id,level) in (select zhubo_id,max(level) from mst_zhubo group by zhubo_id)
group by zhubo_id,level;
+----------+-------+----------+
| zhubo_id | level | min(gap) |
+----------+-------+----------+
| 123 | 9 | 30 |
| 246 | 6 | 20 |
+----------+-------+----------+
2 rows in set (0.01 sec)
4ï¼è¯¾ç¨æ°æ®è¡è½¬å
建表è¯å¥
CREATE TABLE `mst_class` (
`class_id` varchar(255) NOT NULL,
`grade` varchar(255) DEFAULT NULL,
`rate` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
INSERT INTO `mst_class` VALUES ('abc123', 'primary', '70%');
INSERT INTO `mst_class` VALUES ('abc123', 'middle', '65%');
INSERT INTO `mst_class` VALUES ('abc123', 'high', '72%');
INSERT INTO `mst_class` VALUES ('hjkk86', 'primary', '69%');
INSERT INTO `mst_class` VALUES ('hjkk86', 'middle', '63%');
INSERT INTO `mst_class` VALUES ('hjkk86', 'high', '74%');
解é¢æè·¯
使ç¨case-when / if-elseè¯å¥éæ©ååçå¼ï¼å¹¶åæ大å¼è¿è¡æ¿æ¢
--CASE WHEN
select class_id,
max(CASE WHEN grade = 'primary' THEN rate ELSE 0 END) as 'primary',
max(CASE WHEN grade = 'middle' THEN rate ELSE 0 END) as 'middle',
max(CASE WHEN grade = 'high' THEN rate ELSE 0 END) as 'high'
from mst_class
group by class_id;
--IF
select class_id,
max(IF(grade = 'primary',rate,0)) as 'primary',
max(IF(grade = 'middle',rate,0)) as 'middle',
max(IF(grade = 'high',rate,0)) as 'high'
from mst_class
group by class_id;
5ï¼æ两个表AåBï¼åækeyåvalue两个å段ï¼å¦æBçkeyå¨Aä¸ä¹æï¼å°±æBçvalueæ¢ä¸ºAä¸å¯¹åºçvalue
建表è¯å¥
create table `mst_a`(`key` varchar(10),`value` varchar(10));
create table `mst_b`(`key` varchar(10),`value` varchar(10));
insert into mst_a values('A','aaa'),('B','bbb'),('C','ccc');
insert into mst_b values('D','ddd'),('E','eee'),('A','abc');
解é¢æè·¯
-- å
æ¥è¯¢åºåªä¸ªkey符åè¦æ±?
select mst_a.key,mst_a.value from mst_a join mst_b on mst_a.key = mst_b.key;
-- update mst_b as up ,(?) as b set up.value = ? where up.key = ?
update mst_b as up,(
select mst_a.key,mst_a.value from mst_a join mst_b on mst_a.key = mst_b.key
) as b
set up.value = b.value where up.key = b.key
注æäºé¡¹
- update åé¢æ¯å¯ä»¥è¿è¡ä»»ä½æ¥è¯¢è¯å¥,è¿ä¸ªä½ç¨çåäº from
- update æ´æ°ç表,ä¸è½å¨setåwhereä¸ç¨äºåæ¥è¯¢
- update ä¹å¯ä»¥å¯¹å¤ä¸ªè¡¨è¿è¡æ´æ° (sqlserverä¸è¡)
6ï¼è®¾è®¡è¡¨ï¼å ³ç³»å¦ä¸ï¼æå¸ãç级ãå¦â½£ãç§å®¤ãç§å®¤ä¸æå¸ä¸ºâ¼å¯¹å¤å ³ç³»ï¼æå¸ä¸ç级为å¤å¯¹å¤å ³ç³»ï¼
ç级ä¸å¦â½£ä¸ºâ¼å¯¹å¤å ³ç³»ï¼ç§å®¤ä¸éä½ç°å±çº§å ³ç³»
ååºåå¼ è¡¨çé»è¾å段
æå¸ mst_Teacher
+-----+-----------+------+
| Tid | Tname | Kid |
+-----+-----------+------+
| 1 | çâ½¼å¸ | 1 |
| 2 | å¼ â½¼å¸ | 2 |
| 3 | åâ½¼å¸ | 3 |
| 4 | æâ½¼å¸ | 3 |
| 5 | ä¼â½¼å¸ | 4 |
+-----+-----------+------+
CREATE TABLE `mst_teacher` (
`Tid` int PRIMARY KEY AUTO_INCREMENT,
`Tname` varchar(10),
`Kid` int
);
insert into mst_teacher VALUES(1,'çâ½¼å¸',1),(2,'å¼ â½¼å¸',2),(3,'åâ½¼å¸',3),
(4,'æâ½¼å¸',3),(5,'ä¼â½¼å¸',4);
ç级 mst_cla
+-----+-------+
| Cid | Cname |
+-----+-------+
| 1 | 1ç |
| 2 | 2ç |
| 3 | 3ç |
+-----+-------+
CREATE TABLE `mst_cla` (
`Cid` int PRIMARY KEY AUTO_INCREMENT,
`Cname` varchar(10)
);
insert into mst_cla VALUES(1,'1ç'),(2,'2ç'),(3,'3ç');
æå¸&ç级 mst_tc
+----+------+------+
| id | Tid | Cid |
+----+------+------+
| 1 | 3 | 1 |
| 2 | 3 | 2 |
| 3 | 3 | 3 |
| 4 | 4 | 1 |
| 5 | 4 | 2 |
| 6 | 4 | 3 |
+----+------+------+
CREATE TABLE `mst_tc` (
`id` int PRIMARY KEY AUTO_INCREMENT,
`Tid` int,`Cid` int
);
insert into mst_tc VALUES(1,3,1),(2,3,2),(3,3,3),(4,4,1),(5,4,2),(6,4,3);
å¦â½£ mst_St
+-----+--------+------+
| SId | Sname | Cid |
+-----+--------+------+
| 1 | èµµé· | 1 |
| 2 | é±çµ | 1 |
| 3 | åâ» | 1 |
| 4 | æäº | 2 |
| 5 | å¨æ¢
| 2 |
| 6 | å´å
° | 3 |
| 7 | éâ½µ | 3 |
+-----+--------+------+
CREATE TABLE `mst_St` (
`SId` int PRIMARY KEY AUTO_INCREMENT,
`Sname` varchar(20),`Cid` int
);
insert into mst_St VALUES(1,'èµµé·',1),(2,'é±çµ',1),(3,'åâ»',1),(4,'æäº',2),
(5,'å¨æ¢
',2),(6,'å´å
°',3),(7,'éâ½µ',3);
ç§å®¤ mst_ks
+-----+-------------+------+
| Kid | Kname | Pid |
+-----+-------------+------+
| 1 | æ ¡â»å®¤ | 0 |
| 2 | æå¦å¤ | 1 |
| 3 | uiåå
¬å®¤ | 2 |
| 4 | h5åå
¬å®¤ | 2 |
+-----+-------------+------+
CREATE TABLE `mst_ks` (
`Kid` int PRIMARY KEY AUTO_INCREMENT,
`Kname` varchar(20),`Pid` int
);
insert into mst_ks VALUES(1,'æ ¡â»å®¤',0),(2,'æå¦å¤',1),(3,'uiåå
¬å®¤',2),(4,'h5åå
¬
室',2);
é®é¢
æ¥è¯¢æå¸id=4çå¦â½£æ°
-- å·²ç¥æå¸Idå°±å¯ä»¥å
å°æå¸ä¸ç级çå
³ç³»è¡¨ä¸è·åå½åâ½¼å¸æ带çç级
select cid from mst_tc where Tid = 4;
-- è·åæ带ç级å,å°å¦â½£è¡¨ä¸è·åæ带ç级ä¸çå¦åæ°å³å¯
select count(*) from mst_St where Cid in (select cid from mst_tc where Tid =
4);
æ¥è¯¢ç§å®¤id=2çä¸çº§é¨â»æ°
-- ç§å®¤id=3çä¸çº§é¨â»çpidä¹å°±çäºç§å®¤id,å æ¤æ¥è¯¢å½åç§å®¤çâ½çº§id = 2çå³å¯
select count(*) from mst_ks where pid = 2;
æ¥è¯¢æ带å¦â½£æå¤çæå¸id
-- å
æ¥è¯¢åºæ¯ä¸ªâ½¼å¸å¸¦çå¦â½£æ°
select t.tid,t.tname,count(stu.sid)
from mst_teacher as t join mst_tc on t.tid = mst_tc.tid
join mst_st as stu on stu.cid = mst_tc.cid
group by t.tid,t.tname;
+-----+-----------+----------------+
| tid | tname | count(stu.sid) |
+-----+-----------+----------------+
| 3 | åâ½¼å¸ | 7 |
| 4 | æâ½¼å¸ | 5 |
+-----+-----------+----------------+
-- å¨ä»¥ä¸ç»æçåºç¡ä¸,æç
§å¦â½£æ°æåº,åâ¼ä¸ª
select t.tid,t.tname,count(stu.sid) as num
from mst_teacher as t join mst_tc on t.tid = mst_tc.tid
join mst_st as stu on stu.cid = mst_tc.cid
group by t.tid,t.tname order by num desc limit 1;
7ï¼è¯´ä¸ä¸ä½ çæçæ°æ®åºï¼è¿ä¸ªæ°æ®åºæä»ä¹ç¹ç¹ï¼
mysql å ³ç³»åæ°æ®åº å¼æºä¸æ常⽤çæ°æ®åº,æå¤ç§è¡¨å¼æ,â½æäºå¡,â½æè¡¨å ³ç³»Â
redis éå ³ç³»åæ°æ®åº,é®å¼å¯¹çåå¨â½ å¼,并ä¸æ°æ®åå¨å¨å åä¸,æå¤ç§ä¸åçæ°æ®ç±»åÂ
mongodb éå ³ç³»åæ°æ®åº,åºäºåå¸å¼â½ä»¶åå¨çæ°æ®åº,æ¯nosqlä¸æåå ³ç³»åæ°æ®åºç
8ï¼ä½ 常ç¨çmysqlå¼ææåªäºï¼åå¼æé´æä»ä¹åºå«ï¼Â
myisam åå¨ç±ä¸ä¸ªâ½ä»¶ç»æ,â¼ä¸ªåå¨è¡¨ç»æ,â¼ä¸ªåå¨æ°æ®,â¼ä¸ªåå¨ç´¢å¼ãä¸â½æäºå¡,â¾®èç°ç´¢å¼Â
innodb åå¨ç±ä¸¤ä¸ªâ½ä»¶ç»æ,â¼ä¸ªåå¨è¡¨ç»æ,â¼ä¸ªåå¨æ°æ®åç´¢å¼ãâ½æäºå¡,主索å¼æ¯èç°ç´¢å¼,并ä¸è¡¨ä¸å§ç»åå¨ä¸»é®(å³ä¾¿å¨å»ºè¡¨æ¯æ²¡æå建主é®)
9ï¼è¯·æè¿°MySQLä¸left joinåinner joinçåºå«ãÂ
join å inner join é½æ¯â¼æ ·ç,ä¼è¿æ¥ä¸¤ä¸ªè¡¨ä¸åå¨å ³ç³»å段çæ°æ® å whereçå ³èæ¥è¯¢â¼æ ·
left join å right joinâ¼æ · é½æ¯ä»¥å·¦è¡¨(æå³è¡¨)æ°æ®ä¸ºåºå,å»æ¥è¯¢å¦å¤â¼ä¸ªè¡¨çæ°æ®, å¦æ没æ对åºå段çæ°æ®,åè¡¥å 为null
10ï¼è¯·ååºä½ æ常使⽤çmysqlçæ¬ï¼mysqlé»è®¤ç«¯â¼å·æ¯å¤å°ï¼è¯·ååºä½ æ常⽤çmysqlæ°æ®åºå¤ä»½åæ¢å¤å½ä»¤ãÂ
5.7, 端⼠3306 127.0.0.1 localhost æ¬æºçIP
-- æ°æ®å¯¼â¼ mysql -uroot -p < F:\mysql-5.7.27-winx64\bf\ops.sql
-- æ°æ®å¤ä»½ å¯¼åº mysqldump -uroot -p -B -F -R -x --master-data=2 ops >F:\mysql-5.7.27-winx64\bf\ops.sql
åæ°è¯´æï¼
-Bï¼æå®æ°æ®åº -Fï¼å·æ°â½å¿ -Rï¼å¤ä»½åå¨è¿ç¨ç -xï¼é表 --master-dataï¼å¨å¤ä»½è¯å¥â¾¥æ·»å CHANGE MASTERè¯å¥ä»¥åbinlogâ½ä»¶åä½ç½®ç¹ä¿¡æ¯
11ï¼æ°æ®åºA:datahnï¼å ¶ä¸å ·æ表cã表dã æ°æ®åºB:datapubhnï¼ç°æ³è¦å¨æ°æ®åºBä¸å¯¹æ°æ®åºAä¸è¡¨cä¸è¡¨dä¸çå段è¿â¾å¢å æ¹æ¥ãå¦ä½ææï¼
grant select,insert,update,delete on B.*,A.c,A.d to'zhansgan'@'%' identified by '123456
12ï¼å¯¹äºå¤çâ¾¼å¤æsqlï¼æ°æ®åºæ¥è¯¢ç¹å«æ ¢ï¼ä½ æä»ä¹é«æï¼Â
- å¤ææ¥è¯¢ç®åå
- ä¸â½¤åµå¥
- ä¸â½¤join
- å¤è¡¨æ¥è¯¢
- æå
- é对è¯å¥çæ¥è¯¢å段设计索å¼ï¼ç»ç»å¸¸ä½ä¸ºwhereæ¡ä»¶çå段添å ç´¢å¼ï¼å¿ è¦æ¶æ·»å èåç´¢å¼
13ï¼éæ©å¡«ç©ºé¢
以ä¸åªæ¡è¯å¥å¨æ°æ®åºsql书åæ¶æ为⾼æï¼Bï¼
- A.select * from emp where dep>3
- B.select * from emp where dep>=4
- C.select * from emp where depâ¥4
- D.select * from emp where dep>=3 and depâ 4
æ°æ®åºä¸æ§â¾å é¤æä½ï¼è¥è¦å é¤è¡¨ä¸çææâ¾ï¼å»ºè®®ä½¿â½¤ï¼Bï¼
- A.delete è¯å¥
- B.turncate è¯å¥
- C.drop è¯å¥
- D.commit è¯å¥
å¨æ¥è¯¢è¯å¥çselect⼦å¥ä¸å°½éé¿å 使⽤ * æ¥è¡¨ç¤ºå ¨é¨åå
æ¥æ¾æ¡ä»¶ä¸ºï¼å§åä¸æ¯NULLç纪å½ï¼Cï¼
- A.WHERE NAME ! NULL
- B.WHERE NAME NOT NULL
- C.WHERE NAME IS NOT NULL
- D.WHERE NAME!=NULL
å¨SQLè¯â¾ä¸ï¼â¼¦æ¥è¯¢æ¯ï¼Dï¼
- A.éåå表ä¸å段⼦éçæ¥è¯¢è¯å¥
- B.éåå¤è¡¨ä¸å段⼦éçæ¥è¯¢è¯å¥
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- D.åµâ¼å°å¦â¼ä¸ªæ¥è¯¢è¯å¥ä¹ä¸çæ¥è¯¢è¯å¥
以ä¸è½å¤å é¤â¼åçæ¯ï¼Bï¼
- A.alter table emp remove addcolumn
- B.alter table emp drop column addcolumn
- C.alter table emp delete column addcolumn
- D.alter table emp delete addcolumn
å¦â½£å ³ç³»æ¨¡åS(S#,Sname,Sex,Age),Sçå±æ§åå«è¡¨ç¤ºå¦â½£çå¦å·ãå§åãæ§å«ãå¹´é¾ãè¦å¨è¡¨Sä¸å é¤â¼ä¸ªå±æ§âå¹´é¾â,å¯é⽤çSQLè¯å¥æ¯ï¼Dï¼
- A.UPDATE S Age
- B.DELETE Age from S
- C.ALTER TABLE S âAgeâ
- D.ALTER TABLE S DROP Age
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