MySQL - Limit limit query

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        Introduction: MySQL series of operations fierce as a tiger, the code clear and easy to understand, simple structure, today let's talk about MySQL limit restriction inside the query.

1, Limit grammar

     Limit limit the query, by definition, limit the number of bars displayed after the query results, it should be noted that if the use limit 3 represents three records before the restrictions, if the limit 3,5 indicates the start of the display from Article 4 records show a total of five. Due to the wide application of this method, it is classified as a separate article, for your taste!

2, create a table

     The story needs to create scores of students scoring form

create table scores (s_id varchar(5),
    c_id varchar(3),score float);
    
insert into score values 
("001","01",135),
("005","01",120),
("003","01",110),
("002","01",90),
("005","02",140),
("001","02",125.5),
("004","02",100),
("006","02",90),
("002","03",102),
("005","03",100.6),
("001","03",100),
("003","03",95.6),
("004","03",83),
("003","02",80),
("006","03",79.5);

3, section title

Topic one: The first three tables show student achievement records

select * from scores limit 3;
# 答案 ：
001	01	135
005	01	120
003	01	110

Topic two: the top three scores query results information

select * from scores order by score desc limit 3; # 法一

select * from scores order by score desc limit 0,3; # 法二
# 答案 ：
005	02	140
001	01	135
001	02	126

Topic three: The third query results to a fifth-place performance information

select * from scores order by score desc limit 2,3;
# 答案 :
001	02	126
005	01	120
003	01	110

Topic Four: Query number of students than 002 students of all course grades are high performance information
     analysis: here all grades are higher than 002, 002 must be higher than the highest score, then use the sub-query finds the maximum 002 points, then let's look to score greater than 002 the highest score you can.

select scores.* from scores where score>
 (select max(score) from scores where s_id=002); # 法一
 
 
select scores.* from scores where score>
 (select max(score) from scores group by s_id having s_id=002); # 法二

 
select scores.* from scores where score>
 (select score from scores where s_id=002 order by score desc limit 1);# 法三
# 答案 ： 
001	01	135
005	01	120
003	01	110
005	02	140
001	02	126

Topic five: three queries before the average score of 100 points or greater student achievement information

select * from scores where s_id in 
   (select s_id from scores group by s_id having avg(score)>=100)limit 3;
# 答案 ：
001	01	135
005	01	120
005	02	140

4, the end of the paper eggs - Kaixinyike

       This folks, do not live too tired, and sometimes have to give yourself some fun. This is not just a few days ago Well, me and my friend went to the Cubs to their house. Then his father play it in the phone, we watch TV, at this time it aunt told my uncle to dial the garlic. I'm bored Well, flipped through the phone to see 'China Mobile customer service hotline', I reflected heard to China Mobile to send text messages for free, then sends the information gave China Mobile customer service hotline: "! I miss you", a there will come back: "I want to come to me, ah, the devil." Mother ah! I'm surprised, mobile customer turned out to be alive ... scared I quickly put down the phone ... my uncle. But I think his dad lively, I should probably wondering like his father to learn, so I plan to add his father's micro letter, refused to add the results of such information sent to me: Do not bother me, I already have a family, I love my wife a person for life, even Fan Bingbing came and I love my wife, is such a case.
       So your blogger friends, do not let your wife read this article! But you clicked concern, I would not take your cell phone to send text messages, ha ha ha

          Today to end here - each article has the final end of the paper eggs - relaxed moment yo Thanks for watching, I was Jetuser-data [learn more knowledge please add MySQL concern]

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