


MySQL_Implementing intra-group sorting-the function of rank() function in Oracle
Suppose the table is student, and the data is as follows:
We want to implement the rank() function in Oracle in MySQL, that is, sorting within the group, specifically: It is to rank the students (name) in the student table according to the course (course) and according to the score (score).
First create a new stored procedure realize_rank_in_MySQL, the code is as follows: # ##
DROP PROCEDURE IF EXISTS realize_rank_in_MySQL; DELIMITER ;; CREATE PROCEDURE realize_rank_in_MySQL() BEGIN DECLARE i int; SET i = 0; WHILE i < (select count(DISTINCT course) from student) DO SET @ROW =0; INSERT INTO student_rank SELECT *, (@ROW:=@ROW+1) AS rank FROM student WHERE course=(select DISTINCT course from student limit i,1) ORDER BY score DESC; set i = i + 1; END WHILE; END ;; DELIMITER ;
drop table if exists student_rank; create table student_rank like student; alter table student_rank add rank int; call realize_rank_in_MySQL; select * from student_rank;
Note: The ranking here does not realize the situation where the ranking is the same when the scores are the same.
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Using standard sql in hive to implement intra-group sorting
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