mysql 中支不支持pivot

mysql 中支不支持pivot

支持，代码如下：
"pivot table" or a "crosstab report"
(Note: this page needs to be wikified)
SQL Characteristic Functions: Do it without "if", "case", or "GROUP_CONCAT".
Yes, there is use for this..."if" statements sometimes cause problems
when used in combination.

The simple secret, and it's also why they work in almost all databases, is the
following functions:

o sign (x) returns -1,0, +1 for values x < 0, x = 0, x > 0 respectively
o abs( sign( x) ) returns 0 if x = 0 else, 1 if x > 0 or x < 0
o 1-abs( sign( x) ) complement of the above, since this returns 1 only if x = 0

Quick example: sign(-1) = -1, abs( sign(-1) ) = 1, 1-abs( sign(-1) ) = 0

Data for full example:

CREATE TABLE exams (
pkey int(11) NOT NULL auto_increment,
name varchar(15),
exam int,
score int,
PRIMARY KEY (pkey)
);

insert into exams (name,exam,score) values ('Bob',1,75);
insert into exams (name,exam,score) values ('Bob',2,77);
insert into exams (name,exam,score) values ('Bob',3,78);
insert into exams (name,exam,score) values ('Bob',4,80);

insert into exams (name,exam,score) values ('Sue',1,90);
insert into exams (name,exam,score) values ('Sue',2,97);
insert into exams (name,exam,score) values ('Sue',3,98);
insert into exams (name,exam,score) values ('Sue',4,99);

mysql> select * from exams;

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