How to pivot tables in MySQL

Question

I have a question about how to pivot the table in MySQL. I have a dataset, columns like this:

ID   Name     job_title
1    Sam       Fireman
2    Tomas     Driver
3    Peter     Fireman
4    Lisa      Analyst
5    Marcus    Postman
6    Stephan   Analyst
7    Mary      Research Manager
8    Albert    Analyst
9    Chen      Driver
...etc...

And I want to generate a table like this:

Fireman  Driver   Analyst  Postman   Research Manager ...
Sam     Tomas     Lisa     Marcus     Mary
Peter   Chen      Stephan  (someone)  (someone)...
....etc...

Since, this is just a sample from the datasets, so I may not know how much different job titles in the dataset. The goal is to list every person in the different job title columns.

Is there any methods to do that? Or is it possible to generate such table in MySQL? An engineer told me that it can done by creating a view, but I do not know how. I read some books, and still confused.

Any ideas and SQL queries guides are welcome!

Answer 1

There are 3 things to think about 1) How to dynamically generate a bunch of max(case when 2) assigning something to group the case when's by - in this case I generate a row number using a variable 3) some of your job titles contain white space which I remove for the generation of column headers

set @sql = 
            (select concat('select ', gc,            ' from 
             (select name,job_title,
                if (job_title <> @p, @rn:=1 ,@rn:=@rn+1) rn,
                @p:=job_title p
                from t
                cross join (select @rn:=0,@p:=null) r
                order by job_title
              ) s group by rn;') from
            (select 
                group_concat('max(case when job_title = ', char(39),job_title ,char(39),' then name else char(32) end ) as ',replace(job_title,char(32),'')) gc
                from
                (
                select distinct job_title from t
                ) s
                ) t
             )
;           

Generates this sql code

select max(case when job_title = 'Fireman' then name else char(32) end ) as Fireman,
        max(case when job_title = 'Driver' then name else char(32) end ) as Driver,
        max(case when job_title = 'Analyst' then name else char(32) end ) as Analyst,
        max(case when job_title = 'Postman' then name else char(32) end ) as Postman,
        max(case when job_title = 'Research Manager' then name else char(32) end ) as ResearchManager
         from 
             (select name,job_title,
                if (job_title <> @p, @rn:=1 ,@rn:=@rn+1) rn,
                @p:=job_title p
                from t
                cross join (select @rn:=0,@p:=null) r
                order by job_title
              ) s group by rn;

Which can be submitted to dynamic sql

prepare sqlstmt from @sql;
execute sqlstmt;
deallocate prepare sqlstmt;

result

+---------+--------+---------+---------+-----------------+
| Fireman | Driver | Analyst | Postman | ResearchManager |
+---------+--------+---------+---------+-----------------+
| Sam     | Tomas  | Lisa    | Marcus  | Mary            |
| Peter   | Chen   | Stephan |         |                 |
|         |        | Albert  |         |                 |
+---------+--------+---------+---------+-----------------+
3 rows in set (0.00 sec)