格式化MySQL查询结果

Question

let me start off with the fact that i'm still kind of new to php/mysql.

I'm trying to build a system that can be used to record jobs completed for customers that keeps track of job numbers, customer name, equipment, dates, and employee's assigned to the task.

I have a table setup to handle the employee's assigned, but I can't seem to figure out how to format the results the way I would like.

There could be multiple employee's assigned to the same job over several days. So I setup a table like:

job_ID  |  employee_name  |  date_worked  |  hours_worked
  1     |      Dave       |   2010-1-2    |     4.5
  1     |      Dave       |   2010-1-3    |     4.0
  1     |      Mike       |   2010-1-2    |     6.0
  2     |      Bill       |   2011-5-7    |     8.0
  2     |      Bill       |   2011-5-8    |     6.5
  2     |      Dave       |   2011-5-7    |     4.0
  2     |      Dave       |   2011-5-8    |     4.5

What i'm looking to do with the results is output it like:

    Job # = 1
    Employee  |  2010-1-2  |  2010-1-3  | 
      Dave    |     4.5    |     4.0    |
      Mike    |     6.0    |      0     |

    Job # = 2
    Employee  |  2011-5-7  |  2011-5-8  | 
      Bill    |     8.0    |     6.5    |
      Dave    |     4.0    |     4.5    |

Can anyone offer advice?

EDIT

Ok, so I guess I left out some information.

I have a table (job_list) that is used to keep records.

This table records the job_id, client, equipment, location, call date, response date, completion date, etc.

Then I have a table (employee_list) that lists all employees by id, and name.

The idea behind the table I posted earlier was to be the table that just records who was where, on what day, and for how long.

I've amended the table i posted to have employee_id.

And I would like to display the results in php to look like the output i posted. I just don't know how to do it.

What other information can I provide? Apologies for my lack of understanding on what I need to post :-/

And if my approach is completely horrible, I did say I'm still new to this...

Answer 1

This is basically a PIVOT but MySQL does not have a PIVOT function so you will need to replicate it using an aggregate function and a CASE statement. If you know all of the values that you want to transform your query will be similar to this:

select employee_name,
  sum(case when date_worked = '2010-01-02' then hours_worked else 0 end) `2010-01-02`,
  sum(case when date_worked = '2010-01-03' then hours_worked else 0 end) `2010-01-03`
from yourtable
group by employee_name

See SQL Fiddle with Demo

The result is:

| EMPLOYEE_NAME | 2010-01-02 | 2010-01-03 |
-------------------------------------------
|          Bill |          0 |          0 |
|          Dave |        4.5 |          4 |
|          Mike |          6 |          0 |

If you have an unknown number of values, then you can use a prepared statement to generate this dynamically:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'sum(case when date_worked = ''',
      date_worked,
      ''' then hours_worked else 0 end) AS `',
      date_worked, '`'
    )
  ) INTO @sql
FROM yourtable;

SET @sql = CONCAT('SELECT employee_name, ', @sql, ' 
                  FROM yourtable 
                   GROUP BY employee_name');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

See SQL Fiddle with Demo

Both will produce the same result.