MySQL how to form query - mysql

Question

I have 2 mysql tables I'm working with.
Table 1 has employee information columns :
employee_number, date_of_birth, name, address, etc.
Table 2 has pay information columns : employee_number (foreign key), date, bonus
My boss has requested a screen to show the data like, with dates listed horizontally across the top and employee listed vertically :
1/1/2000 | 1/1/2001 | 1/1/2002 | 1/1/2003
Bill $500 | $600 | $700 | $900
Ferdie $300 | $500 | $800 | $434
Tony $450 | $234 | $432 | $343
What is the easiest way to format my query so that the dataset is in this format?

Answer 1

What you need is a pivot table.
MySQL does not have a built in way to create a pivot table, but you can create it "by hand":
SQL Fiddle
MySQL 5.6 Schema Setup:
create table employees(
employee_number int primary key,
name varchar(50)
);
create table payments(
employee_number int,
bonus_date date,
bonus decimal(8,2)
);
insert into employees values
(1, 'Bill'), (2, 'Freddie'), (3, 'Tony');
insert into payments values
(1, '2000-1-1',500),(1, '2001-1-1',600),(1, '2002-1-1',700),(1, '2003-1-1',900),
(2, '2000-1-1',300),(2, '2001-1-1',500),(2, '2002-1-1',800),(2, '2003-1-1',434),
(3, '2000-1-1',450),(3, '2001-1-1',234),(3, '2002-1-1',432),(3, '2003-1-1',343);
Query 1:
-- 1. Prepare the column definition
select group_concat(distinct
concat(
"sum(case when bonus_date='", bonus_date, "' then bonus else 0 end) as `", bonus_date, "`"
)
)
into #sql
from payments
Results: No results
Query 2:
-- 2. Write the full query
set #sql = concat("select e.employee_number, e.name, ", #sql, " from employees as e inner join payments as p on e.employee_number = p.employee_number group by e.employee_number")
Results: No results
Query 3:
-- 3. Check the generated query (optional)
-- select #sql
Results: (uncomment the above query and check the result)
Query 4:
-- 4. Create a prepared statement using the query you've just created
prepare stmt from #sql
Results: No results
Query 5:
-- 5. Execute the prepared statement
execute stmt
Results:
| employee_number | name | 2000-01-01 | 2001-01-01 | 2002-01-01 | 2003-01-01 |
|-----------------|---------|------------|------------|------------|------------|
| 1 | Bill | 500 | 600 | 700 | 900 |
| 2 | Freddie | 300 | 500 | 800 | 434 |
| 3 | Tony | 450 | 234 | 432 | 343 |
Query 6:
-- 6. When you're done, deallocate the prepared statement
deallocate prepare stmt
Results: No results
You may want to check my answer on a similar question.
Hope this helps.