seulement si vous avez moins de 10 000 e-mails... est-ce acceptable ?
select
if(t1.c > 1, concat(e.employeename, ' (', e.employeeid, ')'), e.employeename) as Employee,
replace(substring(substring_index(e.EmailAddresses, ',', n.row), length(substring_index(e.EmailAddresses, ',', n.row - 1)) + 1), ',', '') EmailAddress
from
(select employeename, count(*) as c from Employees group by employeename) as t1,
(select EmployeeID, length(EmailAddresses) - length(replace(EmailAddresses,',','')) + 1 as emails from Employees) as t2,
(SELECT @row := @row + 1 as row FROM
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) x,
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) x2,
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) x3,
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) x4,
(SELECT @row:=0) as ff) as n,
Employees e
where
e.employeename = t1.employeename and
e.employeeid = t2.employeeid and
n.row <= t2.emails
order by e.employeeid;
MODIF :
Avec moins de numéros inutiles générés :
select
if(t1.c > 1, concat(e.EmployeeName, ' (', e.EmployeeID, ')'), e.EmployeeName) as Employee,
replace(substring(substring_index(e.EmailAddresses, ',', n.row), length(substring_index(e.EmailAddresses, ',', n.row - 1)) + 1), ',', '') as EmailAddress
from
(select EmployeeName, count(*) as c from Employees group by EmployeeName) as t1,
(select EmployeeID, length(EmailAddresses) - length(replace(EmailAddresses,',','')) + 1 as emails from Employees) as t2,
(select `1` as row from (select 1 union all select 2 union all select 3 union all select 4) x) as n,
Employees e
where
e.EmployeeName = t1.EmployeeName and
e.EmployeeID = t2.EmployeeID and
n.row <= t2.emails
order by e.EmployeeID;
Et qu'avons-nous appris ? Une mauvaise conception de la base de données entraîne des requêtes épouvantables. Et vous pouvez faire des choses avec SQL, qui ne sont probablement prises en charge que parce que les gens conçoivent mal les bases de données... :)
