UNION three different SELECTs in MYSQL - mysql

Question

I have this MYSQL table named people with the columns: id|firstname|lastname|birthdate|phone.
I am quite new to MYSQL and I'm trying to UNION several SELECTs so that the result will look in the following way:
only the first 20 results must be shown
the first SELECT criteria is by the combination firstname+lastname+birthdate: WHERE (birthdate="1980-01-01") AND ((firstname LIKE "%john%") AND (lastname LIKE "%smith%"))
the second SELECT criteria is by the combination firstname+lastname: WHERE (firstname LIKE "%john%") AND (lastname LIKE "%smith%")
the third SELECT criteria is by phone: WHERE phone="0123456"
the output result must in fact have 3 columns: order|id|type; where "order" and "type" are alias columns
the exported ids must be unique: if the same id results from all the 3 SELECTs (or from more than one SELECT), then it must appear only once in the output table
the column "order" must have the value 1 for the results of the first SELECT, 2 for the 2nd SELECT and 3 for the last SELECT
if the same id value results from more than one SELECT, then its row must have the highest order value; where the highest order posible is 1, from the first SELECT
the alias column "type" must work like this: if an id results from the 1st SELECT, it's type value is "~firstname+lastname+birthdate~"; if an id results from the 2nd SELECT, it's type value is "~firstname+lastname~"; and finally if an id results from the 3rd SELECT, it's type value is "~phone~"
if the same id value results from more than one SELECT, the value on the "type" alias column must be a concatention between the SELECTs where that id was found (for example, if the same id resulted in all 3 SELECT queries then the value on the "type" column would be "~firstname+lastname+birthdate~~firstname+lastname~~phone~")
Is it possible to achieve such an output?

Answer 1

Here's something using CASE statements. I think you'll get into a mess with union statements, because of your order type statement. Hopefully I've understood what you're after - it's much easier if you post sample data! Anyway, even if this doesn't do exactly what you want, you get the idea....
[EDIT] I don't think you need the distinct, but I don't think it hurts, either...
SELECT DISTINCT
CASE WHEN birthdate='1980-01-01'
AND firstname LIKE '%john%' AND lastname LIKE '%smith%'
THEN 1
WHEN firstname LIKE '%john%' AND lastname LIKE '%smith%'
THEN 2
WHEN phone='0123456'
THEN 3
END AS outputorder, -- avoid confusion of using an SQL keyword as a column name,
id,
CONCAT(
CASE
WHEN birthdate='1980-01-01'
AND firstname LIKE '%john%' AND lastname LIKE '%smith%'
THEN CONCAT('~',firstname,'+',lastname,'+','~')
END ,
CASE WHEN firstname LIKE '%john%' AND lastname LIKE '%smith%'
THEN CONCAT('~',firstname,'+',lastname,'~')
END ,
CASE WHEN phone='0123456'
THEN CONCAT('~',phone,'~')
END
) -- end the concat
AS outputtype
FROM
mytable
WHERE
( birthdate='1980-01-01'
AND firstname LIKE '%john%' AND lastname LIKE '%smith%')
OR
(firstname LIKE '%john%' AND lastname LIKE '%smith%')
OR
phone='0123456'
ORDER by 1,2 LIMIT 20

Answer 2

In the end I did something like this and it worked just fine:
SELECT MIN(`ord`) AS `order` , `id` , GROUP_CONCAT(`spec`) as `type` FROM (
SELECT "1" AS `ord` , `id` , "~firstname+lastname+birthdate~" AS `spec` FROM `people` WHERE (`birthdate` = "1986-04-02") AND (`lastname` LIKE "%smith%") AND (`firstname` LIKE "%john%")
UNION
SELECT "2" AS `ord` , `id` , "~firstname+lastname~" AS `spec` FROM `people` WHERE (`lastname` LIKE "%smith%") AND (`firstname` LIKE "%john%")
UNION
SELECT "3" AS `ord` , `id` , "~phone~" AS `spec` FROM `people` WHERE (`phone`="0123456")
) final
GROUP BY final.`id`
ORDER BY `order` ASC
LIMIT 20
Thanks to mlinth for the alternative though...