multiple values in 1 column when you join 2 tables - mysql

table 1 - employee
id empname
--------------
1 andy
2 brady
table 2 - employee phone numbers
id number empid
----------------
1 1111 1
2 2222 2
3 3333 1
4 4444 1
Need a sql query to display the following
id empname numbers
------------------
1 andy 1111,3333,4444
2 brady 2222

If you are using MySQL, you can use GROUP_CONCAT funcion, that basically concatenate every value composing the group. You could try this:
SELECT EMP.ID,
EMP.EMPNAME,
GROUP_CONCAT(EPH.NUMBER) AS NUMBERS
FROM EMPLOYEE EMP
JOIN EMPLOYEE_PHONE EPH
ON EMP.ID = EPH.EMPID
GROUP BY EMP.ID
Also, if you want to separate your values with something different of a "," you can add the syntax SEPARATOR " " after the column inside group concat, if you want to separate with spaces in this particular example

if you use SQL SERVER I think this will do it for you, if not maybe a close guess without data. But! I used STUFF and selected the Number and split them by , and ordered it
SELECT
t1.ID,t2v1.empname,
STUFF((SELECT ',' + t2v2.number
FROM Table2 t2v2
WHERE t2v2.ID = t2v1.ID
ORDER BY number
FOR XML PATH('')), 1, 1, '') [numbers]
FROM Table1 t1
inner join table2 t2v1 on t1.id = t2v1.id
GROUP BY t1.ID, t1.Name
ORDER BY 1

Try this:
SELECT e.id, e.name, CONCATENATE(ep.number, ',') as phonelist
FROM Employees e INNER JOIN EmployeePhone ep ON e.id = ep.empid
Reference Doc: http://www.peteonsoftware.com/index.php/2009/12/11/creating-a-comma-separated-list-from-a-sql-grouping/

Related

Select From table name obtained dynamically from the query

I have 3 Tables
campaign1 (TABLE)
id campaign_details
1 'some detail'
campaign2 (TABLE)
id campaign_details
1 'some other detail'
campaign_list (TABLE)
id campaign_table_name
1 'campaign1'
2 'campaign2'
Campaign list table contains the table name of the two tables described above. I want to Select from the Campaign List table and get the record count using the table name i get from this select
For eg.
using select i get campaign1(Table name). Then i run select query on campaign1 to count number of records.
What i'm doing right now is .
-Select from campign_list
-loop through all campaign_table_names and run select query individually
Is there a way to do this using a single query
something like this
select campaign_name,(SELECT COUNT(*) FROM c.campaign_name) as campcount from campaign_list c
SQLFiddle : http://sqlfiddle.com/#!9/b766d/2
It's not possible inside a single query to build it dynamically but it's possible to cheat. Especially if there are only two linked tables.
I've listed two options
left outer join both tables
select campaign_name,
coalesce(c1.campaign_details, c2.campaign_details)
from campaign_list c
left join campaign1 c1 using (id)
left join campaign2 c2 using (id);
union all two different selects
select campaign_name,
campaign_details
from campaign_list c
join campaign1 c1 using (id)
union all
select campaign_name,
campaign_details
from campaign_list c
join campaign2 c2 using (id);
sqlfiddle
Combine your campaign tables to 1 table and add an column named 'type' (int).
campaign_items tables:
item_id item_details item_type
1 'some detail' 1
2 'some detail' 1
3 'some other detail' 2
4 'some other detail' 2
campaign_lists table
campaign_id campaign_name
1 'campaign1'
2 'campaign2'
Then you can use the following select statement:
SELECT campaign_name, (SELECT COUNT(*) FROM campaign_items WHERE item_type = campaign_id) as campaign_count
FROM campaign_lists
Oops, writing took me so long that you got this answered by Colin Raaijmakers already. Well, I'll post my answer anyway in spite of being more or less the same answer. Maybe my elaboration helps you see the problem.
Your problem stems from a bad database design. A database is made to order data and its relations. A CD database holds albums, songs, artists, etc. A business database may hold items, warehouses, sales and so on. Your database holds table names. [... time for thinking :-) ]
(When writing a DBMS you would want to store table names, column names, constraints etc., but I guess I am right supposing that you are not writing a new DBMS.)
So create tables that deal with your actual data. E.g.:
campain_type (id_campain_type, description, ...)
campain (id_campain, id_campain_type, campain_date, ...)
campain_type
id_campain_type description
1 Type A
2 Type B
3 Type C
campain
id_campain id_campain_type date
33 1 2015-06-03
85 2 2015-10-23
97 2 2015-12-01
query
select
ct.description,
(select count(*) from campain c where c.id_campain_type = ct.id_campain_type) as cnt
from campain_type ct;
result
description cnt
Type A 1
Type B 2
Type C 0

MYSQL counting occurrences separately from 2 tables

I got 3 tables in my MYSQL bases and I have to compare how many time there are each user_ID in each of the 2 first table (table 1 and table 2)
here is my table 1:
user_ID
A
B
A
D
...
here is my table 2 :
user_ID
A
C
A
...
here is my table 3 (with link between user_ID and nickname) :
user_ID // nickname
A // Bob
B // Joe
C // Tom
...
I would like to get a result like this:
Nickname // count occurrences from Table 1 // count occurrences from table 2
Bob // 1 // 2
Joe // 4 // 0
Tom // 0 // 2
I did not succeed for instant to count separately from each table, I got a global result for each nickname :(
Could you help me to find the right MYSQL request ?
- ...
This type of query is a little tricky, because some names may not be in the first table and others may not be in the second. To really solve this type of problem, you need to pre-aggregate the results for each query. To get all the names, you need a left outer join:
select t3.name, coalesce(cnt1, 0) as cnt1, coalesce(cnt2, 0) as cnt2
from table3 t3 left outer join
(select name, count(*) as cnt1
from table1
group by name
) t1n
on t3.name = t1n.name left outer join
(select name, count(*) as cnt2
from table2
group by name
) t2n
on t3.name = t1n.name;

Identifying groups in Group By

I am running a complicated group by statement and I get all my results in their respective groups. But I want to create a custom column with their "group id". Essentially all the items that are grouped together would share an ID.
This is what I get:
partID | Description
-------+---------+--
11000 | "Oven"
12000 | "Oven"
13000 | "Stove"
13020 | "Stove"
12012 | "Grill"
This is what I want:
partID | Description | GroupID
-------+-------------+----------
11000 | "Oven" | 1
12000 | "Oven" | 1
13000 | "Stove" | 2
13020 | "Stove" | 2
12012 | "Grill" | 3
"GroupID" does not exist as data in any of the tables, it would be a custom generated column (alias) that would be associated to that group's key,id,index, whatever it would be called.
How would I go about doing this?
I think this is the query that returns the five rows:
select partId, Description
from part p;
Here is one way (using standard SQL) to get the groups:
select partId, Description,
(select count(distinct Description)
from part p2
where p2.Description <= p.Description
) as GroupId
from part p;
This is using a correlated subquery. The subquery is finding all the description values less than the current one -- and counting the distinct values. Note that this gives a different set of values from the ones in the OP. These will be alphabetically assigned rather than assigned by first encounter in the data. If that is important, the OP should add that into the question. Based on the question, the particular ordering did not seem important.
Here's one way to get it:
SELECT p.partID,p.Description,b.groupID
FROM (
SELECT Description,#rn := #rn + 1 AS groupID
FROM (
SELECT distinct description
FROM part,(SELECT #rn:= 0) c
) a
) b
INNER JOIN part p ON p.description = b.description;
sqlfiddle demo
This gets assigns a diferent groupID to each description, and then joins the original table by that description.
Based on your comments in response to Gordon's answer, I think what you need is a derived table to generate your groupids, like so:
select
t1.description,
#cntr := #cntr + 1 as GroupID
FROM
(select distinct table1.description from table1) t1
cross join
(select #cntr:=0) t2
which will give you:
DESCRIPTION GROUPID
Oven 1
Stove 2
Grill 3
Then you can use that in your original query, joining on description:
select
t1.partid,
t1.description,
t2.GroupID
from
table1 t1
inner join
(
select
t1.description,
#cntr := #cntr + 1 as GroupID
FROM
(select distinct table1.description from table1) t1
cross join
(select #cntr:=0) t2
) t2
on t1.description = t2.description
SQL Fiddle
SELECT partID , Description, #s:=#s+1 GroupID
FROM part, (SELECT #s:= 0) AS s
GROUP BY Description

How to query multiple rows from EAV table design?

I have a situation where I have to use EAV table design.
I have the following two tables.
Nodes
id name structure_id
1 name 1 7
2 name 2 7
Attributes
id node_id name value structure_id
1 1 firstname test 7
2 1 lastname test 7
3 2 firstname test 7
I have the following query
SELECT n.*, GROUP_CONCAT( CONCAT_WS('||', a.name, a.value) ORDER BY a.name SEPARATOR ';;' ) as _attributes
FROM nodes n JOIN attributes a ON n.structure_id = a.structure_id where n.structure_id = 7
The above query outputs the following (only ONE row)
id: 1
name: name 1
structure_id: 7
_attributes: firstname||test;;firstname||test;;firstname||test;;firstname||test;;lastname||test;;lastname||test
How do I make it to output two rows from nodes table with their rows from attributes?
You will obtain desired result set if join nodes and attributes tables by structure_id and node_id.
Desired result set: "from nodes table with their rows from attributes" .
http://sqlfiddle.com/#!2/83643/1
Good luck
select n.id,n.name,n.structure_id,firstname,lastname from Nodes n
join (select node_id, a.value as firstname from Attributes a where a.name='firstname' ) matches1 on matches1.node_id = n.id
left join (select node_id, a.value as lastname from Attributes a where a.name='lastname' ) matches2 on matches2.node_id = n.id

MySQL case-when-then (or other ways) to check values of multiple rows

I request some help with MySQL when-then statement to fetch all the sid from the table after comparing multiple records having same sid but different cid-data values:
flag sid cid data
---- --- --- ----
1 300 1 john
1 300 2 john_email
1 300 3 77500
1 300 4 ok
1 301 1 jack
1 301 2 john_email
1 301 3 72210
1 301 4 notok
Here for each sid, I need to check if (sid=2 has data=john_email) AND (sid=4 has data=ok)
Only if both the conditions are satisfied, I return the sid. i.e. the output will be '300' only.
I am confused how to use the case-when-then and compare 'data' with 'john_email' and also compare data with 'ok' ... based on the cid values. Thanks for reading.
try
select sid
from your_table
group by sid
where (cid=2 and data='john_email')
or (cid=4 and data='ok')
having sum(cid=2)=1 and sum(data='john_email')=1
and sum(cid=4)=1 and sum(data='ok')=1
SQLFiddle example
You should join the table to itself, then you can check the condition in the two rows as if it was one row...
SELECT T1.sid
FROM MYTABLE T1
JOIN MYTABLE T2 ON T1.SID=T2.SID AND T1.CID=1 AND T2.CID=4
WHERE T1.DATA='john'
AND T2.DATA='ok'
Note that I used the CID values in the join clause, but you will have to adjust them if you want to join on different data rows...
What you can do is use a subquery and check if the value exists.
SELECT
*
FROM
table outertable
WHERE
( cid=2 AND data='john_email' )
AND
EXISTS ( SELECT sid FROM table WHERE cid = 4 AND data = 'ok' AND sid = outertable.sid )