I want to count all entries in one table grouped by the user id.
This is the query I used which works fine.
select uuid_mapping_id, count(*) from t_message group by uuid_mapping_id;
and these are the results:
+-----------------+----------+
| uuid_mapping_id | count(*) |
+-----------------+----------+
| 1 | 65 |
| 4 | 277 |
Now I would like to display the actual user name, instead of the ID.
To achieve this I would need the help of two different tables.
The table t_uuid_mapping which has two columns:
uid_mapping_id, which equals uuid_mapping_id in the other table.
And f_uuid which is also unique but completely different.
f_uuid can also be found in another table t_abook which also contains the names in the column f_name.
The result I am looking for should be:
+-----------------+----------+
| f_name | count(*) |
+-----------------+----------+
| admin | 65 |
| user1 | 277 |
I am new to the database topic and understand that this could be achieved by using JOIN in the query, but to be honest I did not completely understand this yet.
if I understand you correctly:
SELECT tm.f_name, COUNT(*) as count
FROM t_message tm
LEFT JOIN t_abook ta ON (tm.uuid_mapping_id = ta.uid_mapping_id)
GROUP BY tm.f_name
Related
I have a record table and its comment table, like:
| commentId | relatedRecordId | isRead |
|-----------+-----------------+--------|
| 1 | 1 | TRUE |
| 2 | 1 | FALSE |
| 3 | 1 | FALSE |
Now I want to select newCommentCount and allCommentCount as a server response to the browser. Is there any way to select these two fields in one SQL?
I've tried this:
SELECT `isRead`, count(*) AS cnt FROM comment WHERE relatedRecordId=1 GROUP BY `isRead`
| isRead | cnt |
| FALSE | 2 |
| TRUE | 1 |
But, I have to use a special data structure to map it and sum the cnt fields in two rows to get allCommentCount by using an upper-layer programming language. I want to know if I could get the following format of data by SQL only and in one step:
| newCommentCount | allCommentCount |
|-----------------+-----------------|
| 2 | 3 |
I don't even know how to describe the question. So I got no any search result in Google and Stackoverflow. (Because of My poor English, maybe)
Use conditional aggregation:
SELECT SUM(NOT isRead) AS newCommentCount, COUNT(*) AS allCommentCount
FROM comment
WHERE relatedRecordId = 1;
if I under stand you want show sum of newComments Count and all comments so you can do it like
SELECT SUM ( CASE WHEN isRead=false THEN 1 ELSE 0 END ) AS newComment,
Count(*) AS AllComments From comments where relatedRecord=1
also you can make store procedure for it.
To place two result sets horizontally, you can as simple as use a subquery for an expression in the SELECT CLAUSE as long as the number of rows from the result sets match:
select (select count(*) from c_table where isread=false and relatedRecordId=1 ) as newCommentCount,
count(*) as allCommentCount
from c_table where relatedRecordId=1;
So I have the following key/value pair table, where users submit data through a form and each question on the form is added to the table here as an individual row. Submission_id identifies each form submission.
+----+---------------+--------------+--------+
| id | submission_id | key | value |
+----+---------------+--------------+--------+
| 1 | 10 | manufacturer | Apple |
| 2 | 10 | model | 5s |
| 3 | 10 | firstname | Paul |
| 4 | 15 | manufacturer | Apple |
| 5 | 15 | model | 5s |
| 6 | 15 | firstname | Paul |
| 7 | 20 | manufacturer | Apple |
| 8 | 20 | model | 5s |
| 9 | 20 | firstname | Andrew |
+----+---------------+--------------+--------+
From the data above you can see that the submissions with id of 10 and 15 both have the same values (just different submission id). This is basically because a user has submitted the same form twice and so is a duplicate.
Im trying to find a way to order these table where the any duplicate submissions appear together in order. Given the above table I am trying to build a query that gives me the result as below:
+---------------+
| submission_id |
+---------------+
| 10 |
| 15 |
| 20 |
+---------------+
So I want to check to see if a submission where the manufacturer, model and firstname keys have the same value. If it does then these get the submission id and place them adjacently in the result. In the actual table there are other keys, but I only want to match duplicates based on these 3 keys (manufacturer, model, firstname).
I’ve been going back and forth to the drawing board quite some time now and have tried looking for some possible solutions but cannot get something reliable.
That's not a key value table. It's usually called an Entity-Attribute-Value table/relation/pattern.
Looking at the problem, it would be trivial if the table were laid out in conventional 1st + 2nd Normal form - you just do a join on the values, group by those and take a count....
SELECT manufacturer, model, firstname, COUNT(DISTINCT submission_id)
FROM atable
GROUP BY manufacturer, model, firstname
HAVING COUNT(DISTINCT submission_id)>1;
Or a join....
SELECT a.manufacturer, a.model, a.firstname
, a.submission_id, b.submission_id
FROM atable a
JOIN atable b
ON a.manufacturer=b.manufacturer
AND a.model=b.model
AND a.firstname=b.firstname
WHERE a.submission_id<b.submission_id
;
Or using sorting and comparing adjacent rows....
SELECT *
FROM
(
SELECT #prev.submission_id AS prev_submission_id
, #prev.manufacturer AS prev_manufacturer
, #prev.model AS prev_model
, #prev.firstname AS pref_firstname
, a.submission_id
, a.manufacturer
, a.model
, set #prev.submission_id:=a.submission_id as currsid
, set #prev.manufacturer:=a.manufacturer as currman
, set #prev.model:=a.model as currmodel
, set #prev.firstname=a.forstname as currname
FROM atable
ORDER BY manufacturer, model, firstname, submission_id
)
WHERE prev_manufacturer=manufacturer
AND prev_model=model
AND prev_firstname=firstname
AND prev_submission_id<>submission_id;
So the solution is to simply make your data look like a normal relation....
SELECT ilv.values
, COUNT(ilv.submission_id)
, GROUP_CONCAT(ilv.submission_id)
FROM
(SELECT a.submission_id
, GROUP_CONCAT(CONCAT(a.key, '=',a.value)) AS values
FROM atable a
GROUP BY a.submission_id
) ilv
GROUP BY ilv.values
HAVING COUNT(ilv.submission_id)>1;
Hopefully the join and sequence based solutions should now be obvious.
I have a table of tickets to multiple dates of shows shows. basically, it looks like this...
+----+---------------+--------------+-----------+
| ID | ticket_holder | ticket_buyer | show_date |
+----+---------------+--------------+-----------+
ticket_holder and ticket_buyer are both user ids
If I wanted to count the total number of tickets that one ticket holder has, I could group by that holder and count the rows, but I want more stats than that.
I want to know a user's total bought tickets, how many they hold and how many shows they've bought tickets for.
+------+---------+--------+-------+
| USER | HOLDING | BOUGHT | DATES |
+------+---------+--------+-------+
| 1 | 12 | 24 | 7 |
+------+---------+--------+-------+
| 2 | 3 | 4 | 2 |
+------+---------+--------+-------+
| 3 | 1 | 2 | 1 |
+------+---------+--------+-------+
is it possible to put all this in a query, or do i need to do php stuff to make it happen?
I would do it in multiple queries. You can't group by either ticket_holder or ticket_buyer like you want, in a single query. If you try GROUP BY ticket_holder, ticket_buyer then it will group by both columns, which is not what you want.
SELECT ticket_holder, COUNT(*) AS tickets_held
FROM `a table of tickets` GROUP BY ticket_holder;
SELECT ticket_buyer, COUNT(*) as tickets_bought
FROM `a table of tickets` GROUP BY ticket_buyer;
SELECT ticket_buyer, COUNT(DISTINCT show_date) AS shows_bought
FROM `a table of tickets` GROUP BY ticket_buyer;
Not every task has to be accomplished in a single query! It's part of the design of SQL that it should be used by some application language, and you're expected to handle formatting and display in the application.
I am having some difficulties to accomplish a task.
Here is some data from orders table:
+----+---------+
| id | bill_id |
+----+---------+
| 3 | 1 |
| 9 | 3 |
| 10 | 4 |
| 15 | 6 |
+----+---------+
And here is some data from a bills table:
+----+
| id |
+----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
+----+
I want to list all the bills that have no order associated with.
In order to achieve that, I thought that the use of LEFT JOIN was appropriated so I wrote this request:
SELECT * FROM bills
LEFT JOIN orders
ON bills.id = orders.bill_id
WHERE orders.bill_id IS NULL;
I thought that I would have the following result:
+----------+-----------+----------------+
| bills.id | orders.id | orders.bill_id |
+----------+-----------+----------------+
| 2 | NULL | NULL |
| 5 | NULL | NULL |
+----------+-----------+----------------+
But I can't reach the end of the request, it has run more than 5 minutes without result, I stopped the request because this can't be a production time anyway.
My real dataset has more than 150 000 orders and 100 000 bills. Is the dataset too big?
Is my request wrong somewhere?
Thank you very much for your tips!
EDIT: side note, the tables have no foreign keys defined... *flies away*
Your query is fine. I would use table aliases in writing it:
SELECT b.*
FROM bills b LEFT JOIN
orders o
ON b.id = o.bill_id
WHERE o.bill_id IS NULL;
You don't need the NULL columns from orders, probably.
You need an index on orders(bill_id):
create index idx_orders_billid on orders(bill_id);
By your where statement, I assume your looking for orders that have no bills.
If that's the case you don't need to do a join to the bills table as they would by definition not exist.
You will find
SELECT * FROM orders
WHERE orders.bill_id IS NULL;
A much better performing query.
Edit:
Sorry I missed your "I want to list all the bills that have no order associated with." when reading the question. As #gordon pointed out an index would certainly help. However if changing the scheme is feasible I would rather have a nullable bill.order_id column instead of a order.bill_id because you won't need a left join, an inner join would suffice to get order bills as it would be a quicker query for your other assumed requirements.
i have two tables named as oc_users and oc_groups there is no specific relation between both the tables as shown below so, here i want to map each user with each group:
1)table 1:
select uid from oc_users;
+-----------------+
| uid |
+-----------------+
| manesh#abc.in |
| pankaj |
| sumit |
+-----------------+
2)table 2:
select gid from oc_groups;
+---------+
| gid |
+---------+
| qlc |
| qlc-web |
+---------+
Then i want o/p like:
+---------+-----------------+
| gid | uid |
+---------+-----------------+
| qlc | manesh#abc.in |
| qlc | pankaj |
| qlc | sumit |
| qlc-web | manesh#abc.in |
| qlc-web | pankaj |
| qlc-web | sumit |
+---------+-----------------+
Use this
select * from oc_user , oc_groups ORDER BY gid, uidS
This will print all columns with Cartesian multiplecation of rows.
you need to use CROSS JOIN (new SQL Syntax: ANSI SQL-92)
SELECT gid, uid
FROM oc_users CROSS JOIN oc_groups
ORDER BY gid, uid
SQLFiddle Demo
Using CROSS JOIN(Cartesian Product Join) will solve your purpose. For your information
A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table.
So simply this will do,
SELECT gid, uid
FROM oc_users CROSS JOIN oc_groups;
Always go for 'CROSS JOIN' syntax instead of giving nothing. Since this is ANSI format you can use it across database and it will be useful during migration also as you dont need to change anything in your query.
Hope this helps you!!