So lets say we have the following table of data:
A | B
_________
1 | 2
3 | 4
5 | 6
6 | 5
And what if I wanted to count the times the same numbers collide or are in the same line? So in the above example 1-2 and 3-4 would return a count of one because they are on the same line only once however 5-6 and 6-5 would return a value of 2.
A more real life illustration: think that the numbers are sport team id's and the A and B columns determine the host-team and the guest-team. Ao teams 5 and 6 have played a total of 2 games against each other, first team 5 as a host and then team 6 as a host.
So how could I count these in mysql?
DROP TABLE IF EXISTS fixtures;
CREATE TABLE fixtures
(fixture_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,home INT NOT NULL
,away INT NOT NULL
);
INSERT INTO fixtures (home,away) VALUES (1,2),(3,4),(5,6),(6,5);
SELECT * FROM fixtures;
+------------+------+------+
| fixture_id | home | away |
+------------+------+------+
| 1 | 1 | 2 |
| 2 | 3 | 4 |
| 3 | 5 | 6 |
| 4 | 6 | 5 |
+------------+------+------+
SELECT LEAST(home,away) a,GREATEST(home,away) b, COUNT(*) ttl FROM fixtures GROUP BY a,b;
+---+---+-----+
| a | b | ttl |
+---+---+-----+
| 1 | 2 | 1 |
| 3 | 4 | 1 |
| 5 | 6 | 2 |
+---+---+-----+
SELECT
CASE WHEN A < B THEN A ELSE B END AS aa,
CASE WHEN B > A THEN B ELSE A END AS bb,
COUNT(*)
FROM
Table1 t1
GROUP BY aa, bb
See it live in an sqlfiddle.
As a-b is the same as b-a, you want to normalize that result:
SELECT LEAST(a,b) AS x, GREATEST(a,b) AS y ...
Now you can count the occurences:
SELECT LEAST(a,b) AS x, GREATEST(a,b) AS y, count(*) as c FROM tablename GROUP BY x,y
Greets
Related
I have a table. It has a pk of id and an index of [service, check, datetime].
id service check datetime score
---|-------|-------|----------|-----
1 | 1 | 4 |4/03/2009 | 399
2 | 2 | 4 |4/03/2009 | 522
3 | 1 | 5 |4/03/2009 | 244
4 | 2 | 5 |4/03/2009 | 555
5 | 1 | 4 |4/04/2009 | 111
6 | 2 | 4 |4/04/2009 | 322
7 | 1 | 5 |4/05/2009 | 455
8 | 2 | 5 |4/05/2009 | 675
Given a service 2 I need to select the rows for each unique check where it has the max date. So my result would look like this table.
id service check datetime score
---|-------|-------|----------|-----
6 | 2 | 4 |4/04/2009 | 322
8 | 2 | 5 |4/05/2009 | 675
Is there a short query for this? The best I have is this, but it returns too many checks. I just need the unique checks at it's latest datetime.
SELECT * FROM table where service=?;
First you need find out the biggest date for each check
SELECT `check`, MAX(`datetime`)
FROM YourTable
WHERE `service` = 2
GROUP BY `check`
Then join back to get the rest of the data.
SELECT Y.*
FROM YourTable Y
JOIN ( SELECT `check`, MAX(`datetime`) as m_date
FROM YourTable
WHERE `service` = 2
GROUP BY check) as `filter`
ON Y.`service` = `filter`.service
AND Y.`datetime` = `fiter`.m_date
WHERE Y.`service` = 2
I have two tables.
1) jb_theme_metadata
column : idx | t_name
1 | sports
2 | movies
2) jb_theme
column : idx | theme_idx(F key of jb_theme_metadata) | u_idx (F key of jb_user)
1 | 1 | 3
2 | 1 | 4
3 | 1 | 5
4 | 2 | 7
expected output
column : idx | t_name | user_count
1 | sports | 3
2 | moives | 1
Can I make this output by a sql query not two statements?
May be this would work for you:
SELECT m.idx, m.t_name, COUNT(t.u_idx) as user_count
FROM jb_theme_metadata AS m
JOIN jb_theme AS t ON t.theme_idx=m.idx
GROUP BY t.theme_idx
I have 2 tables, the first table or_f_table data. The second table or_table
or_f_table
f_id | f_o_id | f_u_id
1 | 19 | 1
2 | 5 | 2
3 | 19 | 2
or_table
o_id | o_name
4 | test1
5 | test2
19 | oops2
20 | oops3
SELECT o.o_name,
IF ((SELECT count(*) FROM or_f_table as f
WHERE f.f_u_id = 1 ),'Yes','No') as follow_status
FROM or_table as o
WHERE o.o_name LIKE '%oop%'
I want to do something like this result :-
o_name | follow_status
oops2 | Yes
oops3 | No
I am getting result
o_name | follow_status
oops2 | Yes
oops3 | Yes
Why doesn't it work? And how should I correct it
There will always be a value greater than 0 for your where condition. That is why it is not working.
Try this to get the specified results
SELECT o.o_name,
IF ((SELECT count(*) FROM or_f_table as f
WHERE f.f_o_id = o.o_id ),'Yes','No') as follow_status
FROM or_table as o
WHERE o.o_name LIKE '%oop%'
I have a table (innoDB) that has 3 columns: ID, ID_FATHER, ROWPOS. ID is auto_increment and ROWPOS has values from other table. I need ID_FATHER to be incremented by 1 if ROWPOS is not a sequence, if it is a sequence ID_FATHER should not increment.
Like this:
ID | ID_FATHER | ROWPOS
1 | 1 | 250
2 | 2 | 253
3 | 2 | 254
4 | 3 | 260
5 | 4 | 263
6 | 5 | 268
7 | 6 | 270
8 | 6 | 271
9 | 6 | 272
10 | 7 | 276
Is there a way to do that?
With this query:
INSERT INTO mytable (i, rowpos)
SELECT #i := IF(t.rowpos = #prev_rowpos + 1, #i, #i + 1) AS i
, #prev_rowpos := t.rowpos AS rowpos
FROM temp
JOIN (SELECT #prev_rowpos := NULL, #i := 0) v
ORDER BY t.rowpos
I am able to import into the tables I want. But the problem is in the TABLE.Service, as you can see with this solution the ID_FATHER is wrong because it only increments by 1
but in this case it actually should be 2 because invoice 1 doesn't have service.
How can I solve this problem without changing all my schema.
TABLE.temp
ROW|TYPE |INVOICE_temp
1 |xxx |10
2 |xxP |led tv
3 |xxP |mp3 Player
4 |xxx |11
5 |xxP |tv cable
6 |xxS |install
xxx = Invoice number
xxP = Product
xxs = service
TABLE.Invoice_Number TABLE.Product
ID|ID_FATHER|ROWPOS|NUM ID|ID_FATHER|ROWPOS|PROD
1 | 1 | 1 | 10 1 | 1 | 2 | led tv
2 | 2 | 4 | 11 2 | 1 | 3 | mp3 player
3 | 2 | 5 | tv cable
TABLE.Service
ID|ID_FATHER|ROWPOS|SERV
1 | 1 | 6 | install
I made some changes in the query to work as I needed.
You could do something like this:
INSERT INTO mytable (i, rowpos)
SELECT #i := IF(t.rowpos = #prev_rowpos + 1, #i, #i + 1) AS i
, #prev_rowpos := t.rowpos AS rowpos
FROM another_table t
JOIN (SELECT #prev_rowpos := NULL, #i := 0) v
ORDER BY t.rowpos
(Test just the SELECT query, get that working returning the resultset you want, before you preface it with the INSERT.)
For completeness, I will add that this technique is dependent on UNDOCUMENTED and non-guaranteed behavior in MysQL, using "user variables". I've successfully used this approach many times, but for "one off" type admin functions, not ever embedded as SQL in an application.
Note that the ORDER of the expressions in the SELECT list is important, they are evaluated in the order they appear in the SELECT list. (MySQL doesn't guarantee this behavior, but we do observe it. It's important that the check of the user variables containing values from the previous row to precede the assignment of the current row values to the user variables. That's why i is returned first, followed by rowpos. If you reversed the order of those in the SELECT list, the query would operate differently, and we wouldn't get the same results.
The purpose of the inline view (aliased as v) is to initialize the user variables. Since MySQL materializes that view query into a "derived table" before the outer query runs, those variables get initialized before they are referenced in the outer query. We don't really care what the inline view query actually returns, except that we need it to return exactly one row (because we reference it in a JOIN operation to the table we really want to query).
E.g.:
DROP TABLE IF EXISTS my_table;
CREATE TABLE my_table
(id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,rowpos INT NOT NULL
);
INSERT INTO my_table (rowpos) VALUES
(250),
(253),
(254),
(260),
(263),
(268),
(270),
(271),
(272),
(276);
SELECT x.*
, #i:=#i+ISNULL(y.id) i
FROM my_table x
LEFT
JOIN my_table y
ON y.id < x.id
AND y.rowpos = x.rowpos - 1
, (SELECT #i:=0) vals
ORDER
BY x.id;
+----+--------+------+
| id | rowpos | i |
+----+--------+------+
| 1 | 250 | 1 |
| 2 | 253 | 2 |
| 3 | 254 | 2 |
| 4 | 260 | 3 |
| 5 | 263 | 4 |
| 6 | 268 | 5 |
| 7 | 270 | 6 |
| 8 | 271 | 6 |
| 9 | 272 | 6 |
| 10 | 276 | 7 |
+----+--------+------+
id | userid | total_points_spent
1 | 1 | 10
2 | 2 | 15
3 | 2 | 50
4 | 3 | 5
5 | 1 | 15
With the above table, I would first like to remove duplicates of userid keeping the rows with the largest total_points_spent, like so:
id | userid | total_points_spent
3 | 2 | 50
4 | 3 | 5
5 | 1 | 15
And then I would like to sum the values of total_points_spent, which would be the easy part, resulting in 70.
I am not really sure the "remove" you meant is to delete or to select. Here is the query for select only max totalpointspend record respectively.
SELECT tblA.*
FROM ( SELECT userid, MAX(totalpointspend) AS maxtotal
FROM tblA
GROUP BY userid ) AS dt
INNER JOIN tblA
ON tblA.userid = dt.userid
AND tblA.totalpointspend = dt.maxtotal
ORDER BY tblA.userid