I'm looking for a way to SELECT this result:
id_item name1 name2 name3
1 value10 value20 value30
2 - value40 -
3 value50 value60 -
From this DB table (here's custom fields to each id_item):
id_item Name Value
1 name1 value10
1 name2 value20
1 name3 value30
2 name2 value40
3 name1 value50
3 name2 value60
Can't solve it. Is there a way?
You can get your new result with this query:
SELECT
id_item,
MAX(CASE WHEN Name = 'name1' THEN value ELSE '-' END) name1,
MAX(CASE WHEN Name = 'name2' THEN value ELSE '-' END) name2,
MAX(CASE WHEN Name = 'name3' THEN value ELSE '-' END) name3
FROM
your_table
GROUP BY
id_item;
Demo
I adapted this great answer of bluefeet to generate this query dynamically:
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
'MAX(CASE WHEN e.Name = ''',
e.Name,
''' THEN value ELSE ''-'' END) AS ',
e.Name
) INTO #sql
FROM example e;
SET #sql = CONCAT('SELECT e.id_item
, ', #sql, '
from example e
GROUP BY e.id_item;');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
Demo
I think You will need to develop store procedure.
Step 1 : find distinct value of 'Name' Column and store in any session variable
Step 2: use while loop and generate dynamic query
Example:
select * from (select A.id_item,if(A.Name='name1',A.Value,Null) as 'name1',if(A.Name='name2',A.Value,Null) as 'name2',if(A.Name='name3',A.Value,Null) as 'name3' from testtable A) group by id_item
I hope you get my explanation
If you have any query then comment here then I can build example in sql fiddle if needed.
Related
I'm still having some troubles to understand pivoted tables, but I managed to do this working query:
select region,
sum(case when rescheduleCause = 'CLOSED' then round(reschedulePercentage,2) end) as 'CLOSED',
sum(case when rescheduleCause = 'RESHUFFLE' then round(reschedulePercentage,2) end) as 'RESHUFFLE',
sum(case when rescheduleCause = 'NEW PRIORITY' then round(reschedulePercentage,2) end) as 'NEW PRIORITY'
from fancy_table
group by region
I'm getting the following result which calculations are correct:
region | CLOSED | RESHUFFLE | NEW PRIORITY
___________________________________________
RegionA | 23.08 | NULL | 38.46
RegiobB | 23.08 | NULL | 7.69
My problem in that RESHUFFLE column full of NULL values. My desired result set would look like this:
region | CLOSED | NEW PRIORITY
___________________________________________
RegionA | 23.08 | 38.46
RegiobB | 23.08 | 7.69
I know this can be achieved if I modify this query into a stored procedure using a dynamic sql, but the columns I need are as limitated as these ones, so I think it's not really that necessary. I've tried:
ifnull(sum(case when rescheduleCause = 'RESHUFFLE' then round(reschedulePercentage,2) end),0) as 'RESHUFFLE',
where `RESHUFFLE` is not null
where 'RESHUFFLE' is not null
having `RESHUFFLE` is not null
I'm out of ideas.
When you are querying in SQL you need to know the number of columns ahead of time, you can't just exclude columns on the fly. If you are going to have an unknown number of columns, then you'll need to use dynamic SQL to first create a sql string that will be executed.
In MySQL this can be done using prepared statements. This will first query your table to only return the rescheduleCause values that you actually have. These values are concatenated together into a sql string, then you'll use this string to create your final query to be executed:
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'sum(case when rescheduleCause = ''',
rescheduleCause,
''' then round(reschedulePercentage,2) end) AS ',
replace(rescheduleCause, ' ', '')
)
) INTO #sql
from fancy_table;
SET #sql = CONCAT('SELECT region, ', #sql, '
from fancy_table
group by region');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
See SQL Fiddle with Demo
I have a database (MySQL 5.5) similar to this:
ID Name Page Visited Date
1 Tim Page A 11-2-2000
1 Tim Page B 11-3-2000
1 Tim Page B 11-3-2000
2 Jeff Page C 11-5-2000
2 Jeff Page A 11-11-2000
I want to build a query (trying to at the moment), where the results would be similar to this:
ID Name Page A Visits Page B Visits Page C Visits
1 Tim 1 2 0
I assume that I need to run the following query against a subset (my question is how do I do this with essentially 3 counts)?:
SELECT * From database.mytable GROUP BY ID HAVING COUNT(*) >=1
SELECT ID, Name,
SUM(CASE WHEN `Page Visited` = 'Page A' THEN 1 ELSE 0 END) `Page A Visit`,
SUM(CASE WHEN `Page Visited` = 'Page B' THEN 1 ELSE 0 END) `Page B Visit`,
SUM(CASE WHEN `Page Visited` = 'Page C' THEN 1 ELSE 0 END) `Page C Visit`
FROM tableName
GROUP BY ID, Name
SQLFiddle Demo
if you have unknown number of page, you can also PreparedStatement
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'SUM(CASE WHEN `Page Visited` =''',
`Page Visited`,
''' then 1 ELSE 0 end) AS ',
CONCAT('`',`Page Visited`, ' Visits`')
)
) INTO #sql
FROM TableName;
SET #sql = CONCAT('SELECT ID, Name, ', #sql, '
FROM tableName
GROUP BY ID, Name');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SQLFiddle Demo
I have the following table:
----------------------------------------------
|ID|Vote_Item_ID|User_ID|Country_code| Vote|
|01| 105102151|user1 | CA| like|
|02| 105102151|user2 | CA|dislike|
|03| 105102151|user3 | UK|dislike|
|04| 105102151|user4 | UK| like|
|05| 105102151|user5 | UK| like|
----------------------------------------------
What I need to do is create an SQL statement that creates an array which totals the likes and dislikes for each country...The script I am using this with has 175 countries, so would this be an inefficient way to about it?
I'm not sure how to go about writing the Select statement, since I want the script to be reusable for many different "vote_item_id"s
I am using PDO with a MYSQL database by the way.
Thanks
SELECT Country_Code,
SUM(CASE WHEN vote = 'like' THEN 1 ELSE 0 END) `like`,
SUM(CASE WHEN vote = 'dislike' THEN 1 ELSE 0 END) dislike
FROM tableName
GROUP BY Country_Code
SQLFiddle Demo
or if you want PreparedStatement (both give the same results)
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'SUM(CASE WHEN vote = ''',
Vote,
''' then 1 Else 0 end) AS `',
Vote, '`'
)
) INTO #sql
FROM TableName;
SET #sql = CONCAT('SELECT Country_Code, ', #sql, '
FROM tableName
GROUP BY Country_Code');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SQLFiddle Demo
If you had shown your expected output, that would have been great.
Following sample is simple. So let us know what you really need beyond this. Would be happy to pitch in. :)
REFERENCE : SQLFIDDLE
CODE:
SELECT t.country_code,
sum(CASE WHEN t.vote = 'like'
THEN 1 ELSE 0 END) AS LIKES,
sum(CASE WHEN t.vote = 'dislike'
THEN 1 ELSE 0 END) AS DISLIKE
FROM tbl t
GROUP BY t.country_code
;
RESULTS:
COUNTRY_CODE LIKES DISLIKE
CA 1 1
UK 2 1
i have one table with a single column having three values a,b and c.
Current snapshot of the table is
Table name:- tblTest
Values
tblColumn
a
a
a
b
b
b
b
c
c
i need to get the output exactly as
A B C
3 4 2
select sum(tblColumn = 'a') as A,
sum(tblColumn = 'b') as B,
sum(tblColumn = 'b') as C
from tblTest
SQL Fiddle Example
SELECT SUM(CASE WHEN colName = 'a' THEN 1 ELSE 0 END) as A,
SUM(CASE WHEN colName = 'b' THEN 1 ELSE 0 END) as B,
SUM(CASE WHEN colName = 'c' THEN 1 ELSE 0 END) as C
FROM tableName
another technique is by using PreparedStatement, this is very good if you have multiple unknown number group of values, eg, a,b,c,d,e,f,g,h,...
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'SUM(IF(tblColumn = ''',
tblColumn,
''', 1, 0)) AS ',
tblColumn
)
) INTO #sql
FROM
Table1;
SET #sql = CONCAT('SELECT ', #sql, ' FROM Table1');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SQLFiddle Demo
Try this
select tblColumn, Count(*) from tblTest group by tblColumn
How do i return multiple columns from a table ?
My Course table:
| Course | PersId | Taskid | Status |
Computer < > User1 <> 1 < > confirmed
Computer < >User2 <> 1 <> unconfirmed
Computer < >User3 <> 1 <> unconfirmed
Computer < >User1 <> 2 <> confirmed
Computer < >User2 <> 2 <> confirmed
Computer < >User3 <> 2 <> unconfirmed
I want it to return like this:
| PersId | Task_1 | Task_2 |
User1 <> confirmed < > confirmed
User2 <> unconfirmed <> confirmed
User3 <> unconfirmed <> unconfirmed
Question 2: There are other courses(math, english etc) in my table with more tasks than two. Do i need to use some kind of iteration to return the task columns ? because i dont want to make a SQL query for each single course(over 100).
thanks in advance
You can use a CASE and an aggregate:
select persid,
max(case when taskid = 1 then status end) as Task1,
max(case when taskid = 2 then status end) as Task2
from course
group by persid
If you want to include the course info:
select persid,
course,
max(case when taskid = '1' then status end) as Task1,
max(case when taskid = '2' then status end) as Task2
from course
group by persid, course
order by course, persid
See SQL Fiddle with Demo
If you have an unknown number of tasks, then you can use a prepared statement to generate this dynamically:
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'max(case when taskid = ''',
taskid,
''' then status end) AS Task_',
taskid
)
) INTO #sql
FROM course;
SET #sql = CONCAT('SELECT persid, course, ', #sql, '
FROM course
group by persid, course
order by course, persid');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
See SQL Fiddle with Demo
Like this:
SELECT
PersId,
MAX(CASE WHEN Taskid = 1 THEN Status END) AS Task_1,
MAX(CASE WHEN Taskid = 2 THEN Status END) AS Task_2
FROM Courses
GROUP BY persID
Use power of PIVOTE man
PIVOT rotates a table-valued expression by turning the unique values from one column in the expression into multiple columns in the output, and performs aggregations where they are required on any remaining column values that are wanted in the final output.
SELECT Course, PersId, [1] AS [Task_1], [2] AS [Task_2]
FROM
(
SELECT Course, PersId, TaskId, [Status]
FROM t2
) as a
PIVOT
(
MAX([Status])
FOR TaskId IN ([1], [2])
) as b