I want to show the number of times each distinct element in a column in a table in a SQL database appears, alongside the particular distinct element in a new output table. Is it possible in a single statement over ramming my head over it manually?
Without having actually tried, how about this:
SELECT tmp.Field, (SELECT COUNT(*) FROM [Table] t WHERE t.DesiredField = tmp.Field) AS Count
FROM
(
SELECT DISTINCT DesiredField FROM [Table]
) tmp
This would first select all distinct values from [Table] and in the outer select, take the values and the number of times they appear in the column.
You could also try
SELECT Field, SUM(1) AS Count FROM Table
GROUP BY Field
This should "flatten" the table so that it only contains distinct values in Field and the number of rows where Field has the same value.
I just tried the second - it seems to work nicely.
Turns out I was wrong all the time. The second example and the following actually return the same results:
SELECT Field, COUNT(*) AS Count FROM Table
GROUP BY Field
Simplest just to use COUNT(). You'll see varieties on what your count parameter, so here are the options.
DECLARE #tbl TABLE(id INT, data INT)
INSERT INTO #tbl VALUES (1,1),(2,1),(3,2),(4,NULL)
SELECT data
,COUNT(*) Count_star
,COUNT(id) Count_id
,COUNT(data) Count_data
,COUNT(1) Count_literal
FROM #tbl
GROUP BY data
data Count_star Count_id Count_data Count_literal
----------- ----------- ----------- ----------- -------------
NULL 1 1 0 1
1 2 2 2 2
2 1 1 1 1
Warning: Null value is eliminated by an aggregate or other SET operation.
You'll see the difference coming with the treatment of NULL if you COUNT a field that contains NULLs.
Related
I don't get where the error msg 'Illegal expression in WHEN clause of CASE expression' comes from by running this snippet in Teradata SQL
CASE
WHEN f_ev1.PROCESS_NO IN
(
SELECT
numbers.PROCESS_NO
FROM numbers
WHERE
numbers.FLAG = 1
GROUP BY 1 --no duplicates
) THEN 2
END AS Status,
If I write IN (some numbers) it works just fine. But it is a list that consists of 50 unique values that can possibly change over time.
My Suggestion is that you can load the fifty values into another table and you can join that table with the main table
table_50 - Table with 50 unique values
main_tbl - Main table
insert into table_50 ( process_no ) SELECT numbers.PROCESS_NO FROM numbers WHERE numbers.FLAG = 1 GROUP BY 1 ;
Select case when b.process_no is null then 2 end as status from main_table a
left join table_50 b
on a.process_no= b.process_no
From a performance perspective, this is more effective and you can also update the values in the table_50 as per your requirement
I have table like this :
id name qt
----------------
0 mm 4
1 mm 5
2 xx 8
I want update it or get new table that will produce this kind of result:
id name qt
------------------
0 mm 9 (sum of the two or multiple some identical )
1 xx 8
Including the id column will cause the GROUP BY to fail since multiple records are being summed that have different ids.
SELECT name, SUM(qt) as qt_sum
FROM table GROUP BY name
SELECT ROW_NUMBER() OVER (ORDER BY name) AS id
, name
, SUM(qt) AS qt
FROM YourTableName
GROUP BY name
ORDER BY name
I'm making the assumption that the id field doesn't actually mean anything because the id of the record xx actually changes between your two visuals. That's why I'm setting it by ROW_NUMBER() so it increments for distinct name. If this isn't the case, remove the ROW_NUMBER() expression and add id to the GROUP BY clause. This does mean that records in the name field may change depending on the number of distinct names.
If you really need and id column you could create one like this...
create table Test (id int, name varchar(10), qt int)
insert into Test values (0, 'mm', 4)
insert into Test values (1, 'mm', 5)
insert into Test values (2, 'xx', 8)
select
row_number() over (order by name) - 1
, name
, sum(qt) as qt
from Test
group by name
There may be some cases where this does not work for you, but with such limited sample data it is hard to tell.
I have the following table
I need to get the following output as "SVGFRAMXPOSLSVG" from the 2 columns.
Is it possible to get this appended values from 2 columns
Please try this.
SELECT STUFF((
SELECT '' + DEPART_AIRPORT_CODE + ARRIVE_AIRPORT_CODE
FROM #tblName
FOR XML PATH('')
), 1, 0, '')
For Example:-
Declare #tbl Table(
id INT ,
DEPART_AIRPORT_CODE Varchar(50),
ARRIVE_AIRPORT_CODE Varchar(50),
value varchar(50)
)
INSERT INTO #tbl VALUES(1,'g1','g2',NULL)
INSERT INTO #tbl VALUES(2,'g2','g3',NULL)
INSERT INTO #tbl VALUES(3,'g3','g1',NULL)
SELECT STUFF((
SELECT '' + DEPART_AIRPORT_CODE + ARRIVE_AIRPORT_CODE
FROM #tbl
FOR XML PATH('')
), 1, 0, '')
Summary
Use Analytic functions and listagg to get the job done.
Detail
Create two lists of code_id and code values. Match the code_id values for the same airport codes (passengers depart from the same airport they just arrived at). Using lag and lead to grab values from other rows. NULLs will exist for code_id at the start and end of the itinerary. Default the first NULL to 0, and the last NULL to be the previous code_id plus 1. A list of codes will be produced, with a matching index. Merge the lists together and remove duplicates by using a union. Finally use listagg with no delimiter to aggregate the rows onto a string value.
with codes as
(
select
nvl(lag(t1.id) over (order by t1.id),0) as code_id,
t1.depart_airport_code as code
from table1 t1
union
select
nvl(lead(t1.id) over (order by t1.id)-1,lag(t1.id) over (order by t1.id)+1) as code_id,
t1.arrive_airport_code as code
from table1 t1
)
select
listagg(c.code,'') WITHIN GROUP (ORDER BY c.code_id) as result
from codes c;
Note: This solution does rely on an integer id field being available. Otherwise the analytic functions wouldn't have a column to sort by. If id doesn't exist, then you would need to manufacture one based on another column, such as a timestamp or another identifier that ensures the rows are in the correct order.
Use row_number() over (order by myorderedidentifier) as id in a subquery or view to achieve this. Don't use rownum. It could give you unpredictable results. Without an ORDER BY clause, there is no guarantee that the same query will return the same results each time.
Output
| RESULT |
|-----------------|
| SVGFRAMXPOSLSVG |
I've looked at some answers but none of them seem to be applicable to me.
Basically I have this result set:
RowNo | Id | OrderNo |
1 101 1
2 101 10
I just want to convert this to
| Id | OrderNo_0 | OrderNo_1 |
101 1 10
I know I should probably use PIVOT. But the syntax is just not clear to me.
The order numbers are always two. To make things clearer
And if you want to use PIVOT then the following works with the data provided:
declare #Orders table (RowNo int, Id int, OrderNo int)
insert into #Orders (RowNo, Id, OrderNo)
select 1, 101, 1 union all select 2, 101, 10
select Id, [1] OrderNo_0, [2] OrderNo_1
from (
select RowNo, Id, OrderNo
from #Orders
) SourceTable
pivot (
sum(OrderNo)
for RowNo in ([1],[2])
) as PivotTable
Reference: https://learn.microsoft.com/en-us/sql/t-sql/queries/from-using-pivot-and-unpivot?view=sql-server-2017
Note: To build each row in the result set the pivot function is grouping by the columns not begin pivoted. Therefore you need an aggregate function on the column that is being pivoted. You won't notice it in this instance because you have unique rows to start with - but if you had multiple rows with the RowNo and Id you would then find the aggregation comes into play.
As you say there are only ever two order numbers per ID, you could join the results set to itself on the ID column. For the purposes of the example below, I'm assuming your results set is merely selecting from a single Orders table, but it should be easy enough to replace this with your existing query.
SELECT o1.ID, o1.OrderNo AS [OrderNo_0], o2.OrderNo AS [OrderNo_1]
FROM Orders AS o1
INNER JOIN Orders AS o2
ON (o1.ID = o2.ID AND o1.OrderNo <> o2.OrderNo)
From your sample data, simplest you can try to use min and MAX function.
SELECT Id,min(OrderNo) OrderNo_0,MAX(OrderNo) OrderNo_1
FROM T
GROUP BY Id
I like to have my query count one column two times in my select based on the value. So for example.
input: table
id | type
-------------|-------------
1 | 1
2 | 1
3 | 2
4 | 2
5 | 2
output: query (in 1 row, not two):
countfirst = 2 (two times 1)
countsecond = 3 (three times 2)
An default count in an select counts all rows in the query. But i like to count rows based
on an number without limiting the query. When using for example WHERE type = '1', type 2
gets filtered and cannot be counted anymore.
Is there an solution for this case in SQL?
--- EXAMPLE USE (situation above is simplefied but case is the same) ---
With one query i get all cars grouped by type from an table. There are two type signs: yellow (in db 1) and grey (in db 2). So in that query i have the folowing output:
Renault - ten times found - two yellow signs - eight grey signs
Create a table, script is given below.
CREATE TABLE [dbo].[temptbl](
[id] [int] NULL,
[type] [int] NULL
) ON [PRIMARY]
Execute the insert script as
insert into [temptbl] values(1,1)
insert into [temptbl] values(2,1)
insert into [temptbl] values(3,2)
insert into [temptbl] values(4,2)
insert into [temptbl] values(5,2)
Then execute the query.
;WITH cte as(
SELECT [type], Count([type]) cnt
FROM temptbl
GROUP BY [type]
)
SELECT * FROM cte
pivot (Sum([cnt]) for [type] in ([1],[2])) as AvgIncomePerDay
You can use the GROUP BY clause as Mureinik suggested, but with the addition of a WHERE clause to filter the results.
Below shows the results for type = 1 (assuming type is an INT:
SELECT type, COUNT(*) AS NoOfRecords
FROM table
WHERE type IN (1)
GROUP BY type
So if we wanted 1 and 2 we can use:
SELECT type, COUNT(*) AS NoOfRecords
FROM table
WHERE type IN (1, 2)
GROUP BY type
Lastly, that IN statement can pull type from another query:
SELECT type, COUNT(*) AS NoOfRecords
FROM table
WHERE type IN (SELECT type FROM someOtherTable)
GROUP BY type