There is some select
SELECT column1,
COUNT(CASE column2 WHEN 'type1' THEN 1 ELSE NULL END) AS Type1Count,
COUNT(CASE column2 WHEN 'type2' THEN 1 ELSE NULL END) AS Type2Count,
COUNT(CASE column2 WHEN 'type3' THEN 1 ELSE NULL END) AS Type3Count
FROM Yourtable
GROUP BY column1
help me please, how i can add column0 which values corresponds to column1 in select query, some thing like that
SELECT column0, column1,
COUNT(CASE column2 WHEN 'type1' THEN 1 ELSE NULL END) AS Type1Count,
COUNT(CASE column2 WHEN 'type2' THEN 1 ELSE NULL END) AS Type2Count,
COUNT(CASE column2 WHEN 'type3' THEN 1 ELSE NULL END) AS Type3Count
FROM Yourtable
GROUP BY column1
but my variant is not work...
When you are selecting the exact value of some columns, and aggregating (e.g. COUNT(), SUM()) on others, you need to tell the database which is which in the GROUP BY clause.
If you say:
GROUP BY column0, column1
Then for every unique combination of column0 and column1, you will get an extra row of results, with the COUNT() expressions calculated across all the rows in the table for that combination.
If you only want one row for each distinct value of column1, you need to instead tell the database which value of column0 you are interested in. For instance, you might ask for the minimum value of column0 for each column1 with this:
SELECT MIN(column0), column1 ... GROUP BY column1
Which means:
I want one row for each distinct value of ... (GROUP BY ...)
... column1 (... column1)
For each row, show me (SELECT):
The minimum value of column0 in that group
The value of column1 which will be the same for everything in that group
Related
I have two queries that give me back a single entry. How can I select both of these as on table?
query1: Select max([column3]) from [table1] => 42
query2: Select Top 1 [column1] from [table1] => 'test'
I want a resultset like this
result1
result2
42
'test'
But how to do it correctly? Can I maybe select from nowhere somehow?
You could use ROW_NUMBER, twice:
WITH cte AS (
SELECT *, ROW_NUMBER() OVER (ORDER BY column3 DESC) rn1,
ROW_NUMBER() OVER (ORDER BY some_col) rn2
FROM table1
)
SELECT MAX(CASE WHEN rn1 = 1 THEN column3 END) AS result1,
MAX(CASE WHEN rn2 = 1 THEN column1 END) AS result2
FROM cte;
Note that I assume there exists a column some_col which you intend to use for choosing the column1 value.
I have a table like this below :
Would like to change the format as below on postgres :
I tried to use the case statement but did not give me desired results.
Thank you in advance for the help !
EDIT
select (case when column_1='A' then column_1 else 'other' end) column_1,
(case when column_1='B' then Column_1 else 'other' end) column_2 from test_t
where id= random_value;
Each time the query returns only 2 rows and the row values in the column_1 are dynamic and not fixed.
Here we go...
CREATE TABLE test_table(column_1 text);
INSERT INTO test_table ('A'),('B');
SELECT * FROM test_table ;
column_1
---------
B
A
SELECT
max(case when column_1='A' THEN column_1 END) column_1,
max(case when column_1='B' THEN column_1 END) column_2
from test_table;
column_1 | column_2
----------+----------
A | B
In PostgreSQL you can do this easily with crosstab(), but in greenplum still it is not implemented
Please refer to this link. Previously answered.
stackoverflow.com/a/10625294/1870151
SELECT
unnest(array['col1', 'col2', 'col3']) AS "Columns",
unnest(array[col1::text, col2::text, col3::text]) AS "Values"
FROM tbl;
You didn't really provide enough information to really answer the question but this is how you convert those two rows from one column into two columns and forced into a single row.
select max(column_1) as column_1, max(column_2) as column_2
from (select case when column_1 = 'A' then column_1 else '' end as column_1,
case when column_1 = 'B' then column_1 else '' end as column_2
from table_name);
If the result you want to transpose always has only 2 rows, this will work regardless of the contents of those columns, as you asked:
SELECT
MAX(CASE WHEN row_number=1 THEN column_1 END) column_1,
MAX(CASE WHEN row_number=2 THEN column_1 END) column_2
FROM (SELECT column_1,
ROW_NUMBER() OVER (ORDER BY test_table.column_1)
FROM test_table) t;
column_1 | column_2
----------+----------
A | B
I've a table like this:
Source table "tab"
column1 column2
x 1
x 2
y 1
y 2
y 3
z 3
How can I build the query to get result with unique values in each of two columns separately. For example I'd like to get a result like one of these sets:
column1 column2
x 1
y 2
z 3
or
column1 column2
x 2
y 1
z 3
or ...
Thanks.
What you're asking for is difficult because it's weird: SQL treats rows as related fields but you're asking to make two separate lists (distinct values from col1 and distinct values from col2) then display them in one output table not caring how the rows match up.
You can so this by writing the SQL along those lines. Write a separate select distinct for each column, then put them together somehow. I'd put them together by giving each row in each results a row number, then joining them both to a big list of numbers.
It's not clear what you want null to mean. Does it mean there's a null in one of the columns, or that there's not the same number of distinct values in each column? This one problem from asking for things that don't match up with typical relational logic.
Here's an example, removing the null value from the data since that confuses the issue, different data values to avoid confusing rowNumber with data and so there are 3 distinct values in one column and 4 in another. This works for SQL Server, presumably there's a variation for PostgreSQL.
if object_id('mytable') is not null drop table mytable;
create table mytable ( col1 nvarchar(10) null, col2 nvarchar(10) null)
insert into mytable
select 'x', 'a'
union all select 'x', 'b'
union all select 'y', 'c'
union all select 'y', 'b'
union all select 'y', 'd'
union all select 'z', 'a'
select c1.col1, c2.col2
from
-- derived table giving distinct values of col1 and a rownumber column
( select col1
, row_number() over (order by col1) as rowNumber
from ( select distinct col1 from mytable ) x ) as c1
full outer join
-- derived table giving distinct values of col2 and a rownumber column
( select col2
, row_number() over (order by col2) as rowNumber
from ( select distinct col2 from mytable ) x ) as c2
on c1.rowNumber = c2.rowNumber
Lets say I have table with ID int, VALUE string:
ID | VALUE
1 abc
2 abc
3 def
4 abc
5 abc
6 abc
If I do select value, count(*) group by value I should get
VALUE | COUNT
abc 5
def 1
Now the tricky part, if there is count == 1 I need to get that ID from first table. Should I be using CTE? creating resultset where I will add ID string == null and run update b.ID = a.ID where count == 1 ?
Or is there another easier way?
EDIT:
I want to have result table like this:
ID VALUE count
null abc 5
3 def 1
If your ID values are unique, you can simply check to see if the max(id) = min(id). If so, then use either one, otherwise you can return null. Like this:
Select Case When Min(id) = Max(id) Then Min(id) Else Null End As Id,
Value, Count(*) As [Count]
From YourTable
Group By Value
Since you are already performing an aggregate, including the MIN and Max function is not likely to take any extra (noticeable) time. I encourage you to give this a try.
The way I would do it would indeed be a CTE:
using #group AS (SELECT value, Count(*) as count from MyTable GROUP BY value HAVING count = 1)
SELECT MyTable.ID, #group.value, #group.count from MyTable
JOIN #group ON #group.value = MyTable.value
When using group by, after the group by statement you can use a having clause.
So
SELECT [ID]
FROM table
GROUP BY [VALUE]
HAVING COUNT(*) = 1
Edit: with regards to your edited question: this uses some fun joins and unions
CREATE TABLE #table
(ID int IDENTITY,
VALUE varchar(3))
INSERT INTO #table (VALUE)
VALUES('abc'),('abc'),('def'),('abc'),('abc'),('abc')
SELECT * FROM (
SELECT Null as ID,VALUE, COUNT(*) as [Count]
FROM #table
GROUP BY VALUE
HAVING COUNT(*) > 1
UNION ALL
SELECT t.ID,t.VALUE,p.Count FROM
#table t
JOIN
(SELECT VALUE, COUNT(*) as [Count]
FROM #table
GROUP BY VALUE
HAVING COUNT(*) = 1) p
ON t.VALUE=p.VALUE
) a
DROP TABLE #table
maybe not the most efficient but something like this works:
SELECT MAX(Id) as ID,Value FROM Table WHERE COUNT(*) = 1 GROUP BY Value
My SQL is rusty -- I have a simple requirement to calculate the sum of the greater of two column values:
CREATE TABLE [dbo].[Test]
(
column1 int NOT NULL,
column2 int NOT NULL
);
insert into Test (column1, column2) values (2,3)
insert into Test (column1, column2) values (6,3)
insert into Test (column1, column2) values (4,6)
insert into Test (column1, column2) values (9,1)
insert into Test (column1, column2) values (5,8)
In the absence of the GREATEST function in SQL Server, I can get the larger of the two columns with this:
select column1, column2, (select max(c)
from (select column1 as c
union all
select column2) as cs) Greatest
from test
And I was hoping that I could simply sum them thus:
select sum((select max(c)
from (select column1 as c
union all
select column2) as cs))
from test
But no dice:
Msg 130, Level 15, State 1, Line 7
Cannot perform an aggregate function on an expression containing an aggregate or a subquery.
Is this possible in T-SQL without resorting to a procedure/temp table?
UPDATE: Eran, thanks - I used this approach. My final expression is a little more complicated, however, and I'm wondering about performance in this case:
SUM(CASE WHEN ABS(column1 * column2) > ABS(column3 * column4)
THEN column5 * ABS(column1 * column2) * column6
ELSE column5 * ABS(column3 * column4) * column6 END)
Try this:
SELECT SUM(CASE WHEN column1 > column2
THEN column1
ELSE column2 END)
FROM test
Try this... Its not the best performing option, but should work.
SELECT
'LargerValue' = CASE
WHEN SUM(c1) >= SUM(c2) THEN SUM(c1)
ELSE SUM(c2)
END
FROM Test
SELECT
SUM(MaximumValue)
FROM (
SELECT
CASE WHEN column1 > column2
THEN
column1
ELSE
column2
END AS MaximumValue
FROM
Test
) A
FYI, the more complicated case should be fine, so long as all of those columns are part of the same table. It's still looking up the same number of rows, so performance should be very similar to the simpler case (as SQL Server performance is usually IO bound).
How to find max from single row data
-- eg (empid , data1,data2,data3 )
select emplid , max(tmp.a)
from
(select emplid,date1 from table
union
select emplid,date2 from table
union
select emplid,date3 from table
) tmp , table
where tmp.emplid = table.emplid
select sum(id) from (
select (select max(c)
from (select column1 as c
union all
select column2) as cs) id
from test
)
The best answer to this is simply put :
;With Greatest_CTE As
(
Select ( Select Max(ValueField) From ( Values (column1), (column2) ) ValueTable(ValueField) ) Greatest
From Test
)
Select Sum(Greatest)
From Greatest_CTE
It scales a lot better than the other answers with more than two value columns.