a Query results in something like the example below:
col1 col2
A 0
B 0
B 1
C 0
D 1
Now I want no duplicates in col1. but when col1 has duplicates it should give the row where col2 = 1 (or highest value) and don't give the row where col2 = 0. So the result will be:
col1 col2
A 0
B 1
C 0
D 1
How should this query look like?
EDIT:
max works, but there is a thirth colomn, with some text value when col2 = 1
How do I get there result on the right? So when there is duplicate in col1, then get the row where col2 = 1
col1 col2 col3 col1 col2 col3
A 0 A 0
B 0 B 1 XYZ
B 1 XYZ --> C 0
C 0 D 1 YXA
D 1 YXA
Thanks!
Check out the MAX() function: https://learn.microsoft.com/en-us/sql/t-sql/functions/max-transact-sql?view=sql-server-2017
SELECT col1,MAX(col2)
FROM [yourTable]
GROUP BY col1
Related
How can I update rows in a table based on values in a column in the same table?
TableA:
col1 col2 col3 total col_num
NULL NULL NULL 100 1
NULL NULL NULL 200 2
NULL NULL NULL 300 3
Result after update:
TableA:
col1 col2 col3 total col_num
100 NULL NULL 100 1
NULL 200 NULL 200 2
NULL NULL 300 300 3
Unless you resort to somehow dynamically constructing the SQL statement, you can't do this generically. However, for a closed set of columns, you could use a bunch of case expressions:
UPDATE tableA
SET col1 = CASE col_num WHEN 1 THEN total ELSE col1 END,
col2 = CASE col_num WHEN 2 THEN total ELSE col2 END,
col3 = CASE col_num WHEN 3 THEN total ELSE col3 END
You can use case expressions:
update tablea
set
col1 = case when col_num = 1 then total end,
col2 = case when col_num = 2 then total end,
col3 = case when col_num = 3 then total end
You would possibly include some logic to update only non-null columns
update tablea
set
col1 = case when col1 is null and col_num = 1 then total end,
col2 = case when col2 is null and col_num = 2 then total end,
col3 = case when col3 is null and col_num = 3 then total end
where
(col1 is null and col_num = 1)
or (col2 is null and col_num = 2)
or (col3 is null and col_num = 3)
I have table like this
id col1 col2
1 A 1
2 B 0
3 A 1
4 C 1
5 B 0
6 A 0
7 C 1
8 C 1
9 B 1
10 B 0
I need a query something like this
Values 1 0
A 2 1
B 1 3
C 3 0
In the above result the header shows the col2 distinct values (1,0) and rows names represents distinct values of col1. The values in the table shows the counts.
Any suggestion to get the result like this in postgresql?
You need conditional aggregation :
select col1,
sum(case when col2 = 1 then 1 else 0 end) as 1,
sum(case when col2 = 0 then 1 else 0 end) as 0
from table t
group by col1;
You could also use FILTER:
SELECT
col1,
COUNT(*) FILTER (WHERE col2 = 1) AS 1,
COUNT(*) FILTER (WHERE col2 = 0) AS 0,
FROM
foo
GROUP BY
col1;
Here are simpler ways to write this logic. The first is Postgres-specific:
select col1,
sum( (col2 = 1)::int ) as num_1,
sum( (col2 = 0)::int as num_0
from t
group by col1;
The second just uses arithmetic:
select col1,
sum( col2 ) as num_1,
sum( 1 - col2 ) as num_0
from t
group by col1;
TableA has the data as follows:
Col1 Col2 Col3
001 A 0
001 B 0
002 C 0
003 D 0
I want to see the count of records group by Col1 and Col2 where Col3 = 1
May be the query as follows:
Select Col1, Col3, Count(1)
From TableA
Group By Col1, Col2
Where Col3 = 1
Since there are no records with Col3 = 1 no records will be displayed, but I still want to display the values with count as 0.
For example the output is as follows:
Col1 Col2 CountOfRecords
001 A 0
001 B 0
002 C 0
003 D 0
Could you please help me to get output as shown above.
One approach would be to use conditional aggregation:
Select Col1, Col2, Count(case when Col3 = 1 then 1 end) as CountOfRecords
From TableA
Group By Col1, Col2
firstly you write wrong sql statement, you can not use Where clause after Group by clause.. you need to use before group by.. if you want to use filter after group by use Having clause..
second if there is no matching column for 'Col3 = 1' then you did not get any result.. for that you need to use case statement or sub queries.
otherwise do not use group by clause rather than use simple sql statement.
I am trying to figure out the best way to determine, for a specific ID within an Oracle 11g table that has 5 columns and say 100 rows against this ID, if all the column values are the same for these five columns.
For example:
Table Name: TABLE_DATA
Columns:
TD_ID ID COL1 COL2 COL3 COL4 COL5
-----------------------------------------------------------------------
1 1 1 0 3 2 0
2 1 1 0 3 2 0
3 1 1 0 3 2 0
4 1 1 0 3 2 0
5 1 1 0 3 2 0
6 1 1 0 3 2 0
So based on the above example which is just showing 6 rows for now against the ID:1, I want to check that for all COL1, COL2, COL3, COL4 and COL5 values where ID = 1, tell me if all the values are the same from the very first row right down to the last – if so, then return ‘Y’ else return ‘N’.
Given the above example, the result would be ‘Y’ but for instance, if TD_ID = 5 and COL3 = 4 then the result would be ‘N’, as all the column values are not the same, i.e.:
TD_ID ID COL1 COL2 COL3 COL4 COL5
-----------------------------------------------------------------------
1 1 1 0 3 2 0
2 1 1 0 3 2 0
3 1 1 0 3 2 0
4 1 1 0 3 2 0
5 1 1 0 4 2 0
6 1 1 0 3 2 0
I’m just not sure what the fastest approach to determine this is, as the table I am looking at may have more than 2000 rows within the table for a specific ID.
You may also try this :
Select ID
, case when count(distinct COL1 || COL2 || COL3 || COL4 || COL5) > 1
then 'N'
else 'Y' end RESULT
From TABLE_DATA
Group by id;
In this way you group by id and counts how many distinct combination are there.
If only 1 , so all the rows have the same set of values, otherwise it don't.
See if the following is fast enough for you:
SELECT ID, CASE WHEN COUNT(*) > 1 THEN 'No' ELSE 'Yes' END As "Result"
FROM (SELECT DISTINCT ID, COL1, COL2, COL3, COL4, COL5
FROM Table_Data) dist
GROUP BY ID
Here's a little query, you might wanna try out (eventually, you just could try figuring out a better MINUS statement for you):
SELECT
CASE
WHEN ( -- select count of records from a subquery
SELECT
COUNT(1)
FROM
( -- select all rows where id = 1
SELECT
td.col1
,td.col2
,td.col3
,td.col4
,td.col5
FROM
table_data td
WHERE
td.id = 1
MINUS -- substract the first row of the table with id = 1
SELECT
td.col1
,td.col2
,td.col3
,td.col4
,td.col5
FROM
table_data td
WHERE
td.id = 1
AND ROWNUM = 1
)
) = 0 -- check if subquery's count equals 0
AND EXISTS ( -- and exists at least 1 row in the table with id = 1
SELECT
1
FROM
table_data td
WHERE
td.id = 1
AND ROWNUM = 1
) THEN 'Y'
ELSE 'N'
END AS equal
FROM
dual
The table has duplicate IDs from a large table. I want to get one output for each ID. What's the best way to do it?
MyTable
ID Col1 Col2
1 X A
1 Y B
1 Z C
2 X D
2 Y E
3 Z F
3 W G
If Col1 = 'X' and Col2 ='A', then 'Y' is the output for ID1
If Col1 = 'X' and Col2 !='A', then 'N' is the output for ID2
If Col1 != 'X', then 'Y' is the output for ID3
If Col1 = 'X' and Col2 ='A', then 'Y' is the output for ID1
If Col1 = 'X' and Col2 !='A', then 'N' is the output for ID2
If Col1 != 'X', then 'Y' is the output for ID3
I assume the conditions above need to be true for only 1 row per id. You can use conditional aggregation to check whether the condition applies to at least 1 row per group:
select id,
case when count(case when Col1 = 'X' and Col2 = 'A' then 1 end) > 0 then 'Y'
when count(case when Col1 = 'X' and Col2 <> 'A' then 1 end) > 0 then 'N'
when count(case when Col1 = 'X' then 1 end) > 0 then 'Y'
else '?'
end as output
from mytable
group by id