Select distinct multiple field without NULL - sql

I have a table with Value ID and Value
--------------
| id | value |
--------------
| 1 | NULL |
--------------
| 1 | A |
--------------
| 2 | NULL |
--------------
| 2 | NULL |
--------------
| 3 | B |
--------------
| 3 | B |
--------------
| 3 | B |
--------------
I need to select distinct id and corresponding value from the table. When selecting the Id should be unique and if it is having multiple values in the value field it should retrieve only not NULL values
So the result should be like below.
--------------
| id | value |
--------------
| 1 | A |
--------------
| 2 | NULL |
--------------
| 3 | B |
--------------
How to achieve this? using SQL server 2005

You can use a regular GROUP BY.
The GROUP BY will
eliminate the NULL value from 1 because other values are present.
retain the NULL value for 2 because it only has NULL values.
SQL Statement
SELECT id
, MIN(value)
FROM YourTable
GROUP BY
id
Test script
;WITH q (id, value) AS (
SELECT 1, NULL
UNION ALL SELECT 1, 'A'
UNION ALL SELECT 2, NULL
UNION ALL SELECT 2, NULL
UNION ALL SELECT 3, 'B'
UNION ALL SELECT 3, 'B'
UNION ALL SELECT 3, 'B'
)
SELECT id
, MIN(value)
FROM q
GROUP BY
id

It's a bit convoluted, but it should do the trick:
select distinct x.id, x.value
from table x
where x.value is not null
or not exists
(select y.id
from table y
where y.id = x.id
and y.value is not null)

Related

Join number of pairs in a single table using SQL

I have two tables of events in bigquery that look like as follows. The main idea is two count the number of events in each table (are always pairs of event_id and user_id) and join them in a single table that for each pair in any table it tells the number of events.
table 1:
| event_id | user id |
| -------- | ------- |
| 1 | 1 |
| 2 | 1 |
| 2 | 3 |
| 2 | 5 |
| 1 | 1 |
| 4 | 7 |
table 2:
| event_id | user id |
| -------- | ------- |
| 1 | 1 |
| 3 | 1 |
| 2 | 3 |
I would like to get a table which has the number of events of each table:
| event_id | user id | num_events_table1 | num_events_table2 |
| -------- | ------- | ----------------- | ----------------- |
| 1 | 1 | 2 | 1 |
| 2 | 1 | 1 | 0 |
| 2 | 3 | 1 | 1 |
| 2 | 5 | 1 | 0 |
| 4 | 7 | 1 | 0 |
| 3 | 1 | 0 | 1 |
Any idea of how to do this with sql? I have tried this:
SELECT i1, e1, num_viewed, num_displayed FROM
(SELECT id as i1, event as e1, count(*) as num_viewed
FROM table_1
group by id, event) a
full outer JOIN (SELECT id as i2, event as e2, count(*) as num_displayed
FROM table_2
group by id, event) b
on a.i1 = b.i2 and a.e1 = b.e2
This is not getting exactly what I want. I amb getting i1 which are null and e1 that are null.
Consider below
#standardSQL
with `project.dataset.table1` as (
select 1 event_id, 1 user_id union all
select 2, 1 union all
select 2, 3 union all
select 2, 5 union all
select 1, 1 union all
select 4, 7
), `project.dataset.table2` as (
select 1 event_id, 1 user_id union all
select 3, 1 union all
select 2, 3
)
select event_id, user_id,
countif(source = 1) as num_events_table1,
countif(source = 2) as num_events_table2
from (
select 1 source, * from `project.dataset.table1`
union all
select 2, * from `project.dataset.table2`
)
group by event_id, user_id
if applied to sample data in your question - output is
If I understand correctly, the simplest method is to modify your query via a USING clause along with COALESCE():
SELECT id, event, COALESCE(num_viewed, 0), COALESCE(num_displayed, 0)
FROM (SELECT id, event, count(*) as num_viewed
FROM table_1
GROUP BY id, event
) t1 FULL JOIN
(SELECT id , event, COUNT(*) as num_displayed
FROM table_2
GROUP BY id, event
) t2
USING (id, event);
Note: This requires that the two columns used for the JOIN have the same name. If this is not the case, then you might still need column aliases in the subqueries.
One way is aggregate the union
select event_id, user id, sum(cnt1) cnt1, sum(cnt2) cnt2
from (
select event_id, user id, 1 cnt1, 0 cnt2
from table_1
union all
select event_id, user id, 0 cnt1, 1 cnt2
from table_2 ) t
group by event_id, user id

Filtering a table via another table's values

I have 2 tables:
Value
+----+-------+
| id | name |
+----+-------+
| 1 | Peter |
| 2 | Jane |
| 3 | Joe |
+----+-------+
Filter
+----+---------+------+
| id | valueid | type |
+----+---------+------+
| 1 | 1 | A |
| 2 | 1 | B |
| 3 | 1 | C |
| 4 | 1 | D |
| 5 | 2 | A |
| 6 | 2 | C |
| 7 | 2 | E |
| 8 | 3 | A |
| 9 | 3 | D |
+----+---------+------+
I need to retrieve the values from the Value table where the related Filter table does not contain the type 'B' or 'C'
So in this quick example this would be only Joe.
Please note this is a DB2 DB and i have limited permissions to run selects only.
Or also a NOT IN (<*fullselect*) predicate:
Only that my result is 'Joe', not 'Jane' - and the data constellation would point to that ...
WITH
-- your input, sans reserved words
val(id,nam) AS (
SELECT 1,'Peter' FROM sysibm.sysdummy1
UNION ALL SELECT 2,'Jane' FROM sysibm.sysdummy1
UNION ALL SELECT 3,'Joe' FROM sysibm.sysdummy1
)
,
filtr(id,valueid,typ) AS (
SELECT 1,1,'A' FROM sysibm.sysdummy1
UNION ALL SELECT 2,1,'B' FROM sysibm.sysdummy1
UNION ALL SELECT 3,1,'C' FROM sysibm.sysdummy1
UNION ALL SELECT 4,1,'D' FROM sysibm.sysdummy1
UNION ALL SELECT 5,2,'A' FROM sysibm.sysdummy1
UNION ALL SELECT 6,2,'C' FROM sysibm.sysdummy1
UNION ALL SELECT 7,2,'E' FROM sysibm.sysdummy1
UNION ALL SELECT 8,3,'A' FROM sysibm.sysdummy1
UNION ALL SELECT 9,3,'D' FROM sysibm.sysdummy1
)
-- real query starts here
SELECT
*
FROM val
WHERE id NOT IN (
SELECT valueid FROM filtr WHERE typ IN ('B','C')
)
;
-- out id | nam
-- out ----+-------
-- out 3 | Joe
Or also, a failing left join:
SELECT
val.*
FROM val
LEFT JOIN (
SELECT valueid FROM filtr WHERE typ IN ('B','C')
) filtr
ON filtr.valueid = val.id
WHERE valueid IS NULL
You can use EXISTS, as in:
select *
from value v
where not exists (
select null from filter f
where f.valueid = v.id and f.type in ('B', 'C')
);
Result:
ID NAME
--- -----
3 Joe
See running example at db<>fiddle.

copy one table to another table with diffrent columns

I have a TableA columns are (id,name,A,B,C,p_id)
i want convert TableA to TableB, TableB columns are (id,name,alphabets,alphabets_value,p_id)
Record in TableA
id | name | A | B | C | p_id
1 | xyz | a | b | | 1
2 | opq | a`| b`| c`| 1
Expected In TableB
u_id | id | name | alphabets | alphabets_value | p_id
1 | 1 | xyz | A | a | 1
2 | 1 | xyz | B | b | 1
3 | 2 | opq | A | a` | 1
4 | 2 | opq | B | b` | 1
5 | 2 | opq | C | c` | 1
i want TableB output currently using Microsoft SQL
This is an unpivot, probably most easily explained by a UNION ALL:
SELECT id, name, 'A' as alphabets, a as alphabets_value, p_id
UNION ALL
SELECT id, name, 'B' as alphabets, b as alphabets_value, p_id
UNION ALL
SELECT id, name, 'C' as alphabets, c as alphabets_value, p_id
You can then WHERE to remove the nulls from this, and ROW_NUMBER to give yourself a fake U_id:
SELECT ROW_NUMBER() OVER(ORDER BY id, alphabets) as u_id, x.*
FROM
(
SELECT id, name, 'A' as alphabets, a as alphabets_value, p_id
UNION ALL
SELECT id, name, 'B' as alphabets, b as alphabets_value, p_id
UNION ALL
SELECT id, name, 'C' as alphabets, c as alphabets_value, p_id
)
WHERE
x.alphabets_value IS NOT NULL
Once you get to having a result set you want, INSERT INTO, UPDATE FROM or MERGE to get it into table B is quite trivial

how to select rows with same column_a but different column_b?

I want to select rows in sql server, there's my questions below:
Table1
--------------------------
| Name | Type |
--------------------------
| A | 1 |
| A | 2 |
| B | 1 |
| B | 3 |
| A | 3 |
| C | 1 |
| C | 3 |
| D | 1 |
| D | 2 |
| D | 3 |
| . | . |
| . | . |
Select rows like below:
Table2
--------------------------
| Name | Type |
--------------------------
| A | 1 |
| A | 2 |
| A | 3 |
| D | 1 |
| D | 2 |
| D | 3 |
| . | . |
| . | . |
The select rules is...
Show Name and Type which Type must have 1,2 and 3.
Example: A had 1,2,3 types,so i would select it.
Example: B only has 1,2 types,so i wouldn't select it.
You can use window functions for this:
select name, type
from (
select
t.*,
sum(case when type in (1, 2, 3) then 1 else 0 end)
over(partition by name) cnt
from mytable t
) t
where cnt = 3
This assumes that each (name, type) tuple occurs only once in the original table, which is consistant with your sample data.
Demo on DB Fiddle:
name | type
:--- | ---:
A | 1
A | 2
A | 3
D | 1
D | 2
D | 3
You could use INNER JOINs on the three Type columns to achieve this:
SELECT Table1.[Name],
Table1.[Type]
FROM Table1
INNER JOIN (
SELECT [Name]
FROM Table1
WHERE ([Type] = 1)
) A ON A.[Name] = Table1.[Name]
INNER JOIN (
SELECT [Name]
FROM Table1
WHERE ([Type] = 2)
) B ON B.[Name] = A.[Name]
INNER JOIN (
SELECT [Name]
FROM Table1
WHERE ([Type] = 3)
) C ON C.[Name] = A.[Name]
This outputs:
Name Type
A 1
A 2
A 3
D 1
D 2
D 3
The matching sqlfiddle.
This works by returning rows that contain [Type] = 1, and then ONLY matching rows where [Type] = 2 and [Type] = 3. Then this is joined back to your main table and the results are returned.
Get the names with group by name and set the condition in the having clause:
select * from Table1
where name in (
select name
from Table1
group by name
having count(distinct type) = 3
)
If there are for the column Type other values than 1, 2, 3 then:
select * from Table1
where type in (1, 2, 3) and name in (
select name
from Table1
where type in (1, 2, 3)
group by name
having count(distinct type) = 3
)
See the demo.
Results:
> Name | Type
> :--- | ---:
> A | 1
> A | 2
> A | 3
> D | 1
> D | 2
> D | 3
you can use string_agg if it is sql server 2017 and above or Azure SQL as below:
Select * from #yourTable yt join (
select [name], string_agg([Type], ',') as st_types
from #YourTable
group by [name] ) a
on yt.name = a.[name] and a.st_types like '%1,2,3%'
I give you this, this will work if you have:
A 1
A 2
A 3
A 2
It will then only give you B.
SELECT *
FROM Table1
WHERE Name in (
SELECT Name from
(
SELECT Name, Type, count(Name) c from Table1 where Type = 1
GROUP BY Name, Type
HAVING count(Name) = 1
UNION
SELECT Name, Type, count(Name) c from Table1 where Type = 2
GROUP by Name, Type
HAVING count(Name) = 1
UNION
SELECT Name, Type, count(Name) c from Table1 where Type = 3
GROUP by Name, Type
HAVING count(Name) = 1) t
GROUP by name
HAVING count(c) = 3)
Here is the DEMO

SQL select distinct when one column in and another column greater than

Consider the following dataset:
+---------------------+
| ID | NAME | VALUE |
+---------------------+
| 1 | a | 0.2 |
| 1 | b | 8 |
| 1 | c | 3.5 |
| 1 | d | 2.2 |
| 2 | b | 4 |
| 2 | c | 0.5 |
| 2 | d | 6 |
| 3 | a | 2 |
| 3 | b | 4 |
| 3 | c | 3.6 |
| 3 | d | 0.2 |
+---------------------+
I'm tying to develop a sql select statement that returns the top or distinct ID where NAME 'a' and 'b' both exist and both of the corresponding VALUE's are >= '1'. Thus, the desired output would be:
+---------------------+
| ID | NAME | VALUE |
+---------------------+
| 3 | a | 2 |
+----+-------+--------+
Appreciate any assistance anyone can provide.
You can try to use MIN window function and some condition to make it.
SELECT * FROM (
SELECT *,
MIN(CASE WHEN NAME = 'a' THEN [value] end) OVER(PARTITION BY ID) aVal,
MIN(CASE WHEN NAME = 'b' THEN [value] end) OVER(PARTITION BY ID) bVal
FROM T
) t1
WHERE aVal >1 and bVal >1 and aVal = [Value]
sqlfiddle
This seems like a group by and having query:
select id
from t
where name in ('a', 'b')
having count(*) = 2 and
min(value) >= 1;
No subqueries or joins are necessary.
The where clause filters the data to only look at the "a" and "b" records. The count(*) = 2 checks that both exist. If you can have duplicates, then use count(distinct name) = 2.
Then, you want the minimum value to be 1, so that is the final condition.
I am not sure why your desired results have the "a" row, but if you really want it, you can change the select to:
select id, 'a' as name,
max(case when name = 'a' then value end) as value
you can use in and sub-query
select top 1 * from t
where t.id in
(
select id from t
where name in ('a','b')
group by id
having sum(case when value>1 then 1 else 0)>=2
)
order by id