Join then Distinct Count - sql

. I need to find only Employees that are type A. I know this can be done with a JOIN. Then I need to get a count of all distinct EMP_ID for each Region.Also note this will be done in Oracle

These are basic things, you need join and condition on the table containing type = 'A':
select count(distinct emp_id)
from table1 t1
join table2 t2 on t1.job_code = t2.job_code
where t2.type = 'A'
group by t1.region

Could use a CTE.
With someCte
as
(
Select * from table1 t1
Inner join table2 t2 on t1.Job_code = t2.Job_code
where t1.type like 'A' and t2.type like 'A'
)
select distinct emp_id from someCte

Related

How to Group By all fields nested tables in a Left Join query in BigQuery?

I have about 10 tables that I make one big nested tables by rounds with the following query:
R1 AS(
SELECT ANY_VALUE(Table1).*, ARRAY_AGG(( SELECT AS STRUCT Table2.* EXCEPT(ID))) AS Table2
FROM Table1 LEFT JOIN Table2 USING(ID)
GROUP BY Table1.ID),
R2 AS(
SELECT ANY_VALUE(R1).*, ARRAY_AGG(( SELECT AS STRUCT Table3.* EXCEPT(ID))) AS Table3
FROM R1 LEFT JOIN Table3 USING(ID)
GROUP BY R1.ID),
...
SELECT ANY_VALUE(R9).*, ARRAY_AGG(( SELECT AS STRUCT Table10.* EXCEPT(ID))) AS Table10
FROM R9 LEFT JOIN Table10 USING(ID)
The thing is that for example in my first table I can have two records with the same ID but some other fields will be different and I want to consider them as two distinct records and thus group by all the fields of the table while I join.
Then I want to do the same with all the "sub-table" (the R tables in the query), so I will able to group by all the fields of the nested tables.
How can I do it easily ?
I tried GROUP BY Table1.* but it doesn't work...
Thank you in advance
Try to_json_string:
...
FROM Table1 t1
...
GROUP BY to_json_string(t1)
You seem to want something like this:
select *
from table1 t1 left join
(select t2.*
from table2 t2
where true
qualify row_number() over (partition by t2.id order by t2.id) = 0
) t2
using (id)
This uses qualify instead of group by to fetch one row.
If you don't want all rows from from table1, you can whittle them down as well:
select *
from (select t1.*
from table1 t1
where true
qualify row_number() over (partition by id, col1, col2 order by id) = 1
) t1 left join
(select t2.*
from table2 t2
where true
qualify row_number() over (partition by t2.id order by t2.id) = 0
) t2
using (id)
How to Group By all fields ...?
I tried GROUP BY Table1.* but it doesn't work...
Consider below example
SELECT ANY_VALUE(t1).*,
ARRAY_AGG(( SELECT AS STRUCT t2.* EXCEPT(ID))) AS Table2
FROM Table1 t1 LEFT JOIN Table2 t2 USING(ID)
GROUP BY FORMAT('%t', t1)

How to join one table with two different tables with similar fields in BigQuery?

I have 3 tables in BigQuery.
I need to join first one (contains ids), to others (contains list of values for ids). I want to have sum of values by ids from two tables:
SELECT t0.id, sum(values) FROM t0
LEFT JOIN t1 ON t0.id = t1.id
LEFT JOIN t2 ON t0.id = t2.id
GROUP BY id
It does not work with an error Column name values is ambiguous
What is the best way to make it?
SELECT t0.id, sum(t1.values) + sum(t2.values) as sumOfValues FROM t0
LEFT JOIN t1 ON t0.id = t1.id
LEFT JOIN t2 ON t0.id = t2.id
GROUP BY id
I think below better reflect your original idea
#standardSQL
SELECT id, sum(u.values)
FROM t0
LEFT JOIN (
SELECT id, values FROM t1 UNION ALL
SELECT id, values FROM t2
) u
USING (id)
GROUP BY id

SQL Query, how to get data from two tables

Table 1:
ID (unqiue), Name, Address
Table 2:
RecordId, ID (key of table 1), Child name
In one query, I want to retrieve all rows of Table 1 with one additional column which will be the count of all record in table 2 from ID (that is number of children for each ID in table 1). Can't figure out how to format a query to retrieve this data.
Simply Join and apply count
select T1.*, COUNT(T2.RECORDID)AS T2COUNT from Table1 T1
INNER JOIN TABLE2 T2 ON T1.ID= T2.ID
--LEFT JOIN TABLE2 T2 ON T1.ID= T2.ID --if you need 0 child records (from commets by #Cha)
GROUP BY T1.ID , T1.Name, T1.Address
The correct way of doing this will be with a OUTER JOIN:
SELECT a.ID, a.Name, a.Address, b.cnt
FROM Table1 a
LEFT OUTER JOIN
(SELECT ID, count(*) cnt from Table2 GROUP BY ID) b
ON a.ID = b.ID
The incorrect way will be with a help of a correlated sub-query:
SELECT a.ID, a.Name, a.Address,
(SELECT count(*) FROM Table2 b WHERE b.ID = a.ID) as cnt
FROM Table1 a
Here is a discussion about correlated subqueries vs OUTER JOINs, if you are interested
Group by table1 fields and count total records in table2:
here T1 alias of table1 and T2 alias of table2.
select T1.ID, T1.Name, T1.Address, count(T2.ID) as total_records
from table1 as T1
left outer join table2 as T2 on T2.ID=T1.ID
group by T1.ID, T1.Name, T1.Address

Select from table not in another table

I have two tables, each with the following fields: IDnumber, SectionNumber, Date. There is overlapping information in the two tables.
How do I select only rows that do NOT overlap (ie. in one table but not the other)?
You can use a NOT IN in your WHERE clause.
SELECT IDnumber, SectionNumber, Date
FROM table1
WHERE IDnumber NOT IN (SELECT IDnumber FROM table2)
OR NOT EXISTS
SELECT IDnumber, SectionNumber, Date
FROM table1 t1
WHERE NOT EXISTS (SELECT IDnumber FROM table2 t2 WHERE t1.IDnumber = t2.IDnumber)
Which DBMS?
If SQL Server, then it's almost what you wrote in the title...
SELECT *
FROM Table1
WHERE IDnumber NOT IN (SELECT IDnumber FROM Table2)
If you want to compare multiple columns, you need an outer join:
select table1.*
from table1 left outer join
table2
on table1.id = table2.id and
table1.SectionNumber = table2.SectionNumber and
table1.date = table2.date
where table2.id is null
In the case where you might have many matches between the tables, then the join can be inefficient. Assuming you only want those three fields, you can use a trick that avoids the join:
select id, SectionNumber, date
from ((select 0 as IsTable2, id, SectionNumber, date
from table1
) union all
(select 1 as IsTable2, id, SectionNumber, date
from table2
)
) t
group by id, SectionNumber, date
having max(isTable2) = 0
SELECT *
FROM Table1 t1 left join Table2 t2
on t1.id=t2.id
where t2.id is null

Subquery with multiple select statements

to check the subquery having multiple select statement inside 'not in' condition
Eg.
select id from tbl where
id not in (select id from table1) and
id not in (select id from table2) and
id not in (select id from table3)
instead of repeating the same id 'not in' condition , i need the subquery which will check in one shot from multiple tables..
pls help..
Your query is better expressed as:
SELECT id
FROM tbl t
LEFT JOIN table1 t1 on t1.id = t.id
LEFT JOIN table2 t2 on t2.id = t.id
LEFT JOIN table3 t3 on t3.id = t.id
WHERE t1.id IS NULL AND t2.id IS NULL AND t3.id IS NULL
You could use a union, so you just have one in:
select id
from tbl
where id not in
(
select id from table1
union all select id from table2
union all select id from table3
)
Note: not in does not work well with nullable columns, but I assume id is not nullable here.
use union all
like this -->
select f.FIRST_NAME from farmer f where f.ID in (select v.ID from Village v where v.ID in (1,2) union all select s.ID from state s where s.ID in (3,4) )