Combine column after left join - sql

How do I combine 3 returned value columns into one column based on which column is not null?
My query is:
SELECT val1,val2,val3
FROM db.table1 t1
LEFT JOIN db.table2 t2 ON t2.pk = t1.t2_fk
LEFT JOIN db.table3 t3 ON t3.pk = t1.t3_fk

use coalesce()
SELECT coalesce(val1,val2,val3) as va
FROM db.table1 t1
left join db.table2 t2
on t2.pk = t1.t2_fk
left join db.table3 t3
on t3.pk = t1.t3_fk

Related

BigQuery Deduplicate rows - No unique columns

I have a bigquery table which is a result of multiple left join tables.
The results are duplicated because of the left join (cartesian product)
How do I de-duplicate the rows so I only see one record?
SELECT T1.Col1,T1.Col2,........
T2.Col1,T2.Col2,........
T3.Col1,T3.Col3,........
T5.Col1,T5.Col2,........
T7.Col1.......
FROM `TABLE1` as T1
LEFT JOIN
`TABLE`as T2 ON T1.CUSTOMER_CODE = T2.CUSTOMER_CODE
LEFT JOIN
`TABLE3` as T3 ON (T1.MIAL_CODE) = T3.MIAL_CODE
LEFT JOIN
`TABLE5` as T5
ON T1.WORK_CODE = T5.WORK_CODE
LEFT JOIN
`TABLE7` as T7
ON T1.CA_DATE = T7.date
ORDER BY CA_DATE
Use DISTINCT:
select distinct *
from mytable
or create a new table:
create or replace table my_new_table
as
select distinct *
from mytable
I used GROUP BY and it worked fine to get rid of duplicates
SELECT T1.Col1,T1.Col2,........
T2.Col1,T2.Col2,........
T3.Col1,T3.Col3,........
T5.Col1,T5.Col2,........
T7.Col1.......
FROM `TABLE1` as T1
LEFT JOIN
`TABLE`as T2 ON T1.CUSTOMER_CODE = T2.CUSTOMER_CODE
LEFT JOIN
`TABLE3` as T3 ON (T1.MIAL_CODE) = T3.MIAL_CODE
LEFT JOIN
`TABLE5` as T5
ON T1.WORK_CODE = T5.WORK_CODE
LEFT JOIN
`TABLE7` as T7
ON T1.CA_DATE = T7.date
GROUP BY T1.Col1,T1.Col2,........
T2.Col1,T2.Col2,........
T3.Col1,T3.Col3,........
T5.Col1,T5.Col2,........
T7.Col1.......
ORDER BY CA_DATE

SQL query to fetch data based on column value

Is it possible to get entire data in one attempt for this scenario? I have this query where I need retrieve product name from another table.
SELECT T1.CASE_ID,
T2.PRODUCT_ID,
T2.LEVEL,
(CASE WHEN T2.LEVEL = 3 THEN T3.PARENT_PRODUCT_ID
WHEN T2.LEVEL = 2 THEN T2.PRODUCT_ID
WHEN T2.LEVEL = 1 THEN NULL END) AS NEW_PRODUCT_ID,
T3.PRODUCT_NAME
FROM TABLE1 T1
LEFT OUTER JOIN TABLE2 T2
ON T1.CASE_ID = T2.CASE_ID
LEFT OUTER JOIN TABLE3 T3
ON T2.PRODUCT_ID=T3.PRODUCT_ID
Right now the T3.PRODUCT_NAME return value based on T2.PRODUCT_ID but what I really need is to able to retrieve data based on the value from NEW_PRODUCT_ID?
Here is my expected output:
Hope this makes sense.
You can use a subquery
SELECT T4.CASE_ID, T4.PRODUCT_ID, T4.LEVEL, T4.NEW_PRODUCT_ID, T5.PRODUCT_NAME
FROM (
SELECT T1.CASE_ID,
T2.PRODUCT_ID,
T2.LEVEL,
(CASE WHEN T2.LEVEL = 3 THEN T3.PARENT_PRODUCT_ID
WHEN T2.LEVEL = 2 THEN T2.PRODUCT_ID
WHEN T2.LEVEL = 1 THEN NULL END) AS NEW_PRODUCT_ID,
T3.PRODUCT_NAME
FROM TABLE1 T1
LEFT OUTER JOIN TABLE2 T2
ON T1.CASE_ID = T2.CASE_ID
LEFT OUTER JOIN TABLE3 T3
ON T2.PRODUCT_ID=T3.PRODUCT_ID
) AS T4
LEFT OUTER JOIN TABLE3 T5
ON T4.NEW_PRODUCT_ID=T5.PRODUCT_ID

How to replace an OR statement from a join in sql server

I have the following query that uses an or statement on a join, so basically if one condition on the join isn't met it must check the next condition. The problem is that with the OR statement it takes really long to run but when I remove one of the OR conditions it runs instantly. is there a better way to do this with both conditions without using the OR statement so it would speed up the query
select t5.TransactionNumber
,t4.ID
,t3.[Entry] AS Amount
,t2.Address AS AddressDetail
,t1.PhoneNumber AS ContactNumber
FROM Table1 t1 (NOLOCK)
JOIN Table2 t2 (NOLOCK) ON t2.FicaID = t1.FicaId
inner join Table3 t3 (NOLOCK) ON (t3.ID = t2.ID AND t3.Code = t2.Code) or (t3.TypeID = t2.TypeID) //on this join i have an or statement if one condition isnt met it must check the next condition
LEFT JOIN Table4 t4 (NOLOCK) ON t4.Result = t3.Result
LEFT JOIN Table5 t5 (NOLOCK) ON t5.AccNum = t3.AccNum
where t1.date>'2018-09-01' and t1.date<'2018-09-30'
By the rule of distributivity in logic,
P OR (Q AND R) can be written as
(P OR Q) AND (P OR R).. maybe that helps?
You could try by using left join and COALESCE function
select t5.TransactionNumber
,t4.ID
,COALESCE(t3.[Entry],t33.[Entry]) AS Amount
,t2.Address AS AddressDetail
,t1.PhoneNumber AS ContactNumber
FROM Table1 t1 (NOLOCK)
JOIN Table2 t2 (NOLOCK) ON t2.FicaID = t1.FicaId
left join Table3 t3 (NOLOCK) ON (t3.ID = t2.ID AND t3.Code = t2.Code)
left join Table3 t33 (t33.TypeID = t2.TypeID) //I moved it to left join
LEFT JOIN Table4 t4 (NOLOCK) ON t4.Result = t3.Result
LEFT JOIN Table5 t5 (NOLOCK) ON t5.AccNum = t3.AccNum
where t1.date>'2018-09-01' and t1.date<'2018-09-30'
You can try below query :
select * from
(
select t5.TransactionNumber
,t4.ID
,t3.[Entry] AS Amount
,t2.Address AS AddressDetail
,t1.PhoneNumber AS ContactNumber
FROM Table1 t1 (NOLOCK)
JOIN Table2 t2 (NOLOCK) ON t2.FicaID = t1.FicaId
inner join Table3 t3 (NOLOCK) ON (t3.ID = t2.ID AND t3.Code = t2.Code)
)A
join Table3 t3 (NOLOCK) ON (A.TypeID = t3.TypeID)
LEFT JOIN Table4 t4 (NOLOCK) ON t4.Result = t3.Result
LEFT JOIN Table5 t5 (NOLOCK) ON t5.AccNum = t3.AccNum
where t1.date>'2018-09-01' and t1.date<'2018-09-30'

How to join 3 tables in sql with or condition

I have 3 tables:
table1
inner join with table2; or:
inner join with table3
The query:
select table1.x
from table1 right outer join
table2
on table1.x = table2.x right outer join
table3
on table1.x = table3.x
but I can only see x values that are in both table2 and table3
Use left join, not right join, along with an appropriate filter condition:
select table1.x
from table1 left join
table2
on table1.x = table2.x left join
table3
on table1.x = table3.x
where table2.x is not null or table3.x is not null;
You might consider writing this using exists:
select t1.*
from table1 t1
where exists (select 1 from table2 t2 where t2.x = t1.x) or
exists (select 1 from table3 t3 where t3.x = t1.x);
That seems like a more natural way to implement your logic -- and you won't get duplicates when x is duplicated in table2 or table3.

Joining tbl1 to select statement twice with join to tbl2 that also joins to tbl3

I'm using SQL server manger.
I have 3 tables
I need a query that pulls t1 ands add an Origin Basin and a Destination Basin.
So far I have the following:
select T1.[Country (destination)], T3.AreaName
From T1
left outer join T2 on
T1.[Country (destination)] = T2.CountryName
inner join T3 on
T2.AreaID = T3.AreaID
inner join T3 on
T2.AreaID = T3.AreaID
Which returns:
Country | Area
However, I'm having trouble doing this for the second country column. I believe you use aliases. I've tried:
select (select AreaName
FROM T3
where T3.AreaID = T2.AreaID) as 'Area Imp',
(select AreaID
From T2
where T2.CountryName = T1.[Country (origin)]) as 'x',
(select AreaID
From T2
where T2.CountryName = T1.[Country (destination)]) as 'y'
FROM T1
But I can't get it to work.
This is what you need to do:
select t1.date, t1.country_destination, t1.country_origin, destination_area.AreaName as area_destination, origin_area.AreaName as area_origin
from t1 as t1 join t2 as destination on t1.country_destination = destination.countryname
join t2 as origin on t1.country_origin = origin.countryname
join t3 as destination_area on t2.areaid = destination_area.areaid
join t3 as origin_area on t2.areaid = origin_area.areaid
You will need to join with the same table twice, both for t2 and t3 so that you get the matching records for your needs.
It helps usually to put aliases that match the purpose of the join (in this case, destination and origin) when writing the query.
I think what you're trying to do is something like this:
select T1.*, T3dest.AreaName, T3orig.AreaName
From
T1
inner join
T2 T2dest on
T1.[Country (destination)] = T2dest.CountryName
inner join
T3 T3dest on
T2dest.AreaID = T3dest.AreaID
inner join
T2 T2orig on
T1.[Country (origin)] = T2orig.CountryName
inner join
T3 T3orig on
T2orig.AreaID = T3orig.AreaID
Note that I've switched to inner joins throughout, at the moment. If you do want left join semantics, you either need to use those for all of the joins to the T2 and T3 tables or you need to change the join order (so that the relevant T3 joins to the T2 tables occur before the attempted join with T1). It's not clear from the sample data if that's required, however.
Try this, You would still want to join on area id's
select T1.Date,T1.[Country (destination)], null [Country (origin)], T3.AreaName [AreaName(Destination)], null [AreaName(Origin)]
From T1
left outer join T2 on
T1.[Country (destination)] = T2.CountryName
inner join T3 on
T2.AreaID = T3.AreaID
union all
select T1.Date,null [Country (destination)], t1.[Country (origin)], Null [AreaName(Destination)], t3. [AreaName(Origin)]
From T1
left outer join T2 on
T1.[Country (Origin)] = T2.CountryName
inner join T3 on
T2.AreaID = T3.AreaID