SQL JOINS just similar to excel vlook up but with conditions - sql

I am trying to do 2 tables in SQL to form a third table. Example and the expected output is below
Table1
Date CHI HOS
1/1/1 1 a
1/1/1 2 b
2/1/1 1 a
3/1/1 3 c
Table2
Date CHI CRN
1/1/1 2 b
1/1/1 1 a
2/1/1 2 b
3/1/1 3 d
Table1 _new
Date CHI HOS Hosp_new
1/1/1 1 a a
1/1/1 2 b b
2/1/1 1 a a
3/1/1 3 c d
The conditions are,
the unique key is CHI,
where table1.Hos = table2.CRN then table1.HOS
Where table1.HOS <> table2.CRN then table2.CRN
Where vlook up column in table1 CHI is not found in table2 then table1.HOS
Create a new column HOSP_new and populate with the above
Its a 12 million rows file and I don’t want to have duplicate rows

You can try this:
select distinct t1.date, t1.chi, t1.hos,
case when t1.hos != t2.hos then t2.hos
else t1.hos end as Hosp_new
from table1 t1
left join table2 t2 on t1.chi = t2.chi and t2.date = t1.date

Related

SQL - Delete specific set of raw in a table using another table

Tabel 1 :
ID1
ID2
ID3
MainID
Location
1
A
X
1AX
VIC
2
B
Y
2BY
SYD
3
C
W
3CW
TAS
4
D
Z
4DZ
TAS
Tabel 2 :
SALESID
QTY
AMT
DIFF
1AX
1
100
2
2BY
2
0
3
3CW
3
5
4DZ
3
12
2
Ignore other fields, I need to delete all raws in Tabel 1 where AMT in Tabel 2 has zero or no value for the SALESID.
For example, after the query, only raws containing 1AX & 4DZ should be remain in Tabel 1.
this can be done by subquery
get all MainID from table2 where amt is 0 or null
delete all rows that equal to previous fetched MainID
delete from table1 where MainID in (
select SALESID from table2 where AMT <=0 or AMT is null
)
You can use exists:
delete from table1
where exists (select 1
from table2 t2
where table1.mainid = t2.salesid and
(t2.amt = 0 or t2.amt is null)
);
Thinking an INNER JOIN would be much faster on larger data sets. Something like this:
DELETE
T1
FROM
Table1 T1
INNER JOIN
Table2 T2 ON T2.SalesID = T1.MainID
WHERE
IsNull(T2.Amt,0) = 0

Update rows in a table based on grouping

I have a table with records of the same type with ID's and a grouping. I need to update the id's of table 1 into table 2 based on the record id from largest to smallest using the position.
Table 1
ID
Group
Name
1
A
Apple
2
A
Apple
3
B
Apple
4
B
Apple
Table 2
ID
recordid
position
group
1
1
250
A
2
2
350
A
3
null
450
A
4
null
550
A
5
3
250
B
6
4
350
B
7
null
450
B
8
null
550
B
update table2
set recordid=T1.ID
From Table1 T1
join Table2 T2 on T2.Group=T1.Group
This isn't distinct so I don't think it's right, but I can't figure it out.
where ?????
the problem is you have multiple Id per group , so you have to choose one :
update table2
set recordid= ( select top 1 T1.ID
From Table1 T1
join Table2 T2 on T2.Group=T1.Group
)
where recordid is null

Join two tables, using value from the first unless it is null, otherwise use value from the second

I have three tables which look like those:
TABLE 1
id j_id
1 1
2 2
3 3
TABLE 2
id j_id table1_id
1 57 1
2 84 1
3 1 1
4 9 2
5 2 2
and every j has a value in a third table
id value
1 1abc
2 2bcd
3 3abc
57 57abc
84 84abc
9 9abc
I am trying to write a query which will join table 1 and table 2 and use the J value from the third table instead of the j_id, but the problem is that I want to use the j value from the second table if it exists and otherwise use the value from the first table.
in order the make it clearer this is my query result without using the third table:
tbl1.j_id tbl2.j_id
1 1
1 84
1 57
2 2
2 9
3 null
I want the end query result to use the second table's j value unless it is null:
tbl1.j_id tbl2.j_id j_id
1 1 1abc
1 84 84abc
1 57 57abc
2 2 2abc
2 9 9abc
3 null 3abc
(Question and title edits are more than welcome, weren't that sure how to phrase them..)
You can simply JOIN to table3 on the COALESCE of table2.j_id and table1.j_id:
SELECT t1.j_id AS t1_j_id, t2.j_id AS t2_j_id, t3.value
FROM table1 t1
LEFT JOIN table2 t2 ON t2.table1_id = t1.id
JOIN table3 t3 ON t3.id = COALESCE(t2.j_id, t1.j_id)
Output:
t1_j_id t2_j_id value
1 1 1abc
1 57 57abc
1 84 84abc
2 2 2bcd
2 9 9abc
3 null 3abc
Demo on dbfiddle
One solution is to left join table3 twice:
select
t1.j_id,
t2.j_id,
coalesce(t31.value, t32.value) j_value
from
table1 t1
left join table2 t2 on t2.table1_id = t1.id
left join table3 t31 on t31.id = t2.j_id
left join table3 t32 on t32.id = t1.j_id

How to get Oracle to return unique results in a one to many relationship tables with a left join

I have a three tables
Table 1
Id Department
1 A
2 B
3 C
4 D
Table 2
Id DepartId Name
1 1 ABC
2 1 DEF
3 1 ASD
4 2 FGH
5 2 HJK
6 3 ZXC
Table 3
Id Depart Area
1 A pp
2 B
3 C nn
4 D oo
I need the result
Id Depart Name Area
1 A ABC pp
2 B FGH Null
3 C ZXC nn
4 D NULL oo
I need one matching entry from table 2 and table 3 to corresponding entry in the table 1
Do a left join to also get t1 rows without any reference in the t2 table. GROUP BY to get only 1 row per Department.
select t1.id, t1.Department, min(t2.Name)
from t1
left join t2 on t1.id = t2.DepartId
group by t1.id, t1.Department
I think I would do this with a correlated subquery:
select t1.*,
(select t2.name
from t2
where t1.id = t2.DepartId and rownum = 1
) as t2name
from t1;
This saves the overhead of an aggregation. An index on t2(DepartId, name) is optimal for this query.
by the way not the answer to your specific question but if instead of just one you want all the names you can use listagg
SELECT t1.id,
department,
LISTAGG (name, ',') WITHIN GROUP (ORDER BY name) names
FROM t1, t2
WHERE t1.id = t2.departId(+)
GROUP BY t1.id, department
ORDER BY 1
ID Department Names
1 A ABC,ASD,DEF
2 B FGH, HJK
3 C ZXC
4 D

Compare multiple Rows Based on another table

Lets say I have following tables:
Table1
ID Number
1 2
2 34
3 1 <---- Input (ID = 3) ==> (Number = 1)
4 6
5 5
*6* 7 <---- Want to find (Number = 6) because match in Table2
7 22
and Table2
Number Code Att1 Att2 Att3
1 1 1 <-----|
1 2 1 2 <-----|
6 2 f 2 |
6 3 4 3 2 |
2 4 6 |---Match
22 5 2 2 2 |
5 2 h 3 b |
7 1 1 <-----|
7 2 1 2 <-----|
7 h 5 r
So here is my Problem:
I want the IDs from Table1 that have all Code and Attributes from Table2 that a given (variable) input ID has. At the end I want to create a stored procedure/function that gives me all IDs meeting that condition.
As an Example:
Input-ID: 3. Would return ID 6 because Number 7 (mapped from ID 6 in Table1) has the rows Number 1 (mapped from ID 3 in Table1) has. It has more but that doesn't matter, its just important it has all rows the input one has.
(I can't find a solution to comparing a set of rows to another set of rows that is not known before.)
Thanks for any help!
Edit:
To make it more understandible, here what I want in words step-by-step.
Map input ID to Number in Table1
Get All Rows from Table2 having Number from Step 1
Get all Number that have the same (can have more) Rows as from Step 2
Get IDs for that Numbers (and return them)
Try something like this. Haven't tested it, but basically you inner join on all of the attributes that need to match. The HAVING clause is a crude check to make sure that it matched all the rows. Edit: Forgot to add the input ID WHERE clause.
SELECT t1b.ID FROM
Table1 t1a
INNER JOIN Table2 t2a ON t1a.Number = t2a.Number
INNER JOIN Table2 t2b ON t2a.Number <> t2b.Number AND t2a.Code = t2b.CODE AND t2a.Att1 = t2b.Att1 AND t2a.Att2 = t2b.Att2 AND t2a.Att3 = t2b.Att3
INNER JOIN Table1 t1b ON t1b.Number = t2b.Number
WHERE t1a.ID = 3
GROUP BY t1b.ID
HAVING COUNT(*) = (SELECT COUNT(*) FROM Table1 WHERE ID = t1a.ID)
select t11.ID as Id_To_Find,t12.ID as Id_Found
from Table1 t11
join (
select t21.Number as Found,t22.Number as ToFind from Table2 t21
left join Table2 t22 on t21.Code = t22.Code
and t21.Att1 = t22.Att1
and t21.Att2 = t22.Att2
and t21.Att3 = t22.Att3
and t21.Number <> t22.Number
group by t21.Number,t22.Number
having COUNT(*) = (select COUNT(*) from Table2 where Number = t22.Number))
as FindMatches
on t11.Number = FindMatches.ToFind
join Table1 t12 on t12.Number = FindMatches.Found
Kind of hard to understand what you're trying to acheive. As i understood from your example, you want to match the Number for the input ID in Table1 with any column (correct?) in Table2.
With input ID=3, the SELECT will return Number=7. In the IN (...)-condition, you can specify whichever columns in Table2 you want to match to Table1.Number.
DECLARE #Input INT = 3 -- Your input
SELECT DISTINCT t1.Number
FROM Table1 t
INNER JOIN Table2 t2 ON t.Number IN (t2.Number, t2.Code, t2.Att1, t2.Att2, t2.Att3)
INNER JOIN Table1 t1 ON t2.Number = t1.Number AND t.ID <> t1.ID
WHERE t.ID = #Input