Suppose I have table with following values
A B C
------------------------
5 ABC $20
3 BCD $40
5 BCD $40
2 ABC $20
5 ABC $30
How to write query which would return count of maximum, suppose for column A
it should return value 3 that is count for max which is 5.
You can use sub-query like this one:
SELECT COUNT(*) AS COUNTS FROM Table1
WHERE A = (SELECT MAX(A) AS AD FROM Table1)
See this SQLFiddle
One way (not sure it's the fastest):
SELECT A, count(*) FROM my_table GROUP BY 1 ORDER BY 2 LIMIT 1;
Although not as typical this works as well
(Self anti-join on an inequality)
SELECT
COUNT(t1.a) AS COUNTS
FROM Table1 t1
LEFT JOIN Table1 t2
ON t1.A < t2.A
WHERE
t2.a is null
Demo
Related
This is my data:
id
key
nbr of subs
1
ABC
10
1
XXX
3
2
MNO
120
3
ABC
5
3
FGH
110
I need the key for the record (ID) that has the max nbr of subscriptions:
id
key
nbr of subs
1
ABC
10
2
MNO
120
3
FGH
110
I don't mind deleting the extra records, or electing the ones I need and insert them into other table. Any ideas?
SELECT P.Key, MAX(P.[Nbr of Subcriptions])
FROM P
GROUP BY P.Key;
Thank you very much
You need correlated subquery. Try below SQL-
SELECT t1.ID, t1.Key, t1.NBR FROM Table1 as t1
INNER JOIN (SELECT Table1.ID, Max(Table1.NBR) AS MaxOfNBR
FROM Table1 GROUP BY Table1.ID) as t2 ON (t1.NBR = t2.MaxOfNBR) AND (t1.ID = t2.ID);
I am trying to join the following two tables T1 and T2 on T1.id=T2.id, T1.MonA=T2.MonB such that
Whenever MonA=MonB (iow an entry can be found in both tables),
perform an ordinary join. This is the case for instace for ID A,
MonA=MonB=3
If a MonB entry is in table T2 but no equal MonA entry can be found in
Table T1, the join shall take from table T1 the row where MonA is
maximal. In the sample tables, this is the case for both last rows.
MonA from T1 which are not in T2 shall be ignored
The condition T1.id=T2.id is a necessary precondition, so this always needs to be true!
Table T1
ID MonA Data
A 2 BBB
A 3 CCC
B 4 DDD
B 5 EEE
B 11 EEE
Table T2
ID MonB Organ
A 3 Liver
B 5 Heart
B 7 Kidney
Here is, how the result should look like
ID MonA MonB Data Organ
A 3 3 CCC Liver
B 5 5 EEE Heart
B 11 7 EEE Kidney
I need this to be performed in Teradata SQL and honestly have no idea currently how to tackle the problem. Thanks for help!
EDIT: The may be several entries with identical ID, MonA=MonB, but different Data/Organ columns and i want all of them in the resulting table.
Lets do a join of t1 with t2 as follows
--gets all of the matching records by (id,mona) pairs from t1 with (id,monb) from t2
select a.id,a.mona,b.monb,a.data,b.organ
from t1 a
join t2 b
on a.id=b.id
and a.mona=b.monb
union all /*Here you want only from t2 not there in t1 by id*/
select b.id,x.mona,b.monb,x.data,b.organ
from t2 b
left join t1 a
on a.id=b.id
and a.mona=b.monb
left join (select row_number() over(partition by id order by mona desc) as rnk
,id
,mona
,data
from t1
)x
on b.id=x.id
and x.rnk=1 /*pick up only the largest values arranged by mona*/
where a.mona is null /*Gets only the missing records from t2 which are not in t1*/
This should return the expected result:
SELECT t1.id,t1.mona,t2.monb,t1.data,t2.organ
FROM t1
JOIN t2
ON t1.id=t2.id
QUALIFY
Row_Number()
Over (PARTITION BY t2.id, t2.organ
-- prefer same entry in both tables
ORDER BY CASE WHEN t1.mona = t2.monb THEN 1 ELSE 2 END
-- otherwise take max monA
,t1.mona DESC -- ) = 1
Could anyone help with how to take a single column:
ID
1
2
3
4
and show all possible distinct pairings in 2 columns:
ID ID
1 2
1 3
1 4
2 3
2 4
3 4
You can join the column on itself and arbitrarily decide that the left hand side will always be smaller than the right hand side (as the example shows):
SELECT t1.col, t2.col
FROM mytable t1
JOIN mytable t2 ON t1.col < t2.col
do self join
select t.id,t2.id from t t1 join t t2 on t.id<t1.id
A Simple Cartesian product should do
select distinct a.id as id_a, b.id as id_b
from test a, test b
where a.id<b.id;
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
i am using MYSQL..
I have two tables:
TABLE 1 (TABLE NAME T1)
SL NAME
1 a
2 b
3 c
4 c
table 2 (table name T2)
SL NAME
1 a
2 c
3 c
4 c
Q1: how i count the total number of 'c' in both table?
Q2: which name is max occurrences in both table?
sl is primary key...
my query is:>
select count(*) from t1,t2
where t1.name=t2.name where t1.name='c';
but it showing 6
To count c in both tables you should use UNION, not JOIN.
Syntax:
SELECT ...
UNION [ALL | DISTINCT] SELECT ...
[UNION [ALL | DISTINCT] SELECT ...]
Doc:
http://dev.mysql.com/doc/refman/5.0/en/union.html
Edit:
I'll explain the query that you provided.
select count(*) from t1,t2 where t1.name=t2.name where t1.name='c';
First of all, you use WHERE clause twice which is a syntax error. Should be:
select count(*) from t1,t2 where t1.name=t2.name AND t1.name='c';
And this is the same that:
SELECT count(*) from t1
JOIN t2 ON t1.name=t2.name
WHERE t1.name='c';
You choose only rows with c value so these are the rows, that we will take under consideration:
TABLE 1 (TABLE NAME T1)
SL NAME
3 c
4 c
table 2 (table name T2)
SL NAME
2 c
3 c
4 c
Now, simple JOIN joins every row from table 1 to every row from table 2 (where condition is true of course)
So the result before counting is:
t1.SL t1.NAME t2.SL t2.NAME
3 c 2 c
4 c 3 c
3 c 4 c
4 c 2 c
3 c 3 c
4 c 4 c
This is 6 rows.
Answers for both of your questions.
SELECT name, count(*) as cnt
FROM(select t1.name from t1
union all
select name from t2) as tem
group by name
order by cnt DESC
This query will give you ranking of names ordered by occurrences.
To retrieve only c count, just add WHERE clause. To retrieve only the most occurring name set LIMIT clause to 1.
INSERT INTO #test
SELECT NAME FROM m_t1 WHERE NAME ='c'
UNION all
SELECT NAME FROM m_t2 WHERE NAME ='c'
SELECT count(*) FROM #test