If there are two tables as mentioned below:
Table 1
day acount
1998-03-01 8
1998-03-04 9
1998-03-05 10
1998-03-09 8
Table 2
day bcount
1998-03-02 9
1998-03-03 7
1998-03-05 4
1998-03-06 3
Can a select query return the data in ascending order in the format below?
Result
day acount bcount
1998-03-01 8 0
1998-03-02 0 9
1998-03-03 0 7
1998-03-04 9 0
1998-03-05 10 4
1998-03-06 3 0
1998-03-09 8 0
I would suggest using a FULL OUTER JOIN to join the tables on the day column to get the result:
select coalesce(t1.day, t2.day) "day",
coalesce(t1.acount, 0) acount,
coalesce(t2.bcount, 0) bcount
from table1 t1
full outer join table2 t2
on t1.day = t2.day;
See SQL Fiddle with Demo. The COALESCE function will return the first non-null result, so this can be used to get the day values in the same column and then replace the nulls in the acount and bcount columns.
#bluefeet's query is the way to go. Only adding some syntactical sugar and corrective:
SELECT day
, coalesce(t1.acount, 0) AS acount
, coalesce(t2.bcount, 0) AS bcount
FROM table1 t1
FULL JOIN table2 t2 USING (day)
SQL Fiddle.
If you use the shorter USING clause for the JOIN condition (possible in this case), you also don't need coalesce(t1.day, t2.day), since this is exactly what day without table qualification resolves to after being listed in the USING clause.
While it is ok to skip the key word AS for table aliases, you should never skip it for column aliases - as documented in the manual in a separate paragraph Omitting the AS Key Word:
In FROM items, both the standard and PostgreSQL allow AS to be omitted
before an alias that is an unreserved keyword. But this is impractical
for output column names, because of syntactic ambiguities.
Related
We have a query that works in BigQuery's Legacy SQL. How do we write it in Standard SQL so it works?
SELECT Hour, Average, L.Key AS Key FROM
(SELECT 1 AS Key, *
FROM test.table_L AS L)
LEFT JOIN
(SELECT 1 AS Key, Avg(Total) AS Average
FROM test.table_R) AS R
ON L.Key = R.Key ORDER BY Hour ASC
Currently the error it gives is:
Equality is not defined for arguments of type ARRAY<INT64> at [4:74]
BigQuery has two modes for queries: Legacy SQL and Standard SQL. We have looked at the BigQuery Standard SQL documentation and also see just one SO answer on Standard SQL joins in BigQuery - but so far, it is unclear to us what the key change needed might be.
Table_L looks like this:
Row Hour
1 A
2 B
3 C
Table_R looks like this:
Row Value
1 10
2 20
3 30
Results Desired:
Row Hour Average(OfR) Key
1 A 20 1
2 B 20 1
3 C 20 1
How do we rewrite this BigQuery Legacy SQL query to work in Standard SQL?
Based on your recent update in question and comments - try below
WITH Table_L AS (
SELECT 1 AS Row, 'A' AS Hour UNION ALL
SELECT 2 AS Row, 'B' AS Hour UNION ALL
SELECT 3 AS Row, 'C' AS Hour
),
Table_R AS (
SELECT 1 AS Row, 10 AS Value UNION ALL
SELECT 2 AS Row, 20 AS Value UNION ALL
SELECT 3 AS Row, 30 AS Value
)
SELECT
Row,
Hour,
(SELECT AVG(Value) FROM Table_R) AS AverageOfR,
1 AS Key
FROM Table_L
Above is for testing
the query you should run in "production" is
SELECT
Row,
Hour,
(SELECT AVG(Value) FROM Table_R) AS AverageOfR,
1 AS Key
FROM Table_L
In case, if for some reason you are bound to JOIN, use below CROSS JOIN version
SELECT
Row,
Hour,
AverageOfR,
1 AS Key
FROM Table_L
CROSS JOIN ((SELECT AVG(Value) AS AverageOfR FROM Table_R))
or below LEFT JOIN version with Key field involved (in case if Key really important for your logic - which somehow I feel is true)
SELECT
Row,
Hour,
AverageOfR,
L.Key AS Key
FROM (SELECT 1 AS Key, Row, Hour FROM Table_L) AS L
LEFT JOIN ((SELECT 1 AS Key, AVG(Value) AS AverageOfR FROM Table_R)) AS R
ON L.Key = R.Key
Your error message suggests that key is not a column in table_L. If no, then don't include it in the query.
It looks like you simply want the average of the total from table_R. You can approach this as:
SELECT l.*, r.average
FROM test.table_L as l CROSS JOIN
(SELECT Avg(Total) as average
FROM test.table_R
) R
ORDER BY l.hour ASC;
I tried to solve one problem but without success.
I have two list of number
{1,2,3,4}
{5,6,7,8,9}
And I have table
ID Number
1 1
1 2
1 7
1 2
1 6
2 8
2 7
2 3
2 9
Now I need to count how many times number from second list come after number from first list but I should count only one by one id
in example table above result should be 2
three matched pars but because we have only two different IDs result is 2 instead 3
Pars:
1 2
1 7
1 2
1 6
2 3
2 9
note. I work with MSSQL
Edit. There is one more column Date which determined order
Edit2 - Solution
i write this query
SELECT * FROM table t
left JOIN table tt ON tt.ID = t.ID
AND tt.Date > t.Date
AND t.Number IN (1,2,3,4)
AND tt.Number IN (6,7,8,9)
And after this I had a plan to group by id and use only one match for each id but execution take a lot time
Here is a query that would do it:
select a.id, min(a.number) as a, min(b.number) as b
from mytable a
inner join mytable b
on a.id = b.id
and a.date < b.date
and b.number in (5,6,7,8,9)
where a.number in (1,2,3,4)
group by a.id
Output is:
id a b
1 1 6
2 3 9
So the two pairs are output each on one line, with the value a belonging to the first group of numbers, and the value of column b to the second group.
Here is a fiddle
Comments on attempt (edit 2 to question)
Later you added a query attempt to your question. Some comments about that attempt:
You don't need a left join because you really want to have a match for both values. inner join has in general better performance, so use that.
The condition t.Number IN (1,2,3,4) does not belong in the on clause. In combination with a left join the result will include t records that violate this condition. It should be put in the where clause.
Your concern about performance may be warranted, but can be resolved by adding a useful index on your table, i.e. on (id, number, date) or (id, date, number)
I'm wondering if it was doable (in one query if possible) to make the query return a default value if a row is missing ? For example takes these 2 tables and given my query takes 2 parameter (place_id and user_id)
T1
place_id / tag_id
1 2
1 3
1 4
2 4
3 2
4 5
T2
user_id / tag_id / count
100 2 1
100 3 20
200 4 30
200 2 2
300 5 22
As you see, the pair user/tag (100,4) is missing. What I would like to archive is a query that will return me these 3 results
tag_id / count
2 1
3 20
4 0
I know that i can do this with something like this but it doesn't really match the final result as it only works if i know in advance the tag_id... and obviously only return 1 row..:
SELECT T1.tag_id, T2.count
from T1 t1
left join T2 t2 on t1.tagId=t2.tag_id
where t1.place_id=1
UNION ALL
select tag_id,0
from T1
where not exist (select 1 from T2 where user_id=100 and tag_id=4)
and tag_id=4;
EDIT: My question was not complete and had missing cases
here is an example (curtesy of #a_horse_with_no_name) http://sqlfiddle.com/#!12/67042/4
Thank you!
The outer join will already take care of what you want.
As t1 is the "left table" of the join, all rows from t1 will be returned. Columns from the "right table" (t2 in your example) will then have a null value. So you only need to convert that null to a 0:
select t1.tag_id, coalesce(t2.cnt, 0)
from T1 t1
left join T2 t2 on t1.tag_Id=t2.tag_id
and t1.place_id = 1;
SQLFiddle example: http://sqlfiddle.com/#!12/ed7bf/1
Unrelated but:
Using count as a column name is a really bad idea, because it will require you to always enclose the column name in double quotes: t2."count" because it is a reserved word. Plus it doesn't really document the purpose of the column. You should find a better name for that.
I am not strong with SQL at all, so here it goes:
I have a table with a column containing doubles.
I would like to select all rows that the maximum difference between them is '5'.
How can I do that?
id value
1 4955.54
2 2884.32
3 8485.45
4 4588.54
5 8487.62
RESULT
id value
3 8485.45
5 8487.62
How can I do that in mySQL ?
Many thanks!
This works, although you mean maximum not minimum difference:
SELECT v.id, v.value
FROM Values v
WHERE EXISTS(
SELECT null from Values v2
WHERE v2.id <> v.id and
ABS(v2.value - v.value) BETWEEN 0 AND 5
)
MSDN: EXISTS (Transact-SQL)
MSDN: ABS (Transact-SQL)
MSDN: BETWEEN (Transact-SQL)
select id, value from table t1
inner join table t2 on t1.id <> t2.id
where ABS(t1.value-t2.value)<=5
It's likely to be inefficient if the set of values is large. There is no obvious way to write this query efficiently, but here goes:
select lo.val
, hi.val
from numbers lo
inner join numbers hi
on hi.val - lo.val >= 5
if the val column is indexed, it might help to add another condition like so:
select lo.val
, hi.val
from numbers lo
inner join numbers hi
on hi.val > lo.val
where hi.val - lo.val >= 5
I have result of two queries like:
Result of query 1
ID Value
1 4
2 0
3 6
4 9
Result of query 2
ID Value
1 6
2 4
3 0
4 1
I want to add values column "Value" and show final result:
Result of Both queries
ID Value
1 10
2 4
3 6
4 10
plz guide me...
select id, sum(value) as value
from (
select id, value from query1
uninon all
select id, value from query2
) x
group by id
Try using a JOIN:
SELECT
T1.ID,
T1.Value + T2.Value AS Value
FROM (...query1...) AS T1
JOIN (...query2...) AS T2
ON T1.Id = T2.Id
You may also need to consider what should happen if there is an Id present in one result but not in the other. The current query will omit it from the results. You may want to investigate OUTER JOIN as an alternative.
A not particularly nice but fairly easy to comprehend way would be:
SELECT ID,SUM(Value) FROM
(
(SELECT IDColumn AS ID,ValueColumn AS Value FROM TableA) t1
OUTER JOIN
(SELECT IDColumn AS ID,ValueColumn AS Value FROM TableB) t2
) a GROUP BY a.ID
It has the benefits of
a) I don't know your actual table structure so you should be able to work out how to get the two 'SELECT's working from your original queries
b) If ID doesn't appear in either table, that's fine