Is this valid SQL? If yes, could you please tell me what it does?
Select *
from MyFirstTable
order by (select min(somefield)
from MySecondTable
where MyFirstTable.id = MySecondTable.id)
A subselect in an "order by", how is that possible?? In effect this SQL query does not sort by a field, but by some value in a row of a field (min). It does not seem logical so sort by anything else other than a field name. But min(somefield) <> somefield! But, yes, this query works and someone at work who teaches me told me this, and i'm sceptical.
Can you tell me what this means? Or just post an equivilant query?
Thanks!
This query orders MyFirstTable by the minimum value of somefield stored in MySecondTable under the same id.
Here's a quick example:
MyFirstTable
id
1
2
3
MySecondTable
id somefield
1 2
1 4
2 1
3 6
3 4
In the above case, your query would return
id
2
1
3
An equivalent query that may make more sense:
SELECT MyFirstTable.ID, MyFirstTable.A, MyFirstTable.B
FROM MyFirstTable
INNER JOIN MySecondTable ON MyFirstTable.ID = MySecondTable.ID
GROUP BY MyFirstTable.ID, MyFirstTable.A, MyFirstTable.B
ORDER BY MIN(MySecondTable.SomeField)
Related
I have been looking but not finding my precise case so I try asking here.
There is a query (which I unfortunately may not disclose) that has this structure:
WITH MAINRESULT AS
(
SELECT ... FROM ... WHERE...GROUP BY...
)
SELECT Name, SUM(MAINRESULT.Amount1 * AnotherAmount) AS MySum FROM MAINRESULT
WHERE .....
GROUP BY Name, AnotherAmount
ORDER BY Name
Now, I get something like this:
**Name** **MySum**
A 5
A 5
B 1
C 2
But I want to have this result SUM-med up so that I get:
**Name** **MySum**
A 10
B 1
C 2
How do I do this by modifying the query struture that I have?
Tried adding a "SELECT FROM" around both the WITH-query parn and the Second SELECT below it but it says I have syntax errors then.
UPDATE:
I had been staring for too long at that Query I missed that the AnotherAmount should not be included in the GROUP BY part. Thanks everyone for pointing it out so quickly!
It looks like you need to remove GROUP BY Name, AnotherAmount and left only GROUP BY Name in your query. Otherwise your results being groupped not only by Name but also by some AnotherAmount field - this may cause unexpected result you're getting.
I have list of Ids 31165,31160,31321,31322,31199,31136 which is dynamic.
When I run query
select id,name from master_movievod where id in(31165,31160,31321,31322,31199,31136);
I get following result
31136|Independence Day
31160|Planet of the Apes
31165|Mrs. Doubtfire
31199|Moulin Rouge
31321|Adult Movie 2
31322|Adult Movie 3
This is sorted list in ascending order.
I want the list in the same order which I give as input like
31165|Mrs. Doubtfire
31160|Planet of the Apes
31321|Adult Movie 2
31322|Adult Movie 3
31199|Moulin Rouge
31136|Independece Day
Without an order by clause, there's no guarantee on the order a database returns the results to you. SQLite, unfortunately, doesn't have something like MySQL's field for custom sorting, but you can jimmy-rig something with a case expression:
SELECT id, name
FROM master_movievod
WHERE id IN (31165, 31160, 31321, 31322, 31199, 31136)
ORDER BY CASE ID WHEN 31165 THEN 0
WHEN 31160 THEN 1
WHEN 31321 THEN 2
WHEN 31322 THEN 3
WHEN 31199 THEN 4
WHEN 31136 THEN 5
END ASC
Unfortunately, SQLite does not have an option like MySQL's FIELD for doing a custom ordering. You are left with two options. The first is that you could create a custom table containing the ordering you want and use that to sort. This option isn't very attractive. The second (and easier) option is to use ORDER BY CASE to achieve the order you want:
SELECT id, name FROM master_movievod
WHERE id IN (31165,31160,31321,31322,31199,31136)
ORDER BY
CASE id
WHEN 31165 THEN 0
WHEN 31160 THEN 1
WHEN 31321 THEN 2
WHEN 31322 THEN 3
WHEN 31199 THEN 4
WHEN 31136 THEN 5
END ASC
update dbo.Sheet1$ set F01 = 0 where ID in(
select top 3 ID from dbo.Sheet1$ where ID in(
select ID, ISNULL(F01,0) + ISNULL(F02,0) + ISNULL(F03,0) as RowSum
from dbo.Sheet1$ where F01 = 1 AND F02 = 1 order by RowSum desc))
Running this code I get the error message:
Msg 1033, Level 15, State 1, Line 1 The ORDER BY clause is invalid in
views, inline functions, derived tables, subqueries, and common table
expressions, unless TOP, OFFSET or FOR XML is also specified.
can I write another query that exactly does the same like above query?
Your query has more issues than just ordering without sampling. For example, when you use a subquery inside the IN () predicate, it cannot return more than 1 column, while your returns two.
Check this one, maybe I have guessed it correctly:
update dbo.Sheet1$ set F01 = 0
where ID in (
select top 3 ID
from dbo.Sheet1$
where F01 = 1 AND F02 = 1
order by ISNULL(F01,0) + ISNULL(F02,0) + ISNULL(F03,0) desc
);
2 possible reasons for the errors are:
1) You subquery has condition IN which tries to look for 2 column in the subquery while you can have only 1 column while you query IN
2) Your subquery can not use Order By because whether you're going to sort or not, it'll look for matching records from the subquery result set and update the records. So there won't be any meaning of using Order By in your subquery. Whether you'll keep Order By or remove Order By in your subquery, it'll give you the same output.
Hope this helps!
SELECT * FROM tblItems
WHERE itemId IN (9,1,4)
Returns in the order that SQL finds them in (which happens to be 1, 4, 9) however, I want them returned in the order that I specified in the array.
I know I could reorder them after in my native language (obj c), but is there a neat way to do this in SQL?
Somthing like this would be great:
ORDER BY itemId (9,1,4) -- <-- this dosn't work :)
Probably the best way to do this is create a table of item IDs, which also includes a rank order. Then you can join and sort by the rank order.
Create a table like this:
itemID rank
9 1
1 2
4 3
Then your query would look like this:
select tblItems.* from tblItems
inner join items_to_get on
items_to_get.itemID = tblItems.itemID
order by rank
Use a CASE expression to map the ID values to an increasing sequence:
... ORDER BY CASE itemId
WHEN 9 THEN 1
WHEN 1 THEN 2
ELSE 3
END
I had the same task once in a mysql environment.
I ended up using
ORDER BY FIND_IN_SET(itemID, '9,1,4')
this is working for me since then. I hope it also works for sqlite
You can add a case construct to your select clause.
select case when itemid = 9 then 1
when itemid = 1 then 2 else 3 end sortfield
etc
order by sortfield
You could create a procedure to order the data in SQL, but that would be much more complicated than its native language counterpart.
There's no "neat way" to resort the data like that in SQL -- the WHERE clause of a SELECT simply says "if these criteria are matched, include the row"; it's not (and it cannot be) an ordering criterion.
Hi I know how to use the group by clause for sql. I am not sure how to explain this so Ill draw some charts. Here is my original data:
Name Location
----------------------
user1 1
user1 9
user1 3
user2 1
user2 10
user3 97
Here is the output I need
Name Location
----------------------
user1 1
9
3
user2 1
10
user3 97
Is this even possible?
The normal method for this is to handle it in the presentation layer, not the database layer.
Reasons:
The Name field is a property of that data row
If you leave the Name out, how do you know what Location goes with which name?
You are implicitly relying on the order of the data, which in SQL is a very bad practice (since there is no inherent ordering to the returned data)
Any solution will need to involve a cursor or a loop, which is not what SQL is optimized for - it likes working in SETS not on individual rows
Hope this helps
SELECT A.FINAL_NAME, A.LOCATION
FROM (SELECT DISTINCT DECODE((LAG(YT.NAME, 1) OVER(ORDER BY YT.NAME)),
YT.NAME,
NULL,
YT.NAME) AS FINAL_NAME,
YT.NAME,
YT.LOCATION
FROM YOUR_TABLE_7 YT) A
As Jirka correctly pointed out, I was using the Outer select, distinct and raw Name unnecessarily. My mistake was that as I used DISTINCT , I got the resulted sorted like
1 1
2 user2 1
3 user3 97
4 user1 1
5 3
6 9
7 10
I wanted to avoid output like this.
Hence I added the raw id and outer select
However , removing the DISTINCT solves the problem.
Hence only this much is enough
SELECT DECODE((LAG(YT.NAME, 1) OVER(ORDER BY YT.NAME)),
YT.NAME,
NULL,
YT.NAME) AS FINAL_NAME,
YT.LOCATION
FROM SO_BUFFER_TABLE_7 YT
Thanks Jirka
If you're using straight SQL*Plus to make your report (don't laugh, you can do some pretty cool stuff with it), you can do this with the BREAK command:
SQL> break on name
SQL> WITH q AS (
SELECT 'user1' NAME, 1 LOCATION FROM dual
UNION ALL
SELECT 'user1', 9 FROM dual
UNION ALL
SELECT 'user1', 3 FROM dual
UNION ALL
SELECT 'user2', 1 FROM dual
UNION ALL
SELECT 'user2', 10 FROM dual
UNION ALL
SELECT 'user3', 97 FROM dual
)
SELECT NAME,LOCATION
FROM q
ORDER BY name;
NAME LOCATION
----- ----------
user1 1
9
3
user2 1
10
user3 97
6 rows selected.
SQL>
I cannot but agree with the other commenters that this kind of problem does not look like it should ever be solved using SQL, but let us face it anyway.
SELECT
CASE main.name WHERE preceding_id IS NULL THEN main.name ELSE null END,
main.location
FROM mytable main LEFT JOIN mytable preceding
ON main.name = preceding.name AND MIN(preceding.id) < main.id
GROUP BY main.id, main.name, main.location, preceding.name
ORDER BY main.id
The GROUP BY clause is not responsible for the grouping job, at least not directly. In the first approximation, an outer join to the same table (LEFT JOIN below) can be used to determine on which row a particular value occurs for the first time. This is what we are after. This assumes that there are some unique id values that make it possible to arbitrarily order all the records. (The ORDER BY clause does NOT do this; it orders the output, not the input of the whole computation, but it is still necessary to make sure that the output is presented correctly, because the remaining SQL does not imply any particular order of processing.)
As you can see, there is still a GROUP BY clause in the SQL, but with a perhaps unexpected purpose. Its job is to "undo" a side effect of the LEFT JOIN, which is duplication of all main records that have many "preceding" ( = successfully joined) records.
This is quite normal with GROUP BY. The typical effect of a GROUP BY clause is a reduction of the number of records; and impossibility to query or test columns NOT listed in the GROUP BY clause, except through aggregate functions like COUNT, MIN, MAX, or SUM. This is because these columns really represent "groups of values" due to the GROUP BY, not just specific values.
If you are using SQL*Plus, use the BREAK function. In this case, break on NAME.
If you are using another reporting tool, you may be able to compare the "name" field to the previous record and suppress printing when they are equal.
If you use GROUP BY, output rows are sorted according to the GROUP BY columns as if you had an ORDER BY for the same columns. To avoid the overhead of sorting that GROUP BY produces, add ORDER BY NULL:
SELECT a, COUNT(b) FROM test_table GROUP BY a ORDER BY NULL;
Relying on implicit GROUP BY sorting in MySQL 5.6 is deprecated. To achieve a specific sort order of grouped results, it is preferable to use an explicit ORDER BY clause. GROUP BY sorting is a MySQL extension that may change in a future release; for example, to make it possible for the optimizer to order groupings in whatever manner it deems most efficient and to avoid the sorting overhead.
For full information - http://academy.comingweek.com/sql-groupby-clause/
SQL GROUP BY STATEMENT
SQL GROUP BY clause is used in collaboration with the SELECT statement to arrange identical data into groups.
Syntax:
1. SELECT column_nm, aggregate_function(column_nm) FROM table_nm WHERE column_nm operator value GROUP BY column_nm;
Example :
To understand the GROUP BY clauserefer the sample database.Below table showing fields from “order” table:
1. |EMPORD_ID|employee1ID|customerID|shippers_ID|
Below table showing fields from “shipper” table:
1. | shippers_ID| shippers_Name |
Below table showing fields from “table_emp1” table:
1. | employee1ID| first1_nm | last1_nm |
Example :
To find the number of orders sent by each shipper.
1. SELECT shipper.shippers_Name, COUNT (orders.EMPORD_ID) AS No_of_orders FROM orders LEFT JOIN shipper ON orders.shippers_ID = shipper.shippers_ID GROUP BY shippers_Name;
1. | shippers_Name | No_of_orders |
Example :
To use GROUP BY statement on more than one column.
1. SELECT shipper.shippers_Name, table_emp1.last1_nm, COUNT (orders.EMPORD_ID) AS No_of_orders FROM ((orders INNER JOIN shipper ON orders.shippers_ID=shipper.shippers_ID) INNER JOIN table_emp1 ON orders.employee1ID = table_emp1.employee1ID)
2. GROUP BY shippers_Name,last1_nm;
| shippers_Name | last1_nm |No_of_orders |
for more clarification refer my link
http://academy.comingweek.com/sql-groupby-clause/