In Snowflake, how do I define a custom sorting order.
ID Language Text
0 ENU a
0 JPN b
0 DAN c
1 ENU d
1 JPN e
1 DAN f
2 etc...
here I want to return all rows sorted by Language in this order: Language = ENU comes first, then JPN and lastly DAN.
Is this even possible?
I would like to order by language, in this order: ENU, JPN, DNA, and so on: ENU, JPN, DNA,ENU,JPN, DAN,ENU, JPN, DAN
NOT: ENU,ENU,ENU,JPN,JPN,JPN,DAN,DAN,DAN
I liked array_position solution of Phil Coulson. It's also possible to use DECODE:
create or replace table mydata ( ID number, Language varchar, Text varchar )
as select * from values
(0, 'JPN' , 'b'),
(0, 'DAN' , 'c' ),
(0, 'ENU' , 'a'),
(1 , 'JPN' , 'e'),
(1 , 'ENU' , 'd'),
(1 , 'DAN' , 'f');
select * from
mydata order by ID, DECODE(Language,'ENU',0,'JPN',1,'DAN',2 );
+----+----------+------+
| ID | LANGUAGE | TEXT |
+----+----------+------+
| 0 | ENU | a |
| 0 | JPN | b |
| 0 | DAN | c |
| 1 | ENU | d |
| 1 | JPN | e |
| 1 | DAN | f |
+----+----------+------+
You basically need 2 levels of sort. I am using arrays to arrange the languages in the order I want and then array_position to assign every language an index based on which they will be sorted. You can achieve the same using either a case expression or decode. To make sure the languages don't repeat within the same id, we use row_number. You can comment out the the row_number() line if that's not a requirement
with cte (id, lang) as
(select 0,'JPN' union all
select 0,'ENU' union all
select 0,'DAN' union all
select 0,'ENU' union all
select 0,'JPN' union all
select 0,'DAN' union all
select 1,'JPN' union all
select 1,'ENU' union all
select 1,'DAN' union all
select 1,'ENU' union all
select 1,'JPN' union all
select 1,'DAN')
select *
from cte
order by id,
row_number() over (partition by id, array_position(lang::variant,['ENU','JPN','DAN']) order by lang), --in case you want languages to not repeat within each id
array_position(lang::variant,['ENU','JPN','DAN'])
This is not to say other answers are wrong.
But here's yet another not using ANSI SQL 'CASE':
SELECT * FROM "Example"
ORDER BY
CASE "Language" WHEN 'ENU' THEN 1
WHEN 'JPN' THEN 2
WHEN 'DAN' THEN 3
ELSE 4 END
,"Language";
Notice the "Language" code is used as a disambiguation for 'other' languages not specified.
It's good defensive programming when dealing with CASE to deal with ELSE.
The ultimate most flexible answer is to have a table with a collation order for languages in it.
Collation order columns are common in many applications.
I've seen them for things like multiple parties to a contract who should appear in a specified order to (of course) the positional order of columns in a table of metadata.
Related
I've started from a table like this
ID | City | Sales
1 | London,New York,Paris,Berlin,Madrid| 20,30,,50
2 | Istanbul,Tokyo,Brussels | 4,5,6
There can be an unlimited amount of cities and/or sales.
I need to get each city and their salesamount their own record. So my result should look something like this:
ID | City | Sales
1 | London | 20
1 | New York | 30
1 | Paris |
1 | Berlin | 50
1 | Madrid |
2 | Istanbul | 4
2 | Tokyo | 5
2 | Brussels | 6
What I got so far is
SELECT ID, splitC.Value, splitS.Value
FROM Table
CROSS APLLY STRING_SPLIT(Table.City,',') splitC
CROSS APLLY STRING_SPLIT(Table.Sales,',') splitS
With one cross apply, this works perfectly. But when executing the query with a second one, it starts to multiply the number of records a lot (which makes sense I think, because it's trying to split the sales for each city again).
What would be an option to solve this issue? STRING_SPLIT is not neccesary, it's just how I started on it.
STRING_SPLIT() is not an option, because (as is mentioned in the documantation) the output rows might be in any order and the order is not guaranteed to match the order of the substrings in the input string.
But you may try with a JSON-based approach, using OPENJSON() and string transformation (comma-separated values are transformed into a valid JSON array - London,New York,Paris,Berlin,Madrid into ["London","New York","Paris","Berlin","Madrid"]). The result from the OPENJSON() with default schema is a table with columns key, value and type and the key column is the 0-based index of each item in this array:
Table:
CREATE TABLE Data (
ID int,
City varchar(1000),
Sales varchar(1000)
)
INSERT INTO Data
(ID, City, Sales)
VALUES
(1, 'London,New York,Paris,Berlin,Madrid', '20,30,,50'),
(2, 'Istanbul,Tokyo,Brussels', '4,5,6')
Statement:
SELECT d.ID, a.City, a.Sales
FROM Data d
CROSS APPLY (
SELECT c.[value] AS City, s.[value] AS Sales
FROM OPENJSON(CONCAT('["', REPLACE(d.City, ',', '","'), '"]')) c
LEFT OUTER JOIN OPENJSON(CONCAT('["', REPLACE(d.Sales, ',', '","'), '"]')) s
ON c.[key] = s.[key]
) a
Result:
ID City Sales
1 London 20
1 New York 30
1 Paris
1 Berlin 50
1 Madrid NULL
2 Istanbul 4
2 Tokyo 5
2 Brussels 6
STRING_SPLIT has no context of what oridinal positions are. In fact, the documentation specifically states that it doesn't care about it:
The order of the output may vary as the order is not guaranteed to match the order of the substrings in the input string.
As a result, you need to use something that is aware of such basic things, such as DelimitedSplit8k_LEAD.
Then you can do something like this:
WITH Cities AS(
SELECT ID,
DSc.Item,
DSc.ItemNumber
FROM dbo.YourTable YT
CROSS APPLY dbo.DelimitedSplit8k_LEAD(YT.City,',') DSc)
Sales AS(
SELECT ID,
DSs.Item,
DSs.ItemNumber
FROM dbo.YourTable YT
CROSS APPLY dbo.DelimitedSplit8k_LEAD(YT.Sales,',') DSs)
SELECT ISNULL(C.ID,S.ID) AS ID,
C.Item AS City,
S.Item AS Sale
FROM Cities C
FULL OUTER JOIN Sales S ON C.ItemNumber = S.ItemNumber;
Of course, however, the real solution is fix your design. This type of design is going to only cause you 100's of problems in the future. Fix it now, not later; you'll reap so many rewards sooner the earlier you do it.
I have a table like the following:
id | type | duedate
-------------------------
1 | original | 01/01/2017
1 | revised | 02/01/2017
2 | original | 03/01/2017
3 | original | 10/01/2017
3 | revised | 09/01/2017
Where there may be either one or two rows for each id. If there are two rows with same id, there would be one with type='original' and one with type='revised'. If there is one row for the id, type will always be 'original'.
What I want as a result are all the rows where type='revised', but if there is only one row for a particular id (thus type='original') then I want to include that row too. So desired output for the above would be:
id | type | duedate
1 | revised | 02/01/2017
2 | original | 03/01/2017
3 | revised | 09/01/2017
I do not know how to construct a WHERE clause that conditionally checks whether there are 1 or 2 rows for a given id, nor am I sure how to use GROUP BY because the revised date could be greater than or less than than the original date so use of aggregate functions MAX or MIN don't work. I thought about using CASE somehow, but also do not know how to construct a conditional that chooses between two different rows of data (if there are two rows) and display one of them rather than the other.
Any suggested approaches would be appreciated.
Thanks!
you can use row number for this.
WITH T AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Type DESC) AS RN
FROM YourTable
)
SELECT *
FROM T
WHERE RN = 1
Is something like this sufficient?
SELECT *
FROM mytable m1
WHERE type='revised'
or 1=(SELECT COUNT(*) FROM mytable m2 WHERE m2.id=m1.id)
You could use a subquery to take the MAX([type]). In this case it works for [type] since alphabetically we want revised first, then original and "r" comes after "o" in the alphabet. We can then INNER JOIN back on the same table with the matching conditions.
SELECT T2.*
FROM (
SELECT id, MAX([type]) AS [MAXtype]
FROM myTABLE
GROUP BY id
) AS dT INNER JOIN myTable T2 ON dT.id = T2.id AND dT.[MAXtype] = T2.[type]
ORDER BY T2.[id]
Gives output:
id type duedate
1 revised 2017-02-01
2 original 2017-03-01
3 revised 2017-09-01
Here is the sqlfiddle: http://sqlfiddle.com/#!6/14121f/6/0
I am reading from a PostgreSQL database (that I do not control) that includes an integer column that acts like an enum, but the enum values are not in the database.
This is not my actual data, but consider an example students table:
id | name | class
==================
1 | Adam | 1
2 | Bruce | 1
3 | Chris | 3
4 | Dave | 4
When SELECTing from this table, it is very common to convert the class column to something more humane:
SELECT
id,
name,
CASE class
WHEN 1 THEN 'Freshman'
WHEN 2 THEN 'Sophomore'
WHEN 3 THEN 'Junior'
WHEN 4 THEN 'Senior'
ELSE 'Unknown'
END
FROM students
Is there a better way to write this? I tried constructing a literal array and using the column to index into it, but if that is possible, I have not figured out the syntax yet.
These don't work:
SELECT {"fr", "so", "ju", "se"}[class] FROM students
SELECT '{"fr", "so", "ju", "se"}'[class] FROM students
You can do this using the ARRAY keyword to construct the array:
SELECT (ARRAY['fr', 'so', 'ju', 'se'])[class] FROM students
In PostgreSQL, array subscripts begin with 1, not 0, so if the enum-like column uses 0 as one of its values, you may need to shift it to get what you want. For example, if the values for class were 0, 1, 2, and 3, you can add 1 to class:
SELECT (ARRAY['fr', 'so', 'ju', 'se'])[class + 1] FROM students
Make it a CTE and do the usual join:
with class (class, class_name) as ( values
(1, 'Freshman'),(2,'Sophomore'),(3,'Junior'),(4,'Senior')
), student (id, name, class) as (values
(1, 'Adam',1),(2,'Bruce',1),(3,'Chris',3),(4,'Dave',4)
)
select id, name, class_name
from
student
inner join
class using (class)
;
id | name | class_name
----+-------+------------
1 | Adam | Freshman
2 | Bruce | Freshman
3 | Chris | Junior
4 | Dave | Senior
https://www.postgresql.org/docs/current/static/sql-select.html#SQL-WITH
The WITH clause allows you to specify one or more subqueries that can be referenced by name in the primary query. The subqueries effectively act as temporary tables or views for the duration of the primary query.
Let's say I have a table with 3 columns (a, b, c) with following values:
+---+------+---+
| a | b | c |
+---+------+---+
| 1 | 5 | 1 |
| 1 | NULL | 1 |
| 2 | NULL | 0 |
| 2 | NULL | 0 |
| 3 | NULL | 5 |
| 3 | NULL | 5 |
+---+------+---+
My desired output: 3
I want to select only those distinct values from column a for which every single occurrence of this value has NULL in column b given that value in c is not 0. Therefore from my desired output, "1" won't come in because there is a "5" in column b even though there is a NULL for the 2nd occurrence of "1". And "2" won't come in because the value of c is 0
The query that I'm using currently which is not working:
SELECT a FROM tab WHERE c!=0 GROUP BY a HAVING COUNT(b) = 0
You can do this using HAVING clause:
SQL Fiddle
SELECT a
FROM tbl
GROUP BY a
HAVING
SUM(CASE
WHEN b IS NOT NULL OR c = 0 THEN 1
ELSE 0 END
) = 0
I think this is the having clause that you want:
select a
from table t
group by a
having count(case when c <> 0 then b end) = 0 and
max(c) > 0
This assumes that c is non-negative.
However, it is not entirely clear why "2" doesn't meet your condition. There are no rows where "c" is not zero. Hence, all such rows have NULL values.
DECLARE #Table TABLE (
A INT
,B INT
,C INT
)
INSERT INTO #Table SELECT 1,5,1
INSERT INTO #Table SELECT 1,NULL,1
INSERT INTO #Table SELECT 2,NULL,0
INSERT INTO #Table SELECT 2,NULL,0
INSERT INTO #Table SELECT 3,NULL,5
INSERT INTO #Table SELECT 3,NULL,5
SELECT
a,max(b) [MaxB],max(C) [MaxC]
FROM #Table
GROUP BY A
HAVING max(b) IS NULL AND ISNULL(max(C),1)<>0
Although you've got 3 answers already, I decided to contribute my 2c...
The query from Ghost comes out most efficient when I check in SQL Server Query analyzer, however, I suspect if your data-set changes that Ghost's query may not be exactly as you require based on what you've written.
I think the query below is what you're looking for at the lowest execution cost in SQL, just basing this on your written requirements as opposed to the data example you've provided (Note: This queries performance is similar to Felix and Gordon's answers, however, I haven't included a conditional "case" statement in my having clause.).
SELECT DISTINCT(a) FROM intTable
GROUP BY a
HAVING SUM(ISNULL(b,0))=0 AND SUM(c)<>0
Hope this helps!
Edit for clarification: I am compiling data weekly, based on Zip_Code, but some Zip_Codes are redundant. I know I should be able to compile a small amount of data, and derive the redundant zip_codes if I can establish relationships.
I want to define a zip code's region by the unique set of items and values that appear in that zip code, in order to create a "Region Table"
I am looking to find relationships by zip code with certain data. Ultimately, I have tables which include similar values for many zip codes.
I have data similar to:
ItemCode |Value | Zip_Code
-----------|-------|-------
1 |10 | 1
2 |15 | 1
3 |5 | 1
1 |10 | 2
2 |15 | 2
3 |5 | 2
1 |10 | 3
2 |10 | 3
3 |15 | 3
Or to simplify the idea, I could even concantenate ItemCode + Value into unique values:
ItemCode+
Value | Zip_Code
A | 1
B | 1
C | 1
A | 2
B | 2
C | 2
A | 3
D | 3
E | 3
As you can see, Zip_Code 1 and 2 have the same distinct ItemCode and Value. Zip_Code 3 however, has different values for certain ItemCodes.
I need to create a table that establishes a relationship between Zip_Codes that contain the same data.
The final table will look something like:
Zip_Code | Region
1 | 1
2 | 1
3 | 2
4 | 2
5 | 1
6 | 3
...etc
This will allow me to collect data only once for each unique Region, and derive the zip_code appropriately.
Things I'm doing now:
I am currently using a query similar to a join, and compares against Zip_Code using something along the lines of:
SELECT a.ItemCode
,a.value
,a.zip_code
,b.ItemCode
,b.value
,b.zip_code
FROM mytable as a, mytable as b -- select from table twice, similar to a join
WHERE a.zip_code = 1 -- left table will have all ItemCode and Value from zip 1
AND b.zip_code = 2 -- right table will have all ItemCode and Value from zip 2
AND a.ItemCode = b.ItemCode -- matches rows on ItemCode
AND a.Value != b.Value
ORDER BY ItemCode
This returns nothing if the two zip codes have exactly the same ItemNum, and Value, and returns a slew of differences between the two zip codes if there are differences.
This needs to move from a manual process to an automated process however, as I am now working with more than 100 zip_codes.
I do not have much programming experience in specific languages, so tools in SSIS are somewhat limited to me. I have some experience using the Fuzzy tools, and feel like there might be something in Fuzzy Grouping that might shine a light on apparent regions, but can't figure out how to set it up.
Does anyone have any suggestions? I have access to SQLServ and its related tools, and Visual Studio. I am trying to avoid writing a program to automate this, as my c# skills are relatively nooby, but will figure it out if necessary.
Sorry for being so verbose: This is my first Question, and the page I agreed to in order to ask a question suggested to explain in detail, and talk about what I've tried...
Thanks in advance for any help I might receive.
Give this a shot (I used the simplified example, but this can easily be expanded). I think the real interesting part of this code is the recursive CTE...
;with matches as (
--Find all pairs of zip_codes that have matching values.
select d1.ZipCode zc1, d2.ZipCode zc2
from data d1
join data d2 on d1.Val=d2.Val
group by d1.ZipCode, d2.ZipCode
having count(*) = (select count(distinct Val) from data where zipcode = d1.Zipcode)
), cte as (
--Trace each zip_code to it's "smallest" matching zip_code id.
select zc1 tempRegionID, zc2 ZipCode
from matches
where zc1<=zc2
UNION ALL
select c.tempRegionID, m.zc2
from cte c
join matches m on c.ZipCode=m.zc1
and c.ZipCode!=m.zc2
where m.zc1<=m.zc2
)
--For each zip_code, use it's smallest matching zip_code as it's region.
select zipCode, min(tempRegionID) as regionID
from cte
group by ZipCode
Demonstrating that there's a use for everything, though normally it makes me cringe: concatenate the values for each zip code into a single field. Store ZipCode and ConcatenatedValues in a lookup table (PK on the one, UQ on the other). Now you can assess which zip codes are in the same region by grouping on ConcatenatedValues.
Here's a simple function to concatenate text data:
CREATE TYPE dbo.List AS TABLE
(
Item VARCHAR(1000)
)
GO
CREATE FUNCTION dbo.Implode (#List dbo.List READONLY, #Separator VARCHAR(10) = ',') RETURNS VARCHAR(MAX)
AS BEGIN
DECLARE #Concat VARCHAR(MAX)
SELECT #Concat = CASE WHEN Item IS NULL THEN #Concat ELSE COALESCE(#Concat + #Separator, '') + Item END FROM #List
RETURN #Concat
END
GO
DECLARE #List AS dbo.List
INSERT INTO #List (Item) VALUES ('A'), ('B'), ('C'), ('D')
SELECT dbo.Implode(#List, ',')