I'm trying to use a sub query on a select statement for a field value but I can't seem to figure out the correct syntax. I want to pull a list of company names and as a field for that query, I want to select all the employees for that company.
Any ideas on what I'm doing wrong? The error I get is
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS
T-SQL code:
SELECT
company_name,
company_type,
(SELECT
employee_firstname, employee_lastname
FROM
tblemployees
WHERE
tblemployees.company_id = tblCompanies.company_id) as employees
FROM
tblCompanies
Desired output:
Company Name | Company Type | Employees
----------------------------------------------------------
Test Co | Construction | Bob Smith, Jack Smith, etc
You'll need to concatenate the first and last names using FOR XML PATH or a similar solution. More details on the various methods here.
SELECT DISTINCT
c1.company_name,
c1.company_type,
STUFF((SELECT
', ' + c2.employee_firstname + ' ' + c2.employee_lastname
FROM
tblCompanies c2
WHERE
c1.company_id = c2.company_id
ORDER BY
employee_lastname, employee_firstname
FOR XML PATH(''), TYPE).value('.', 'varchar(max)'), 1, 1, '')
FROM tblCompanies c1
SQL Fiddle
Related
I need to group a table by a set of values together with all matching row numbers/id:s for each set. This operation must be done within the boundaries of SQL Server 2016.
Let's suppose I have the following table (Places):
ID
Country
City
1
Sweden
Stockholm
2
Norway
Oslo
3
Iceland
Reykjavik
4
Sweden
Stockholm
The result that I'm after (No curly-brackets because Stack Overflow thinks it's code, preventing me from posting):
ID
Json
1,4
"Country":"Sweden","City":"Stockholm"
2
"Country":"Norway ","City":"Oslo"
3
"Country":"Iceland ","City":"Reykjavik"
In SQL Server 2017 the above result can be achieved with:
SELECT STRING_AGG(ID) ID, (SELECT Country, City FOR JSON PATH) Json
FROM Places GROUP BY Country, City
I managed to get a similar result in SQL Server 2016 with the code below. (But with my actual amount of data and columns, this solution is too slow.)
SELECT DISTINCT Country, City INTO #temp FROM Places
SELECT (SELECT ID From Places WHERE Country = P.Country AND City = P.City FOR JSON PATH) ID,
(SELECT Country, City FOR JSON Path) Json FROM #temp P
Is there any more performance-effective way of achieving the result that I'm after?
EDIT: As people suggested me to try "FOR XML Path" I tried the code below. This gives the following error "Places.ID is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause ":
SELECT stuff((select ',' + cast(ID as varchar(max)) for xml path ('')), 1, 1, '') ID,
(SELECT Country, City FOR JSON PATH) Json
FROM Places GROUP BY Country, City
Here's a solution you can try with for xml path
Basically select and group the json columns needed and using an apply, use the for xml path solution to aggregate the correlated ID values; because the outer query needs to refer to the output of the apply it needs to be aggregated also, I chose to use max
select max(x.Ids), (select country,city for json path) as [Json]
from t
outer apply (
select Stuff((select ',' + Convert(varchar(10),t2.Id)
from t t2
where t2.city=t.city and t2.country=t.country
for xml path(''),type).value('(./text())[1]','varchar(10)'),1,1,'') as Ids
)x
group by country,city
Working Fiddle
Here is another possible solution:
Declare #testTable Table (ID int, Country varchar(30), City varchar(30));
Insert Into #testTable (ID, Country, City)
Values (1, 'Sweden', 'Stockholm')
, (2, 'Normway', 'Oslo')
, (3, 'Iceland', 'Reykjavik')
, (4, 'Sweden', 'Stockholm');
Select Distinct
ID = stuff((Select concat(',', tt2.ID)
From #testTable tt2
Where tt2.City = tt.City
And tt2.Country = tt.Country
For xml path (''), Type).value('.', 'varchar(10)'), 1, 1, '')
, json = (Select Country, City For JSON PATH)
From #testTable tt;
No idea if this will perform any better though. It is essentially the same - just using DISTINCT instead of GROUP BY.
I want something like:
Particulars Info
Abc 1,2,3
instead of :
Particulars Info
Abc 1
Abc 2
Abc 3
you can use groupconcat
Reference given below::
https://www.w3resource.com/mysql/aggregate-functions-and-grouping/aggregate-functions-and-grouping-group_concat.php
this is the solution for sql-server
select Particulars, stuff((
select ',' + cast(Info as varchar(20))
from YourTable b
where a.Particulars = b.Particulars
for xml path('')), 1, 1, '') as Info
from YourTable a group by Particulars
If you are using SQL Server 2017, you can use STRING_AGG to get your expected result.
SELECT Particulars, STRING_AGG (Info, ',') AS Info
FROM TableName
GROUP BY Particulars;
We handle a lot of sensitive data and I would like to mask passenger names using only the first and last letter of each name part and join these by three asterisks (***),
For example: the name 'John Doe' will become 'J***n D***e'
For a name that consists of two parts this is doable by finding the space using the expression:
LEFT(CardHolderNameFromPurchase, 1) +
'***' +
CASE WHEN CHARINDEX(' ', PassengerName) = 0
THEN RIGHT(PassengerName, 1)
ELSE SUBSTRING(PassengerName, CHARINDEX(' ', PassengerName) -1, 1) +
' ' +
SUBSTRING(PassengerName, CHARINDEX(' ', PassengerName) +1, 1) +
'***' +
RIGHT(PassengerName, 1)
END
However, the passenger name can have more than two parts, there is no real limit to it. How should can I find the indices of all spaces within an expression? Or should I maybe tackle this problem in a different way?
Any help or pointer is much appreciated!
This solution does what you want it to, but is really the wrong approach to use when trying to hide personally identifiable data, as per Gordon's explanation in his answer.
SQL:
declare #t table(n nvarchar(20));
insert into #t values('John Doe')
,('JohnDoe')
,('John Doe Two')
,('John Doe Two Three')
,('John O''Neill');
select n
,stuff((select ' ' + left(s.item,1) + '***' + right(s.item,1)
from dbo.fn_StringSplit4k(t.n,' ',null) as s
for xml path('')
),1,1,''
) as mask
from #t as t;
Output:
+--------------------+-------------------------+
| n | mask |
+--------------------+-------------------------+
| John Doe | J***n D***e |
| JohnDoe | J***e |
| John Doe Two | J***n D***e T***o |
| John Doe Two Three | J***n D***e T***o T***e |
| John O'Neill | J***n O***l |
+--------------------+-------------------------+
String splitting function based on Jeff Moden's Tally Table approach:
create function [dbo].[fn_StringSplit4k]
(
#str nvarchar(4000) = ' ' -- String to split.
,#delimiter as nvarchar(1) = ',' -- Delimiting value to split on.
,#num as int = null -- Which value to return, null returns all.
)
returns table
as
return
-- Start tally table with 10 rows.
with n(n) as (select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1)
-- Select the same number of rows as characters in #str as incremental row numbers.
-- Cross joins increase exponentially to a max possible 10,000 rows to cover largest #str length.
,t(t) as (select top (select len(isnull(#str,'')) a) row_number() over (order by (select null)) from n n1,n n2,n n3,n n4)
-- Return the position of every value that follows the specified delimiter.
,s(s) as (select 1 union all select t+1 from t where substring(isnull(#str,''),t,1) = #delimiter)
-- Return the start and length of every value, to use in the SUBSTRING function.
-- ISNULL/NULLIF combo handles the last value where there is no delimiter at the end of the string.
,l(s,l) as (select s,isnull(nullif(charindex(#delimiter,isnull(#str,''),s),0)-s,4000) from s)
select rn
,item
from(select row_number() over(order by s) as rn
,substring(#str,s,l) as item
from l
) a
where rn = #num
or #num is null;
GO
If you consider PassengerName as sensitive information, then you should not be storing it in clear text in generally accessible tables. Period.
There are several different options.
One is to have reference tables for sensitive information. Any table that references this would have an id rather than the name. Viola. No sensitive information is available without access to the reference table, and that would be severely restricted.
A second method is a reversible compression algorithm. This would allow the the value to be gibberish, but with the right knowledge, it could be transformed back into a meaningful value. Typical methods for this are the public key encryption algorithms devised by Rivest, Shamir, and Adelman (RSA encoding).
If you want to do first and last letters of names, I would be really careful about Asian names. Many of them consist of two or three letters, when written in Latin script. That isn't much hiding. SQL Server does not have simple mechanisms to do this. You can write a user-defined function with a loop to manager the process. However, I view this as the least secure and least desirable approach.
This uses Jeff Moden's DelimitedSplit8K, as well as the new functionality in SQL Server 2017 STRING_AGG. As I don't know what version you're using, I've just gone "whole hog" and assumed you're using the latest version.
Jeff's function is invaluable here, as it returns the ordinal position, something which Microsoft have foolishly omitted from their own function, STRING_SPLIT (and didn't add in 2017 either). Ordinal position is key here, so we can't make use of the built in function.
WITH VTE AS(
SELECT *
FROM (VALUES ('John Doe'),('Jane Bloggs'),('Edgar Allan Poe'),('Mr George W. Bush'),('Homer J Simpson')) V(FullName)),
Masking AS (
SELECT *,
ISNULL(STUFF(Item, 2, LEN(item) -2,'***'), Item) AS MaskedPart
FROM VTE V
CROSS APPLY dbo.delimitedSplit8K(V.Fullname, ' '))
SELECT STRING_AGG(MaskedPart,' ') AS MaskedFullName
FROM Masking
GROUP BY Fullname;
Edit: Nevermind, OP has commented they are using 2008, so STRING_AGG is out of the question. #iamdave, however, has posted an answer which is very similar to my own, just do it the "old fashioned XML way".
Depending on your version of SQL Server, you may be able to use the built-in string split to rows on spaces in the name, do your string formatting, and then roll back up to name level using an XML path.
create table dataset (id int identity(1,1), name varchar(50));
insert into dataset (name) values
('John Smith'),
('Edgar Allen Poe'),
('One Two Three Four');
with split as (
select id, cs.Value as Name
from dataset
cross apply STRING_SPLIT (name, ' ') cs
),
formatted as (
select
id,
name,
left(name, 1) + '***' + right(name, 1) as out
from split
)
SELECT
id,
(SELECT ' ' + out
FROM formatted b
WHERE a.id = b.id
FOR XML PATH('')) [out_name]
FROM formatted a
GROUP BY id
Result:
id out_name
1 J***n S***h
2 E***r A***n P***e
3 O***e T***o T***e F***r
You can do that using this function.
create function [dbo].[fnMaskName] (#var_name varchar(100))
RETURNS varchar(100)
WITH EXECUTE AS CALLER
AS
BEGIN
declare #var_part varchar(100)
declare #var_return varchar(100)
declare #n_position smallint
set #var_return = ''
set #n_position = 1
WHILE #n_position<>0
BEGIN
SET #n_position = CHARINDEX(' ', #var_name)
IF #n_position = 0
SET #n_position = LEN(#var_name)
SET #var_part = SUBSTRING(#var_name, 1, #n_position)
SET #var_name = SUBSTRING(#var_name, #n_position+1, LEN(#var_name))
if #var_part<>''
SET #var_return = #var_return + stuff(#var_part, 2, len(#var_part)-2, replicate('*',len(#var_part)-2)) + ' '
END
RETURN(#var_return)
END
I have a table which store 1 row per 1 survey.
Each survey got about 70 questions, each column present 1 question
SurveyID Q1, Q2 Q3 .....
1 Yes Good Bad ......
I want to pivot this so it reads
SurveyID Question Answer
1 Q1 Yes
1 Q2 Good
1 Q3 Bad
... ... .....
I use {cross apply} to acheive this
SELECT t.[SurveyID]
, x.question
, x.Answer
FROM tbl t
CROSS APPLY
(
select 1 as QuestionNumber, 'Q1' as Question , t.Q1 As Answer union all
select 2 as QuestionNumber, 'Q2' as Question , t.Q2 As Answer union all
select 3 as QuestionNumber, 'Q3' as Question , t.Q3 As Answer) x
This works but I dont want to do this 70 times so I have this select statement
select ORDINAL_POSITION
, COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = mytable
This gives me the list of column and position of column in the table.
So I hope I can somehow join 2nd statement with the 1st statement where by column name. However I am comparing content within a column and a column header here. Is it doable? Is there other way of achieving this?
Hope you can guide me please?
Thank you
Instead of Cross Apply you should use UNPIVOT for this query....
SQL Fiddle
MS SQL Server 2008 Schema Setup:
CREATE TABLE Test_Table(SurveyID INT, Q1 VARCHAR(10)
, Q2 VARCHAR(10), Q3 VARCHAR(10), Q4 VARCHAR(10))
INSERT INTO Test_Table VALUES
(1 , 'Yes', 'Good' , 'Bad', 'Bad')
,(2 , 'Bad', 'Bad' , 'Yes' , 'Good')
Query 1:
SELECT SurveyID
,Questions
,Answers
FROM Test_Table t
UNPIVOT ( Answers FOR Questions IN (Q1,Q2,Q3,Q4))up
Results:
| SurveyID | Questions | Answers |
|----------|-----------|---------|
| 1 | Q1 | Yes |
| 1 | Q2 | Good |
| 1 | Q3 | Bad |
| 1 | Q4 | Bad |
| 2 | Q1 | Bad |
| 2 | Q2 | Bad |
| 2 | Q3 | Yes |
| 2 | Q4 | Good |
If you need to perform this kind of operation to lots of similar tables that have differing numbers of columns, an UNPIVOT approach alone can be tiresome because you have to manually change the list of columns (Q1,Q2,Q3,etc) each time.
The CROSS APPLY based query in the question also suffers from similar drawbacks.
The solution to this, as you've guessed, involves using meta-information maintained by the server to tell you the list of columns you need to operate on. However, rather than requiring some kind of join as you suspect, what is needed is Dynamic SQL, that is, a SQL query that creates another SQL query on-the-fly.
This is done essentially by concatenating string (varchar) information in the SELECT part of the query, including values from columns which are available in your FROM (and join) clauses.
With Dynamic SQL (DSQL) approaches, you often use system metatables as your starting point. INFORMATION_SCHEMA exists in some SQL Server versions, but you're better off using the Object Catalog Views for this.
A prototype DSQL solution to generate the code for your CROSS APPLY approach would look something like this:
-- Create a variable to hold the created SQL code
-- First, add the static code at the start:
declare #SQL varchar(max) =
' SELECT t.[SurveyID]
, x.question
, x.Answer
FROM tbl t
CROSS APPLY
(
'
-- This syntax will add to the variable for every row in the query results; it's a little like looping over all the rows.
select #SQL +=
'select ' + cast(C.column_id as varchar)
+ ' as QuestionNumber, ''' + C.name
+ ''' as Question , t.' + C.name
+ ' As Answer union all
'
from sys.columns C
inner join sys.tables T on C.object_id=T.object_id
where T.name = 'MySurveyTable'
-- Remove final "union all", add closing bracket and alias
set #SQL = left(#SQL,len(#SQL)-10) + ') x'
print #SQL
-- To also execute (run) the dynamically-generated SQL
-- and get your desired row-based output all at the same time,
-- use the EXECUTE keyword (EXEC for short)
exec #SQL
A similar approach could be used to dynamically write SQL for the UNPIVOT approach.
I have a table
ID | OSTag
2145 | BMV123456,BMV234567,BMV123789,BMV124654,BMV456234, BMV908567,
5437 | DAD676776,DAD989898,DAD787656,
5452 | DAD123456,
Query
SELECT DISTINCT bag2.PassengerID,
( SELECT bag1.OSTag +',' AS [text()] FROM REZP8OD01.dbo.Baggage bag1
WHERE bag1.PassengerID=bag2.PassengerID
ORDER BY bag1.PassengerID FOR XML PATH(''))[OSTag] FROM dbo.Baggage bag2
Now I want to add check condition into my sql query that if last item of column OSTag then remove character ','.
Output result like this:
ID | OSTag
2145 | BMV123456,BMV234567,BMV123789,BMV124654,BMV456234, BMV908567
5437 | DAD676776,DAD989898,DAD787656
5452 | DAD123456
SELECT DISTINCT
bag2.PassengerID
,STUFF(( SELECT ',' + bag1.OSTag AS [text()]
FROM REZP8OD01.dbo.Baggage bag1
WHERE bag1.PassengerID=bag2.PassengerID
ORDER BY bag1.PassengerID FOR XML PATH('')), 1,1,'') [OSTag]
FROM dbo.Baggage bag2
Or even better would be
SELECT bag2.PassengerID
,STUFF(( SELECT ',' + bag1.OSTag
FROM REZP8OD01.dbo.Baggage bag1
WHERE bag1.PassengerID=bag2.PassengerID
ORDER BY bag1.PassengerID
FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'), 1,1,'') [OSTag]
FROM dbo.Baggage bag2
GROUP BY bag2.PassengerID
SQL Fiddle
You could do this a number of ways. Probably the easiest is using LEFT.
select LEFT(OSTag, len(OSTag) - 1)
I have to mention that storing delimited values in a single column violates 1NF and is a serious pain to deal with.