in SQL, how can I find duplicate string values within the same record? - sql

Question

Sample table
Record Number | Filter | Filters_Applied
----------------------------------------------
1 | yes | red, blue
2 | yes | green
3 | no |
4 | yes | red, red, blue
Is it possible to query all records where there are duplicate string values? For example, how could I query to pull record 4 where the string "red" appeared twice? Except in the table that I am dealing with, there are far more string values that can populate in the "filters_applied" column.
CLARIFICATION I am working out of Periscope and pulling data using SQL.

Answer 1

I assume that you have to check that in the logical page.
You can query the table with like '%red%'.
select Filters_Applied from table where Filters_Applied like '%red%';
You will get the data which has red at least one. Then, doing some string analysis in logic page.
In php, You can use the substr_count function to determine the number of occurrences of the string.
//the loop to load db query
while(){
$number= substr_count("Filters_Applied",red);
if($number>1){
echo "this".$Filters_Applied.">1"
}
}

Answer 2

for SQL-SERVER or other versions which can run these functions
Apply this logic
declare #val varchar(100) = 'yellow,blue,white,green'
DECLARE #find varchar(100) = 'green'
select #val = replace(#val,' ','') -- remove spaces
select #val;
select (len(#val)-len(replace(#val,#find,'')))/len(#find) [recurrence]

Answer 3

Create this Function which will parse string into rows and write query as given below. This will works for SQL Server.
CREATE FUNCTION [dbo].[StrParse]
(#delimiter CHAR(1),
#csv NTEXT)
RETURNS #tbl TABLE(Keys NVARCHAR(255))
AS
BEGIN
DECLARE #len INT
SET #len = Datalength(#csv)
IF NOT #len > 0
RETURN
DECLARE #l INT
DECLARE #m INT
SET #l = 0
SET #m = 0
DECLARE #s VARCHAR(255)
DECLARE #slen INT
WHILE #l <= #len
BEGIN
SET #l = #m + 1--current position
SET #m = Charindex(#delimiter,Substring(#csv,#l + 1,255))--next delimiter or 0
IF #m <> 0
SET #m = #m + #l
--insert #tbl(keys) values(#m)
SELECT #slen = CASE
WHEN #m = 0 THEN 255 --returns the remainder of the string
ELSE #m - #l
END --returns number of characters up to next delimiter
IF #slen > 0
BEGIN
SET #s = Substring(#csv,#l,#slen)
INSERT INTO #tbl
(Keys)
SELECT #s
END
SELECT #l = CASE
WHEN #m = 0 THEN #len + 1 --breaks the loop
ELSE #m + 1
END --sets current position to 1 after next delimiter
END
RETURN
END
GO
CREATE TABLE Table1# (RecordNumber int, [Filter] varchar(5), Filters_Applied varchar(100))
GO
INSERT INTO Table1# VALUES
(1,'yes','red, blue')
,(2,'yes','green')
,(3,'no ','')
,(4,'yes','red, red, blue')
GO
--This query will return what you are expecting
SELECT t.RecordNumber,[Filter],Filters_Applied,ltrim(rtrim(keys)), count(*)NumberOfRows
FROM Table1# t
CROSS APPLY dbo.StrParse (',', t.Filters_Applied)
GROUP BY t.RecordNumber,[Filter],Filters_Applied,ltrim(rtrim(keys)) HAVING count(*) >1

Answer 4

You didn't state your DBMS, but in Postgres this isn't that complicated:
select st.*
from sample_table st
join lateral (
select count(*) <> count(distinct trim(item)) as has_duplicates
from unnest(string_to_array(filters_applied,',')) as t(item)
) x on true
where x.has_duplicates;
Online example: http://rextester.com/TJUGJ44586
With the exception of string_to_array() the above is actually standard SQL