How to index my rows in sql? - sql

Question

I have the following function:
CREATE FUNCTION dbo.SplitStrings_XML
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
SELECT Item = y.i.value('(./text())[1]', 'nvarchar(4000)')
FROM
(
SELECT x = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>')
+ '</i>').query('.')
) AS a CROSS APPLY x.nodes('i') AS y(i)
);
GO
and the following code:
declare #string nvarchar(max) = 'aaa,1.3,1,bbb,1.5,ccc,2.0,1'
;WITH AllItems as
(
SELECT Item, ROW_NUMBER() OVER(ORDER BY (select null)) as rn
FROM dbo.SplitStrings_XML(#string, ',')
)
, Strings as
(
SELECT Item as Name, ROW_NUMBER() OVER(ORDER BY (select null)) as rn
FROM dbo.SplitStrings_XML(#string, ',')
WHERE ISNUMERIC(Item) = 0
), Doubles as
(
SELECT Item as Measure, ROW_NUMBER() OVER(ORDER BY (select null)) as rn
FROM dbo.SplitStrings_XML(#string, ',')
WHERE ISNUMERIC(Item) = 1 AND CHARINDEX('.', Item) > 0
), Integers as
(
SELECT Item as Value, ROW_NUMBER() OVER(ORDER BY (select null)) as rn
FROM dbo.SplitStrings_XML(#string, ',')
WHERE ISNUMERIC(Item) = 1 AND CHARINDEX('.', Item) = 0
)
SELECT Name, Measure, Value
FROM AllItems A
LEFT JOIN Strings S ON A.rn = S.rn
LEFT JOIN Doubles D ON A.rn = D.rn
LEFT JOIN Integers I ON A.rn = I.rn
WHERE COALESCE(Name, Measure, Value) IS NOT NULL
In this code we got a #string = 'aaa,1.3,1,bbb,1.5,ccc,2.0,1' that returns the chars in a row named Name ,returns the double values in a row named Measure and the int values in a row named Value,the problem is that in my string i have always a Name and Measure but sometimes the Value is missing and I would like to place a NULL value in that space.
So in my example I shouldhave something like
Name Measure Value
---------+--------+-------
aaa 1.3 1
bbb 1.5 NULL
ccc 2.0 1
Instead I have :
Name Measure Value
---------+--------+-------
aaa 1.3 1
bbb 1.5 1
ccc 2.0 NULL

Answer 1

First, I would suggest that you modify the function to return the item number. However, that is not necessary because your row_number() does that.
Then, I assume that a "missing value" means ",,".
If so, I would suggest defining the CTEs as:
WITH AllItems as (
SELECT Item, ROW_NUMBER() OVER (ORDER BY (select null)) as rn
FROM dbo.SplitStrings_XML(#string, ',')
),
Strings as (
SELECT Item as Name, ROW_NUMBER() OVER (ORDER BY (select null)) as rn
FROM AllItems ai
WHERE ai.rn % 3 = 1
),
Doubles as (
SELECT Item as Measure, ROW_NUMBER() OVER (ORDER BY (select null)) as rn
FROM AllItems ai
WHERE ai.rn % 3 = 2
),
Integers as (
SELECT Item as Value, ROW_NUMBER() OVER(ORDER BY (select null)) as rn
FROM AllItems ai
WHERE ai.rn % 3 = 0
)
. . .