Use PATINDEX to extract a substring in SQL Server? - sql

Question

I have some specific values I want to extract out of a string in SQL Server, but I'm not sure exactly how to get it done with PATINDEX.
Take this string:
declare #Command nvarchar(500) = 'IF dbo.SomeFunctionFn() = 1 BEGIN EXEC SomeStoredProcPR #RowsPerRun=500000, #RowsPerBatch=10000, #NbrDaysToKeepRpt=7 END'
I want to extract out the values of 500000 (for #RowsPerRun), 10000 for #RowsPerBatch and the value of 7 for #NbrDaysToKeepRpt. The values will be of variable length, so I can't guarantee the #RowsPerRun value will be 6 characters.
Is that possible?

Answer 1

DECLARE #Command NVARCHAR(500) =
'IF dbo.SomeFunctionFn() = 1 BEGIN EXEC SomeStoredProcPR #RowsPerRun=500000, #RowsPerBatch=10000, #NbrDaysToKeepRpt=7 END'
SELECT
SearchItem = srch.Txt,
ItemIndex = st.Pos,
ItemLen = t.Ln,
Item = SUBSTRING(pfx.Txt,1,t.Ln)
FROM (VALUES('#RowsPerRun='),('#RowsPerBatch='),('#NbrDaysToKeepRpt=')) AS srch(Txt)
CROSS APPLY (VALUES(CHARINDEX(srch.Txt,#Command),LEN(srch.Txt))) AS st(Pos,Ln)
CROSS APPLY (VALUES(SUBSTRING(#Command, st.Pos+st.Ln, 500))) AS pfx(Txt)
CROSS APPLY (VALUES(PATINDEX('%[^0-9]%',pfx.Txt)-1)) AS t(Ln);
Returns:
SearchItem ItemIndex ItemLen Item
------------------ ----------- ----------- --------
#RowsPerRun= 59 6 500000
#RowsPerBatch= 79 5 10000
#NbrDaysToKeepRpt= 100 1 7
Note that I included a few extra columns to help you understand what's happening.
Update: Against a table
This is how you would apply this logic to a series of values:
DECLARE #sometable TABLE (CommandId INT IDENTITY, Command NVARCHAR(500));
INSERT #sometable (Command)
VALUES
('IF dbo.SomeFunctionFn() = 1 BEGIN EXEC SomeStoredProcPR #RowsPerRun=500000, #RowsPerBatch=10000, #NbrDaysToKeepRpt=7 END'),
('IF dbo.SomeFunctionFn() = 5 BEGIN EXEC SomeStoredProcPR #RowsPerRun=123, #RowsPerBatch=500, #NbrDaysToKeepRpt=20 END'),
('IF dbo.SomeFunctionFn() = 5 BEGIN EXEC XXX #RowsPerRun=43, #RowsPerBatch=1000, #NbrDaysToKeepRpt=120 END'),
('IF dbo.SomeFunctionFn() = 5 BEGIN EXEC abc.yyy #RowsPerRun=43, #RowsPerBatch=1000, #NbrDaysToKeepRpt=120 END');
SELECT t.CommandId, f.SearchItem, f.Item
FROM #sometable AS t
CROSS APPLY
(
SELECT
SearchItem = srch.Txt,
ItemIndex = st.Pos,
ItemLen = t.Ln,
Item = SUBSTRING(pfx.Txt,1,t.Ln)
FROM (VALUES('#RowsPerRun='),('#RowsPerBatch='),('#NbrDaysToKeepRpt=')) AS srch(Txt)
CROSS APPLY (VALUES(CHARINDEX(srch.Txt,t.Command),LEN(srch.Txt))) AS st(Pos,Ln)
CROSS APPLY (VALUES(SUBSTRING(t.Command, st.Pos+st.Ln, 500))) AS pfx(Txt)
CROSS APPLY (VALUES(PATINDEX('%[^0-9]%',pfx.Txt)-1)) AS t(Ln)
) AS f;
Returns:
CommandId SearchItem Item
----------- ------------------ --------
1 #RowsPerRun= 500000
1 #RowsPerBatch= 10000
1 #NbrDaysToKeepRpt= 7
2 #RowsPerRun= 123
2 #RowsPerBatch= 500
2 #NbrDaysToKeepRpt= 20
3 #RowsPerRun= 43
3 #RowsPerBatch= 1000
3 #NbrDaysToKeepRpt= 120
4 #RowsPerRun= 43
4 #RowsPerBatch= 1000
4 #NbrDaysToKeepRpt= 120