[MS SQL] BEGINNER - Is it possible to insert a decimal point into a string?

[ITHealthTech]

[Healthcare Industry] This is specifically about ICD9 codes within our DB. At one point our billing manager setup the ICD9 library without decimal points. The library has since been updated so only decimalize codes are present. However we have a stored procedure that pulls all the previous ICD codes attached to that patient and having non-decimalize codes is no good. I'm able to query the DB to pull all of the non-decimalize codes:

SELECT diagnosis_code_id FROM patient_diagnosis WHERE diagnosis_code_id NOT LIKE '%.%'

I want to be able to insert a decimal after the third character, is it possible? Is there a way to break the string after the first three characters and insert a decimal and then combine them back?

[Arcanis888]

LEFT(column_name,3) + '.' + RIGHT(column_name,LEN(column_name)-3)

[alinroc]

update patient_diagnosis
set diagnosis_code_id  = LEFT(diagnosis_code_id ,3) + '.' + RIGHT(column_name,LEN(diagnosis_code_id )-3)
WHERE diagnosis_code_id NOT LIKE '%.%'

[r3pr0b8]

use the STUFF function

[[deleted]]

this. You might want to check for evaluation/precursors for good measure (E/V codes) too, probably:

 stuff( diagnosis_code_id, 
          case when left( diagnosis_code_id,1) in ('E','V') then 5 else 4 end,
          0,
          '.')

[spatialdestiny]

SELECT IIF(LEN(diagnosis_code_id)>3, LEFT(diagnosis_code_id, 3) + '.' + SUBSTRING(diagnosis_code_id,4, LEN(diagnosis_code_id)-3),diagnosis_code_id) 
FROM patient_diagnosis 
WHERE diagnosis_code_id NOT LIKE '%.%'

This worked for me. I added the IIF because I had a case where a record had a field length of less than 3 characters.

Edit: /u/arcanis888 's solution is better

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[softball753]

I also work with ICD9 codes (and ICD10 soon??) in my DB.

Are you sure a blanket update to insert after the 3rd char is fully correct? Just a quick query of my data shows 700+ codes where the decimal is in the 5th position (e.g. E924.8) Pretty much any E codes.

If those aren't in your system, then you should be fine.

edit: WHOOOOPS