Dynamic CASE expression [duplicate] - sql

Question

This question already has answers here:
Check if a varchar is a number (T-SQL)
(12 answers)
Closed 5 years ago.
Is there anyway to have a case expression that produces different results based upon a value being an integer or a character.
Tables
ID CODE
1 ABC
2 123
3 YHU
4 456
5 ikl
I was looking for an expression that separated the int and char.
Result e.g.
ID CODE Category
1 ABC Char
2 123 Int
3 YHU Char
4 456 Int
5 ikl Char
my general logic
CASE WHEN CODE = INT THEN 'Int' Else 'Char' end as Category
But i didnt know if this was possible in SQL?
I am looking mainly for a way to recognise whether its int or char
UPDATE:
What is the best way to separate the numbers from char, * and - into 2 different categories using case expression
ID CODE Category
1 * No_NUM
2 123 NUM
3 YHU No_NUM
4 456 NUM
5 ikl No_NUM
6 - No_NUM

Answer 1

You can use SQL ISNUMERIC function.
SELECT ID, CODE, CASE ISNUMERIC(CODE) WHEN 1 THEN 'NUM' ELSE 'No_NUM' END AS Category FROM my_table;
Another Variation with REGEX
SELECT ID, CODE, CASE WHEN CODE LIKE '%[0-9]%' THEN 'NUM' ELSE 'No_NUM' END AS Category FROM my_table;

Answer 2

You could use TRY_CAST (SQL Server 2012+)
SELECT *,
CASE WHEN TRY_CAST(CODE AS INT) IS NOT NULL THEN 'Int' ELSE 'Char' END
FROM tab;
I've assumed that column is NOT NULL.
Rextester Demo
EDIT:
It is just text inside CASE:
SELECT *,
CASE WHEN TRY_CAST(CODE AS INT) IS NOT NULL THEN 'NUM' ELSE 'No_NUM' END
FROM tab;
Rextester Demo 2

Answer 3

Use PATINDEX:
create table #temp ([ID] int, [CODE] nvarchar(5))
insert into #temp values (1, '*')
insert into #temp values (2, '123')
insert into #temp values (3, 'YHU')
insert into #temp values (4, '456')
insert into #temp values (5, 'ikl')
Select ID
, CASE when PATINDEX('%[0-9]%', [code]) = 1 then 'num'
-- when PATINDEX('%[^0-9]%', [code]) = 1 then 'no_num'
-- when PATINDEX('%[A-Z]%', [code]) = 1 then 'char'
-- when PATINDEX('%[^A-Z]%', [code]) = 1 then 'no_char' /*etc..*/
ELSE 'no_num' END AS 'Category'
from #temp