SQL Server query to check if date has the same digit

case statement to validate if date column is all the same number number (ie. 1s, 2s, etc)

DECLARE @opendate varchar 
SET opendate = '11111111' 

SELECT 
    CASE 
        WHEN opendate LIKE '^([0-9a-z])1+$')
            THEN 'invalid' 
    END AS date

Answer

use

declare @opendate varchar(50)
set @opendate = '11111111111' 
select @opendate, case when patindex('%[^'+left(@opendate,1)+']%',@opendate) = 0 then 'valid' else 'invalid' end

demo in db<>fiddle