How to identify unicode text in sql?

Question

Table1 has nvarchar column called umsg which contains unicode text and some time english also.

I want to find out English text present in umsg column.

select * 
from table1 
where 
    RDate >='01/01/2014' and RDate < '09/26/2017' 
    and umsg = convert(varchar(max), umsg)

I used above query that work fine in regional language but some time fail. Suppose col contain text like 'ref no été' I think above message is unicode, if I used above query, it/sql is showing me as English not unicode.How to handle this.

Table :
Id  Date                      Umsg
1   2017-09-12 00:00:00.000   The livers detoxification processes.
2   2017-09-11 00:00:00.000   Purposely added 1 
3   2017-09-10 00:00:00.000   फेंगशुई के छोटे-छोटे टिप्स से आप जीवन की विषमताओं से                       स्वयं को बचा सकते
4   2017-09-17 00:00:00.000    तनाव एक लाइलाज बीमारी कतई नहीं है। कुछ लोग तनाव को                                     आसानी से झेल लेते ह
5   2017-09-17 00:00:00.000    ref no été

Above is data present in my table. But I want data/Output like :

    Id      Date                      Umsg
    1   2017-09-12 00:00:00.000   The livers detoxification processes.
    2   2017-09-11 00:00:00.000   Purposely added 1

Answer 1

check below :

;WITH CTE
 AS (
 SELECT ID,
        DATE,
        umsg,
        CASE
            WHEN(CAST(umsg AS VARCHAR(MAX)) COLLATE SQL_Latin1_General_Cp1251_CS_AS) = umsg
            THEN 0
            ELSE 1
        END HasSpecialChars
 FROM <table_name>)
 SELECT ID,
        DATE,
        umsg
 FROM CTE
 WHERE Date >= '01/01/2014'
       AND Date < '09/26/2017'
       AND HasSpecialChars = 0;

Desired Output :

ID  DATE                     umsg
1   2017-09-12 00:00:00.000  The livers detoxification processes.                                                                     
2   2017-09-11 00:00:00.000  Purposely added 1      

Hope, it will help you.

Answer 2

You did not answer what you want in case there are some unicode and some ascii characters in the same string, so I give you 1 idea and 1 solution for the case if you want only to find "pure English" or "mixed" rows.

You need a table of natural numbers to do this .In case you have no such a table you can generate it like this:

select top 1000000  row_number() over(order by getdate()) as n
into dbo.nums
from sys.messages m1 cross join sys.messages m2;

alter table dbo.nums alter column n int not null;

alter table dbo.nums add constraint PK_nums_n primary key(n); 

Now that you have a table of natural numbers we are going to decompose your strings into single characters to check if ascii(character) = unicode(character):

declare @t table(col Nvarchar(200));
insert into @t values
(N'ref no été'), (N'The livers detoxification processes.'), (N'फेंगशुई के छोटे-छोटे टिप्स से आप जीवन की विषमताओं से')

select t.col, n, substring(t.col, n, 1) as nth_character,
       ascii(substring(t.col, n, 1)) as ascii,
       unicode(substring(t.col, n, 1)) as uni
from @t t join dbo.nums n
       on n.n <= len(t.col); -- this is to give you an idea how to see if it's unicode character or ascii

with cte as
(
select t.col, n, substring(t.col, n, 1) as nth_character,
       ascii(substring(t.col, n, 1)) as ascii,
       unicode(substring(t.col, n, 1)) as uni
from @t t join dbo.nums n
       on n.n <= len(t.col)
)
select col, 
       case
            when sum(case when ascii = uni then 1 else 0 end) = count(*) then 'English only'
            else 'Not only English'
       end as eng_or_not
from cte
group by col -- row level solution

The first part of the code shows you your string character by character along with character's ascii ande unicode code: where they are the same it's ascii character.

The second part just check if all the characters are ascii.