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sqlxmlt-sqlsql-server-2012sqlxml

Extracting nvarchar value from XML in T-SQL: only one character returned


In my T-SQL procedure I'm trying to extract a string value from the XML node using the .value() method, like this:

declare @criteria xml;
set @criteria = N'<criterion id="DocName"><value>abcd</value></criterion>';

declare @val nvarchar;
set @val = @criteria.value('(criterion[@id="DocName"]/value)[1]', 'nvarchar');

select @val;

I expected to get 'abcd' as a result, but I surprisingly got just 'a'.

So, the value method returns only the 1st character of the string. Can anybody tell me, what am I doing wrong? Thanks a lot.

P.S. I'm using MS SQL Server 2012


Solution

  • Don't use nvarchar without size. From documentation:

    When n is not specified in a data definition or variable declaration statement, the default length is 1. When n is not specified with the CAST function, the default length is 30.

    If you don't know exact length, you always can use nvarchar(max):

    declare @criteria xml;
    set @criteria = N'<criterion id="DocName"><value>abcd</value></criterion>';
    
    declare @val nvarchar(max);
    set @val = @criteria.value('(criterion[@id="DocName"]/value)[1]', 'nvarchar(max)');
    
    select @val;
    

    sql fiddle demo