ntext与int MSSQL Server不兼容

Question

I was working on sql when I got error: I don't know how to fix it:

ntext is incompatible with int

my query is like this

select * from table1 where id=textfield union select name,age,(here is an ntext value) from table2

I tried using convert(myfield as nvarchar(max)) but still no luck and error changed to this:

The ntext data type cannot be selected as DISTINCT because it is not comparable.

Answer 1

First :

ntext is deprecated and should be replaced with nvarchar(MAX) .

That aside, ntext is not comparable and can't be used with DISTINCT or = .

When you use the key word UNION to join 2 queries it will automatically call a DISTINCT operation to join only unique data from both queries.

However, nvarchar(MAX) can be used within a DISTINCT thus, the best solution is to update your model to use this type instead of ntext .

If this can't be done, instead of doing select * from table1 go with :

select field1, field2, Cast(field3 as NVarchar(Max)) 
from table1 
union 
select field1, field2, Cast(field3 as nvarchar(MAX))
from table2

Last note :

It is recommended to call your fields explicitly when using a union instead of the * wildcard.