Data types ntext and varchar are incompatible in the not equal to operator - 95 small pang

test Field is ntext type
SQL sentence ：select * from A where test=’xxx’
After execution, there will be ：
data type ntext and varchar stay equal to Incompatible error messages in operator .

Is it worth ntext Just type ？
That handle SQL Statement should become ：select * from A where test=convert(ntext,’xxx’)
Results appear ： data type ntext and ntext stay equal to Incompatible error messages in operator .

There are many ways to solve this problem 2 Kind of way :
1. Directly change the database field type ....（ No cure ）
2. hold SQL Statement modified to ：
select * from A where convert(nvarchar(255),test)=’xxx’

Because it doesn't matter text still nvarchar, All mappings in entity classes should be string, because C# only one string Is used to represent strings , However, these two data types are completely different in the database , Therefore, it is impossible to compare them , Especially that one ntext, Many operations cannot be done , Even if it's two ntext type , There is no way to compare . It's fine too select * from A where test like’xxx’