IDENTITY retrieval error: No mapping exists from DbType UInt32 to a known SqlDbType.

[a3nick]

Trying to retrieve the inserted identity value on a SqlServer table a receive the following error:

System.ArgumentException
No mapping exists from DbType UInt32 to a known SqlDbType.

this happens using both async or non-async methods and with these solutions

// USING SCOPE_IDENTITY()
var id = await Connection.QuerySingleAsync<int>(@"
    INSERT INTO SOME_TABLE(VAL) VALUES (@VAL); 
    SELECT SCOPE_IDENTITY()"
    , new { VAL });

// USING SCOPE_IDENTITY() WITH CAST
var id = await Connection.QuerySingleAsync<int>(@"
    INSERT INTO SOME_TABLE(VAL) VALUES (@VAL); 
    SELECT CAST(SCOPE_IDENTITY() as int)"
    , new { VAL });

// USING OUTPUT CLAUSE
var id = await Connection.QuerySingleAsync<int>(
    @"INSERT INTO SOME_TABLE(VAL) 
    OUTPUT inserted.Id 
    VALUES (@VAL)"
    , new { VAL });

tried also with QueryAsync<int> and QueryAsync (dynamic result excpected) with the same result

WEB REFS

• https://stackoverflow.com/questions/8270205/how-do-i-perform-an-insert-and-return-inserted-identity-with-dapper
• https://stackoverflow.com/questions/50650985/dapper-for-net-core-insert-into-a-table-and-return-id-of-inserted-row/50651620
• https://dapper-tutorial.net/knowledge-base/37453324/the-importance-of--select-cast-scope-identity---as-int---in-dapperorm

[a3nick]

I've found the problem, isn't related with SCOPE_IDENTITY(). The problem was a parameter (e.g. VAL in my example) that was of type uint?, casting it to int? solved the issue