Question

Code:

string sqlCommand = @"UPDATE table SET active = 0 WHERE id IN (@CommaSeparatedId)";
string sqlParamName = "CommaSeparatedId";
string sqlParamValue = "111, 222";

try
{
    using (NpgsqlConnection connection = new NpgsqlConnection())
    {
        // Get connection string from Web.config
        connection.ConnectionString = _connectionString;
        connection.Open();
        Int32 rowsAffected;

        using (NpgsqlCommand command = new NpgsqlCommand(sqlCommand, connection))
        {
            NpgsqlParameter sqlParam = new NpgsqlParameter(sqlParamName, NpgsqlTypes.NpgsqlDbType.Varchar);
            // Code below no exception occur, and active not updated to 0
            // sqlParam.Value = sqlParamValue;

            // This code works for only one value
            sqlParam.Value = "111";

            command.Parameters.Add(sqlParam);
            rowsAffected = command.ExecuteNonQuery();
        }
    }
}
catch (NpgsqlException pgEx)
{
    throw pgEx;
}

---

The problem is:

If I’m using the 111, 222 as the sqlParam.Value'rowsAffected = 0, but if I'm using only111or222rowsAffected = 1`. That means it success to updated when only 1 value but will failed if trying to update more than 1 value.

---

Expected Query:

UPDATE table
    SET active = 0
WHERE id IN ('111', '222');

---

What I’m missing in code above?

Answer 1

The problem you are facing is due to the fact that the parameter value “111,222” will be seen by the database engine not like two distinct values, but as one.
The database search for a record with ID = “111,222” and find nothing matching the request.
You should try to use a stored procedure and execute a Dynamic SQL according to the syntax required by PostgreSQL