string sql1 = "SELECT COUNT(*) FROM TEST WHERE F5 IS NULL AND F6 IS NULL";
string sql2 = "SELECT COUNT(*) FROM TEST WHERE F5=@F5 AND F6=@F6";SqlConnection conn = new SqlConnection("×××");
SqlCommand comm = conn.CreateCommand();
comm.CommandType = CommandType.Text;
SqlParameter param1 = new SqlParameter("@F5", DBNull.Value);
SqlParameter param2 = new SqlParameter("@F6", DBNull.Value);comm.Parameters.Add(param1);
comm.Parameters.Add(param2);
comm.CommandText = sql2;
try
{
conn.Open();
Console.WriteLine(comm.ExecuteScalar()); //打印结果
comm.CommandText = sql1;
Console.WriteLine(comm.ExecuteScalar()); //打印另一个结果
}
catch
{
throw;
}
finally
{
conn.Close();
}一个结果是0(sqlparameter方式),另一个是12。谁能解释一下么?
string sql2 = "SELECT COUNT(*) FROM TEST WHERE F5=@F5 AND F6=@F6";SqlConnection conn = new SqlConnection("×××");
SqlCommand comm = conn.CreateCommand();
comm.CommandType = CommandType.Text;
SqlParameter param1 = new SqlParameter("@F5", DBNull.Value);
SqlParameter param2 = new SqlParameter("@F6", DBNull.Value);comm.Parameters.Add(param1);
comm.Parameters.Add(param2);
comm.CommandText = sql2;
try
{
conn.Open();
Console.WriteLine(comm.ExecuteScalar()); //打印结果
comm.CommandText = sql1;
Console.WriteLine(comm.ExecuteScalar()); //打印另一个结果
}
catch
{
throw;
}
finally
{
conn.Close();
}一个结果是0(sqlparameter方式),另一个是12。谁能解释一下么?
1 B4 C4 D4 NULL NULL
2 B5 C5 D43 NULL NULL
3 B6 C6 D44 NULL NULL
4 B7 C7 D45 NULL NULL
5 B8 C8 D8 NULL NULL
6 B9 C9 D9 NULL NULL
7 B10 C10 D10 NULL NULL
8 B4 C41 D42 NULL NULL
9 B11 C11 D11 NULL NULL
10 B12 C12 D12 NULL NULL
11 B13 C13 D13 NULL NULL
12 B14 C14 D14 NULL NULL
相当于字符串中的 \0