我应该执行每个查询还是单个查询？

Question

I'm trying to Insert multiple records to table using ado.net , and print id inserted.

My code is like this:

List<string> listQuery = new List<string>()
{
    "INSERT INTO Students (Name) VALUES ('student1');SELECT @@Identity;",
    "INSERT INTO Students (Name) VALUES ('student2');SELECT @@Identity;",
    "INSERT INTO Students (Name) VALUES ('student3');SELECT @@Identity;",
};
using (SqlConnection connection = new SqlConnection(_connectionString))
{
    try
    {
        connection.Open();
        using (SqlCommand command = new SqlCommand())
        {
            command.Connection = connection;

            foreach (var myQuery in listQuery)
            {
                command.CommandText = myQuery;
                int id = Convert.ToInt32((decimal)command.ExecuteScalar());
                Console.WriteLine("Inserted: " + id);
            }
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }
    finally
    {
        //Close and dispose
        connection.Close();
    }
}

I wondering, whether should I execute every command like that? Or concatenate all query and execute just a times?.

If I should execute one times. How can i get all id of records inserted?

Answer 1

you can use the OUTPUT clause to return the identity id

INSERT INTO Students (Name)
OUTPUT  INSERTED.id
VALUES ('student1'), ('student2'), ('student3');

Answer 2

Don't go like this, and DON'T call database in ANY loop.

For resolving your problem, you should write stored procedure that take a DataTable as input of your student list ( tutorial ) or use JSON string as input. In that stored procedure you use OUTPUT clause to retrieve id: OUTPUT INSERTED.id . On C# code, you only need ExecuteReader to get all id.