C#中字符串插值($) 和 逐字字符串(@)的使用

string name = "Alice";
string message = $"Hello, {name}!"; // 输出：Hello, Alice!

string sql = @"
    SELECT *
    FROM Users
    WHERE Id = 1";

string strsql = $@"
    INSERT INTO System 
    (PID, Level, SortOrder, Name, remark, CreatedTime, ModifiedTime)
    VALUES (...)
";

remark= 'admin/home'

remark= NULL

INSERT INTO System
(PID, Level, SortOrder, Name, remark, CreatedTime, ModifiedTime)
VALUES (
    1,
    3,
    1,  -- 假设 GetNextSortOrder(parentId) 返回 1
    'Admin Page',
    'admin/home',
    GETDATE(),
    GETDATE()
)

using (var cmd = new SqlCommand(
    @"INSERT INTO System 
       (PID, Level, SortOrder, Name, remark, CreatedTime, ModifiedTime)
       VALUES (@PID, @Level, @SortOrder, @Name, @remark, GETDATE(), GETDATE())", 
    connection))
{
    cmd.Parameters.AddWithValue("@PID", parentId ?? (object)DBNull.Value);
    cmd.Parameters.AddWithValue("@Level", level);
    cmd.Parameters.AddWithValue("@SortOrder", GetNextSortOrder(parentId));
    cmd.Parameters.AddWithValue("@Name", editForm.NodeName);
    cmd.Parameters.AddWithValue("@remark", level == 3 ? editForm.Target : (object)DBNull.Value);
    cmd.ExecuteNonQuery();
}