数据模型和数据访问类以及属性扩展和泛型集合

 1 public class Car
 2     {
 3         SqlConnection conn = null;
 4         SqlCommand com = null;
 5         public Car()
 6         {
 7             conn = new SqlConnection("server=.;database=ADOlianxi0425;user=sa;pwd=123;");
 8             com = conn.CreateCommand();
 9         }
10         private int _ids;
11 
12         public int Ids
13         {
14             get { return _ids; }
15             set { _ids = value; }
16         }
17         private string _code;
18 
19         public string Code
20         {
21             get { return _code; }
22             set { _code = value; }
23         }
24         private string _name;
25 
26         public string Name
27         {
28             get { return _name; }
29             set { _name = value; }
30         }
31         private string _brand;
32 
33         public string Brand
34         {
35             get { return _brand; }
36             set { _brand = value; }
37         }
38         private DateTime _time;
39 
40         public DateTime Time
41         {
42             get { return _time; }
43             set { _time = value; }
44         }
45         private decimal _oil;
46 
47         public decimal Oil
48         {
49             get { return _oil; }
50             set { _oil = value; }
51         }
52         private int _powers;
53 
54         public int Powers
55         {
56             get { return _powers; }
57             set { _powers = value; }
58         }
59         private int _exhaust;
60 
61         public int Exhaust
62         {
63             get { return _exhaust; }
64             set { _exhaust = value; }
65         }
66         private decimal _price;
67 
68         public decimal Price
69         {
70             get { return _price; }
71             set { _price = value; }
72         }
73         private string _pic;
74 
75         public string Pic
76         {
77             get { return _pic; }
78             set { _pic = value; }
79         }
80 
81    }

 1 public List<Car> select(string c, string d, string e)
 2         {
 3             List<Car> list = new List<Car>();//定义一个泛型集合，里面放的类型是前面写的数据结构类
 4             b.CommandText = "select * from car where name like @name and oil like @oil and powers like @powers";
 5             b.Parameters.Clear();
 6             b.Parameters.Add("@name", "%" + c + "%");
 7             b.Parameters.Add("@oil", "%" + d + "%");
 8             b.Parameters.Add("@powers", "%" + e + "%");
 9             a.Open();
10             SqlDataReader f = b.ExecuteReader();
11             if (f.HasRows)
12             {
13                 while (f.Read())
14                 {
15                     Car cc = new Car();//将表中的每行数据查询出来然后全部转换成定义好的数据结构类
16                     cc.Ids = Convert.ToInt32(f["ids"]);
17                     cc.Code = f["code"].ToString();
18                     cc.Name = f["name"].ToString();
19                     cc.Brand = f["brand"].ToString();
20                     cc.Time = Convert.ToDateTime(f["time"]);
21                     cc.Oil = Convert.ToDecimal(f["oil"]);
22                     cc.Powers = Convert.ToInt32(f["powers"]);
23                     cc.Exhaust = Convert.ToInt32(f["exhaust"]);
24                     cc.Price = Convert.ToDecimal(f["price"]);
25                     cc.Pic = f["pic"].ToString();
26 
27                     list.Add(cc);//用上面定义好的泛型集合存放数据库表中的所有数据
28                 }
29             }
30             a.Close();
31             return list;
32         }

 1 /// <summary>
 2         /// 写成方法用起来一样，没有差别，memo是brand表中的数据，brand表中的brand_code是car表中brand的外键。
 3         /// </summary>
 4         public string memo
 5         {
 6             get
 7             {
 8                 string JJ = "";
 9 
10                 com.CommandText = "select * from brand where brand_code = @brand";
11                 com.Parameters.Clear();
12                 com.Parameters.Add("@brand", _brand);
13                 conn.Open();
14                 SqlDataReader dr = com.ExecuteReader();
15                 if (dr.HasRows)
16                 {
17                     dr.Read();
18                     JJ = dr["brand_name"].ToString();
19                 }
20                 conn.Close();
21                 return JJ;
22             }
23         }