終於在Wp7.1中加入了數據庫，使保存、查找、插入數據不再痛苦。在WP7中如果要做到這些，要麼使用XML自已實現，要麼使用第三方數據庫，但是第三方數據庫要麼性能不好，要麼佔用空間太大，要麼收費，現在總算有原生的本地數據庫了。
1 這個本地數據庫，不能直接支持Transact-SQL，需要通過LINQ to SQL 對象模型作爲Proxy來操作數據庫，爲此引入了一個新的類System.Data.Linq.DataContext。這與windows mobile上的SQL CE有了很大的差別。
2． LINQ to SQL
在Windows phone中，LINQ to SQL既不能直接支持執行Data Definition Language(DDL)也不支持Data Modeling Language(DML)，另外也不能直接訪問ADO.NET。只能支持Microsoft SQL Server Compact Edition (SQL CE)的數據類型。並且需要通過DataContext方式來操來數據庫。
3． 支持的數據類型
|
數據類型 |
描述 |
|
bigint |
Integer (whole number) data from –2^63 (–9,223,372,036,854,775,808) through 2^63–1 (9,223,372,036,854,775,807). Storage size is 8 bytes. |
|
integer |
Integer (whole number) data from –2^31 (–2,147,483,648) through 2^31–1 (2,147,483,647). Storage size is 4 bytes. |
|
smallint |
Integer data from –32,768 to 32,767. Storage size is 2 bytes. |
|
tinyint |
Integer data from 0 to 255. Storage size is 1 byte. |
|
bit |
Integer data with a value of either 1 or 0. Storage size is 1 bit. |
|
numeric (p, s) Synonyms: decimal(p,s) and dec (p,s) |
Fixed-precision and scale-numeric data from –10^38+1 through 10^38–1. The p variable specifies precision and can vary between 1 and 38. The s variable specifies scale and can vary between 0 and p. Storage size is 19 bytes. |
|
money |
Monetary data values from (–2^63/10000) (–922,337,203,685,477.5808) through 2^63–1 (922,337,203,685,477.5807), with accuracy to a ten-thousandth of a monetary unit. Storage size is 8 bytes. |
|
float |
Floating point number data from –1.79E +308 through 1.79E+308 Storage size is 8 bytes. |
|
real |
Floating precision number data from –3.40E+38 through 3.40E+38. Storage size is 4 bytes. |
|
datetime |
Date and time data from January 1, 1753, to December 31, 9999, with an accuracy of one three-hundredth second, or 3.33 milliseconds. Values are rounded to increments of .000, .003, or .007 milliseconds. Stored as two 4-byte integers. The first 4 bytes store the number of days before or after the base date, January 1, 1900. The base date is the system's reference date. Values for datetime earlier than January 1, 1753, are not permitted. The other 4 bytes store the time of day represented as the number of milliseconds after midnight. Seconds have a valid range of 0–59. Format Example yyyy/mm/dd hh:mm:ss 1947/08/15 03:33:20 mm/dd/yyyy hh:mm:ss 04/15/1947 03:33:20 dd mmm yyyy hh:mm:ss 15 Jan 1947 03:33:20 dd mmmm yyyy h:mm:ss 15 January 1947 03:33:20 |
|
national character(n) Synonym:nchar(n) |
Fixed-length Unicode data with a maximum length of 4000 characters. Default length = 1. Storage size, in bytes, is two times the number of characters entered. |
|
national character varying(n) Synonym:nvarchar(n) |
Variable-length Unicode data with a length of 1 to 4000 characters. Default length = 1. Storage size, in bytes, is two times the number of characters entered. |
|
ntext⊃1; |
Variable-length Unicode data with a maximum length of (2^30–2)/2 (536,870,911) characters. Storage size, in bytes, is two times the number of characters entered. Note ntext is no longer supported in string functions. |
|
nchar |
Fixed-length Unicode character data of n characters. n must be a value from 1 through 4,000. The storage size is two times n bytes. |
|
binary(n) |
Fixed-length binary data with a maximum length of 8000 bytes. Default length = 1. Storage size is fixed, which is the length in bytes declared in the type. |
|
varbinary(n) |
Variable-length binary data with a maximum length of 8000 bytes. Default length = 1. Storage size varies. It is the length of the value in bytes. |
|
image⊃1; |
Variable-length binary data with a maximum length of 2^30–1 (1,073,741,823) bytes. Storage is the length of the value in bytes. |
|
uniqueidentifier |
A globally unique identifier (GUID). Storage size is 16 bytes. |
|
IDENTITY [(s, i)] |
This is a property of a data column, not a distinct data type. Only data columns of the integer data types can be used for identity columns. A table can have only one identity column. A seed and increment can be specified and the column cannot be updated. s (seed) = starting value i(increment) = increment value |
|
ROWGUIDCOL |
This is a property of a data column, not a distinct data type. It is a column in a table that is defined by using the uniqueidentifier data type. A table can have only one ROWGUIDCOL column. |
|
Timestamp/rowversion |
This is an automatically generated unique binary number. Storage size is 8 bytes. |
⊃1;在SQL Server Compact 4.0中，當Ntext 和 image 數據超過256 bytes 時將會保存到一個新的數據頁。這會影響到數據庫的密度，因爲SQL Server Compact 4.0 數據庫是按頁方式面不是按字節方式來壓縮的。
4． 創建工程
新建一個Windows Phone工程，最好是MVVM工程，也就是選擇新建工程中的Windows Phone Databound Application 模板直接生成或者手工創建MVVM工程。創建好後，將System.Data.Linq命名空間引入到工程。這個命名空間所在位置\Program Files\Reference Assemblies\Microsoft\Framework\Silverlight\v4.0\Profile\WindowsPhone71中。
5． 創建數據庫
新建一個類繼承System.Data.Linq.DataContext類，這樣就可以用這個類來控制數據庫了。
01 |
public class MyDataContext : DataContext
|
02 |
|
03 |
{
|
04 |
|
05 |
public const string ConnectionStr = "Data Source=isostore:/MyDB.sdf";
|
06 |
|
07 |
public Table<MYTABLE> Rows;
|
08 |
|
09 |
public MyDataContext()
|
10 |
|
11 |
: base(ConnectionStr)
|
12 |
|
13 |
{
|
14 |
|
15 |
|
16 |
}
|
17 |
|
18 |
}</MYTABLE> |
在這個類中同時創建數據庫表類。
001 |
[Table]
|
002 |
|
003 |
public class MyTable : INotifyPropertyChanged, INotifyPropertyChanging
|
004 |
|
005 |
{
|
006 |
|
007 |
private int _index;
|
008 |
|
009 |
[Column(IsPrimaryKey = true, CanBeNull = false, IsDbGenerated = true, DbType = "INT NOT NULL Identity", AutoSync=AutoSync.OnInsert)]
|
010 |
|
011 |
public int Index
|
012 |
|
013 |
{
|
014 |
|
015 |
get
|
016 |
|
017 |
{
|
018 |
|
019 |
return _index;
|
020 |
|
021 |
}
|
022 |
|
023 |
set
|
024 |
|
025 |
{
|
026 |
|
027 |
if (_index != value)
|
028 |
|
029 |
{
|
030 |
|
031 |
NotifyPropertyChanging("Index");
|
032 |
|
033 |
_index = value;
|
034 |
|
035 |
NotifyPropertyChanged("Index");
|
036 |
|
037 |
}
|
038 |
|
039 |
|
040 |
|
041 |
}
|
042 |
|
043 |
}
|
044 |
|
045 |
|
046 |
|
047 |
private string _name;
|
048 |
|
049 |
[Column]
|
050 |
|
051 |
public string Name
|
052 |
|
053 |
{
|
054 |
|
055 |
get
|
056 |
|
057 |
{
|
058 |
|
059 |
return _name;
|
060 |
|
061 |
}
|
062 |
|
063 |
set
|
064 |
|
065 |
{
|
066 |
|
067 |
NotifyPropertyChanging("Name");
|
068 |
|
069 |
_name = value;
|
070 |
|
071 |
NotifyPropertyChanged("Name");
|
072 |
|
073 |
}
|
074 |
|
075 |
}
|
076 |
|
077 |
|
078 |
|
079 |
private String _gen;
|
080 |
|
081 |
[Column]
|
082 |
|
083 |
public String Gen
|
084 |
|
085 |
{
|
086 |
|
087 |
get
|
088 |
|
089 |
{
|
090 |
|
091 |
return _gen;
|
092 |
|
093 |
}
|
094 |
|
095 |
set
|
096 |
|
097 |
{
|
098 |
|
099 |
NotifyPropertyChanging("Gen");
|
100 |
|
101 |
_gen = value;
|
102 |
|
103 |
NotifyPropertyChanged("Gen");
|
104 |
|
105 |
}
|
106 |
|
107 |
}
|
108 |
|
109 |
|
110 |
|
111 |
private int _age;
|
112 |
|
113 |
[Column]
|
114 |
|
115 |
public int Age
|
116 |
|
117 |
{
|
118 |
|
119 |
get
|
120 |
|
121 |
{
|
122 |
|
123 |
return _age;
|
124 |
|
125 |
}
|
126 |
|
127 |
set
|
128 |
|
129 |
{
|
130 |
|
131 |
NotifyPropertyChanging("Age");
|
132 |
|
133 |
_age = value;
|
134 |
|
135 |
NotifyPropertyChanged("Age");
|
136 |
|
137 |
}
|
138 |
|
139 |
}
|
140 |
|
141 |
|
142 |
|
143 |
#region INotifyPropertyChanged Members
|
144 |
|
145 |
|
146 |
|
147 |
public event PropertyChangedEventHandler PropertyChanged;
|
148 |
|
149 |
|
150 |
|
151 |
private void NotifyPropertyChanged(string propertyName)
|
152 |
|
153 |
{
|
154 |
|
155 |
if (PropertyChanged != null)
|
156 |
|
157 |
{
|
158 |
|
159 |
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
|
160 |
|
161 |
}
|
162 |
|
163 |
}
|
164 |
|
165 |
|
166 |
|
167 |
#endregion
|
168 |
|
169 |
|
170 |
|
171 |
#region INotifyPropertyChanging Members
|
172 |
|
173 |
|
174 |
|
175 |
public event PropertyChangingEventHandler PropertyChanging;
|
176 |
|
177 |
|
178 |
|
179 |
private void NotifyPropertyChanging(string propertyName)
|
180 |
|
181 |
{
|
182 |
|
183 |
if (PropertyChanging != null)
|
184 |
|
185 |
{
|
186 |
|
187 |
PropertyChanging(this, new PropertyChangingEventArgs(propertyName));
|
188 |
|
189 |
}
|
190 |
|
191 |
}
|
192 |
|
193 |
|
194 |
|
195 |
#endregion
|
196 |
|
197 |
} |
6． 操作數據庫
新建一個ViewModel類，在這個類中實現數據庫的操作。在這個類中實現了對數據的選擇、保存、更新和刪除。在對數據庫的操作因爲不能直接使用Transact_SQL,所以操作都是通過LINQ來完成的。
01 |
MyDataContext _DB;
|
02 |
|
03 |
public void SelectData()
|
04 |
{
|
05 |
if (IsAddedToDB)
|
06 |
{
|
07 |
if (_DB.DatabaseExists())
|
08 |
{
|
09 |
IEnumerator<MYTABLE> enumerator = _DB.Rows.GetEnumerator();
|
10 |
while (enumerator.MoveNext())
|
11 |
{
|
12 |
this.Items.Add(enumerator.Current);
|
13 |
}
|
14 |
IsAddedToDB = false;
|
15 |
}
|
16 |
}
|
17 |
}
|
18 |
public bool SaveData(MyTable table)
|
19 |
{
|
20 |
try
|
21 |
{
|
22 |
this.Items.Add(table);
|
23 |
_DB.Rows.InsertOnSubmit(table);
|
24 |
_DB.SubmitChanges();
|
25 |
}
|
26 |
catch (Exception e)
|
27 |
{
|
28 |
return false;
|
29 |
}
|
30 |
return true;
|
31 |
}
|
32 |
|
33 |
public bool DeleteData(MyTable table)
|
34 |
{
|
35 |
try
|
36 |
{
|
37 |
if (_DB.DatabaseExists())
|
38 |
{
|
39 |
_DB.Rows.DeleteOnSubmit(table);
|
40 |
_DB.SubmitChanges();
|
41 |
this.Items.Remove(table);
|
42 |
}
|
43 |
}
|
44 |
catch (Exception e)
|
45 |
{
|
46 |
return false;
|
47 |
}
|
48 |
return true;
|
49 |
|
50 |
}
|
51 |
|
52 |
|
53 |
|
54 |
public bool UpdateData(MyTable source, MyTable dest)
|
55 |
{
|
56 |
try
|
57 |
{
|
58 |
var tables = from item in this.Items where (int)item.Index == source.Index select item;
|
59 |
|
60 |
foreach (MyTable mt in tables)
|
61 |
{
|
62 |
mt.Name = dest.Name;
|
63 |
mt.Age = dest.Age;
|
64 |
mt.Gen = dest.Gen;
|
65 |
|
66 |
break;
|
67 |
|
68 |
}
|
69 |
|
70 |
MyTable table = _DB.Rows.GetOriginalEntityState(source);
|
71 |
table.Name = dest.Name;
|
72 |
table.Age = dest.Age;
|
73 |
table.Gen = dest.Gen;
|
74 |
_DB.SubmitChanges();
|
75 |
}
|
76 |
catch (Exception e)
|
77 |
{
|
78 |
return false;
|
79 |
}
|
80 |
|
81 |
return true;
|
82 |
}</MYTABLE> |
以下是運行效果：
