SQLite

SQLite
2个主要的类
A)__SQLiteOpenHelper
这个类是一个抽象类
实现他的类必须包含一个构造方法: public **(Context context,表的名字,CursorFactory,版本){spuer(**,**,**,**)}
参数注意:
version(版本):必须是大于0的整数

方法:
getReadableDatabase() 返回:可读的SQLiteDatabase
getWritableDatabase() 返回:可写的SQLiteDatabase
onCreate(SQLiteDatabase db) 第一次调用这个类的时候会调用 ,是个回调函数
onUpgradel(SQLiteDatabase db,int oldVersion,int new Version) 升级数据库的时候调用,是个回调函数
claose() 当关闭数据库时,是个回调函数

B)__SQLiteDatabase SQLite操作的类

实例:

//Databasehelper 是一个继承自SQLiteOpenHelper的类
Databasehelper dbHeper = new DatabaseHelper(上下文环境,"数据库名称",null,版本);
SQLiteDatabase db = dbHeper.getReadableDatabase();//或 getWritableDatabase()

//查询 返回 Cursor(一个游标类型,可以用 curosr.moveToNext()执行下一步操作)
Curosr cu = db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
while(cu.moveToNext()){
String name =cu.getString(cu.getColumnINdex("列名"));
}

//增加
ContentValues cv = new ContentValues();
cv.put("列名","值");
long row = db.insert("表名",null,cv);

//删除
String where ="ID = ?";
String [] whereValue = {Integer.toString(id)};//这里如果where有多少个? 就要有多少个值
db.delete("表名",where,whereValue);

//修改
String where ="id =?";
String [] whereValue = {Integer.toString(id)};
ContentValues cv = new ContentValues();
cv.put("列名","要修改成什么值");
db.update("表名",cv,where,whereValue);

1. import android.content.ContentValues;
2. import android.content.Context;
3. import android.database.Cursor;
4. import android.database.sqlite.SQLiteDatabase;
5. import android.database.sqlite.SQLiteOpenHelper;
6. import android.util.Log;
8. publicclass DatabaseAdapter{
10. privatestaticfinal String DB_NAME ="Test.db";//数据库名
11. privatestaticfinalint DB_VERSION =1;//数据库版本
13. privatestaticfinal String DB_TABLE ="my_order";//表名
14. privatestaticfinal String KEY_ID ="_id";//id
15. privatestaticfinal String KEY_ORDER_ID ="order_id";//订单号
16. privatestaticfinal String KEY_TYPE ="_type";//订单类型
17. privatestaticfinal String KEY_STATE ="_state";//订单状态
19. private Context context;
20. private DatabaseHelper mDatabaseHelper;
21. private SQLiteDatabase mSQLiteDatabase;
23. privatestaticclass DatabaseHelperextends SQLiteOpenHelper{
24. //创建数据库语句
25. privatestaticfinal String DB_CREAT ="CREATE TABLE "
26. + DB_TABLE
27. + " (" + KEY_ID +" INTEGER PRIMARY KEY,"
28. + KEY_ORDER_ID + " TEXT,"
29. + KEY_TYPE + " INTEGER,"
30. + KEY_STATE + " INTEGER)";
32. public DatabaseHelper(Context context) {
33. super(context, DB_NAME,null , DB_VERSION);
34. }
35. @Override
36. publicvoid onCreate(SQLiteDatabase db) {
37. // TODO Auto-generated method stub
38. db.execSQL(DB_CREAT);
39. }
40. @Override
41. publicvoid onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {
42. // TODO Auto-generated method stub
43. db.execSQL("DROP TABLE IF EXISTS "+DB_TABLE);
44. onCreate(db);
45. }
46. }
48. public DatabaseAdapter(Context context) {
49. this.context = context;
50. }
51. //开启
52. publicvoid open() {
53. mDatabaseHelper = new DatabaseHelper(context);
54. mSQLiteDatabase = mDatabaseHelper.getWritableDatabase();
55. }
56. //关闭
57. publicvoid close() {
58. mSQLiteDatabase.close();
59. mDatabaseHelper.close();
60. }
62. //增
63. publiclong insertData(String orderId,int type) {
64. ContentValues values = new ContentValues();
65. values.put(KEY_ORDER_ID, orderId);
66. values.put(KEY_TYPE, type);
67. values.put(KEY_STATE, Config.STATE_APPLY);
68. long id = mSQLiteDatabase.insert(DB_TABLE, KEY_ID, values);
69. return id;
70. }
71. //删
72. publicboolean deleteData(Context context,long id) {
73. boolean delete = mSQLiteDatabase.delete(DB_TABLE, KEY_ID +"=" +id,null)>0;
74. return delete;
75. }
76. //改
77. publicboolean updateData(long id,int state) {
78. ContentValues values = new ContentValues();
79. values.put(KEY_STATE, ""+state);
80. boolean update = mSQLiteDatabase.update(DB_TABLE, values, KEY_ID +"=" +id,null)>0;
81. return update;
82. }
83. //查
84. public Cursor fetchData(String selection) {
85. Cursor mCursor = mSQLiteDatabase.query(DB_TABLE, new String[]{KEY_ID, KEY_ORDER_ID, KEY_TYPE, KEY_STATE}, selection,null,null,null,null);
86. if(mCursor !=null)
87. mCursor.moveToFirst();
88. return mCursor;
89. }
90. }