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,sans-serif; font-size:14px; line-height:25px">claose() 当关闭数据库时,sans-serif; font-size:14px; line-height:25px">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",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)};

db.update("表名",cv,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. public class DatabaseAdapter{
9. private static final String DB_NAME = "Test.db"; //数据库名
10. private static final int DB_VERSION = 1; //数据库版本
11. private static final String DB_TABLE = "my_order"; //表名
12. private static final String KEY_ID = "_id"; //id
13. private static final String KEY_ORDER_ID = "order_id"; //订单号
14. private static final String KEY_TYPE = "_type"; //订单类型
15. private static final String KEY_STATE = "_state"; //订单状态
16. private Context context;
17. private DatabaseHelper mDatabaseHelper;
18. private SQLiteDatabase mSQLiteDatabase;
19. private static class DatabaseHelper extends SQLiteOpenHelper{
20. //创建数据库语句
21. private static final String DB_CREAT = "CREATE TABLE "
22. + DB_TABLE
23. + " (" + KEY_ID + " INTEGER PRIMARY KEY,"
24. + KEY_ORDER_ID + " TEXT,250); margin:0px 0px 0px 38px; padding-left:10px; padding-right:0px; font-size:1em; padding-top:0px"> + KEY_TYPE + " INTEGER,250); margin:0px 0px 0px 38px; padding-left:10px; padding-right:0px; font-size:1em; padding-top:0px"> + KEY_STATE + " INTEGER)";
25. public DatabaseHelper(Context context) {
26. super(context,DB_NAME,null,DB_VERSION);
27. }
28. @Override
29. public void onCreate(SQLiteDatabase db) {
30. // TODO Auto-generated method stub
31. db.execSQL(DB_CREAT);
32. public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {
33. db.execSQL("DROP TABLE IF EXISTS "+DB_TABLE);
34. onCreate(db);
35. public DatabaseAdapter(Context context) {
36. this.context = context;
37. //开启
38. public void open() {
39. mDatabaseHelper = new DatabaseHelper(context);
40. mSQLiteDatabase = mDatabaseHelper.getWritableDatabase();
41. //关闭
42. public void close() {
43. mSQLiteDatabase.close();
44. mDatabaseHelper.close();
45. //增
46. public long insertData(String orderId,int type) {
47. ContentValues values = new ContentValues();
48. values.put(KEY_ORDER_ID,orderId);
49. values.put(KEY_TYPE,type);
50. values.put(KEY_STATE,Config.STATE_APPLY);
51. long id = mSQLiteDatabase.insert(DB_TABLE,KEY_ID,values);
52. return id;
53. //删
54. public boolean deleteData(Context context,long id) {
55. boolean delete = mSQLiteDatabase.delete(DB_TABLE,KEY_ID + "=" +id,null)>0;
56. return delete;
57. //改
58. public boolean updateData(long id,int state) {
59. ""+state);
60. boolean update = mSQLiteDatabase.update(DB_TABLE,values,250); margin:0px 0px 0px 38px; padding-left:10px; padding-right:0px; font-size:1em; padding-top:0px"> return update;
61. //查
62. public Cursor fetchData(String selection) {
63. Cursor mCursor = mSQLiteDatabase.query(DB_TABLE, new String[]{KEY_ID,KEY_ORDER_ID,KEY_TYPE,KEY_STATE},null);
64. if(mCursor != null)
65. mCursor.moveToFirst();
66. return mCursor;
67. }

（编辑：李大同）

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