Android中数据库的基本操作

1、MyOpenHelper类

public class MyOpenHelper extends SQLiteOpenHelper{    public MyOpenHelper(Context context) {        super(context, "test.db", null, 1);    }    @Override    public void onCreate(SQLiteDatabase db) {        //聊天的数据库        db.execSQL("create table math_message(_id integer primary key autoincrement, name char(10),msg char(20), path char(20),time char(20))");        System.out.println("数据库被创建了");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        System.out.println("数据库升级了");    }}

2、插入数据

public void insertApi(String name, String path) {        //把要插入的数据全部封装至ContentValues对象        MyOpenHelper oh = new MyOpenHelper(context);        SQLiteDatabase db = oh.getWritableDatabase();        ContentValues values = new ContentValues();        values.put("name", name);//name列值        values.put("path", path);//path列值        db.insert("head", null, values);//head表名        db.close();    }

或者

//person 表名 插入数据为"小志", 14000, "13888"db.execSQL("insert into person (name, salary, phone)values(?, ?, ?)", new Object[]{"小志", 14000, "13888"});

3、查询表的所有数据

public void chaxun() {        //把数据库的数据查询出来        MyOpenHelper oh = new MyOpenHelper(this);        SQLiteDatabase db = oh.getWritableDatabase();        //head表名        Cursor cursor = db.query("head", null, null, null, null, null, null, null);        while (cursor.moveToNext()) {            String _id = cursor.getString(0);            String name = cursor.getString(1);            String path = cursor.getString(2);            LocalHead q = new LocalHead(_id, name, path);            Localhead.add(q);        }    }

或者

//从person表查询name和salary Cursor cursor = db.rawQuery("select name, salary from person", null);        while(cursor.moveToNext()){            //通过列索引获取列的值            String name = cursor.getString(cursor.getColumnIndex("name"));            String salary = cursor.getString(1);            System.out.println(name + ";" + salary);        }

5、删除

//删除person 表中name为呵呵的行db.execSQL("delete from person where name = ?", new Object[]{"呵呵"});

或者

//i为成功删除的行数 person为表名   int i = db.delete("person", "name = ? and _id = ?", new String[]{"哈哈", "3"});

6、更新数据

//在person 表中将name为哈哈更新phone为186666db.execSQL("update person set phone = ? where name = ?", new Object[]{186666, "哈哈"});

或者

ContentValues values = new ContentValues();values.put("salary", 26000);int i = db.update("person", values, "name = ?", new String[]{"哈哈"});

7、LocalHead 类

public class LocalHead {    private String _id;    private String name;    private String path;    public String get_id() {        return _id;    }    public void set_id(String _id) {        this._id = _id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPath() {        return path;    }    public void setPath(String path) {        this.path = path;    }    public LocalHead(String _id, String name, String path) {        super();        this._id = _id;        this.name = name;        this.path = path;    }}