安卓日记——sqlite用法

sqlite需要用到SQLiteOpenHelper
首先新建一个类继承自SQLiteOpenHelper
重写它的而方法
在构造方法（此处类名为DbOpenHelper）中可以只留下context参数。
name和version可以提出来，写成静态，因为通常用的都是相同的
但如果有多个表时就就要把name放进去了

public DbOpenHelper(Context context) {
super(context, name, null, version);
// TODO Auto-generated constructor stub
}

第三个（即factory改为null）
在oncreate里添加如下代码创建表

String sql="create table person(id integer primary key autoincrement,name varchar(64),address varchar(64),sex varchar(8))";
arg0.execSQL(sql);

id为自增值

String sql="insert into person(name,address,sex) values(?,?,?)";

Object[] params={"张三","北京","男"};
DbOpenHelper helper;
database=helper.getWritableDatabase();database.execSQL(sql, params);

String sql="update person set name = ?,address = ?,sex = ? where id =?";

Object[] params={"acely","nope","male",1};

DbOpenHelper helper;

database=helper.getWritableDatabase();database.execSQL(sql,params);

3.删除（此处以删除id为1为例）

String sql="delete from person1 where id =?";

DbOpenHelper helper;
Object[] params={1};
database=helper.getWritableDatabase();database.execSQL(sql,params);

4.查询单个或多个（以查询id为1的为例）

Mapmap=new HashMap();

String sql="select * from person where id=?";
database=helper.getWritableDatabase();

String[] selectiOnArgs={"1"};Cursor cursor=database.rawQuery(sql, selectionArgs);int colums=cursor.getColumnCount();while (cursor.moveToNext()) {for (int i = 0; i 

SQLiteDatabase database=null;

List>list=new ArrayList>();
try {
String sql="select * from person";
database=helper.getWritableDatabase();
Cursor cursor=database.rawQuery(sql, selectionArgs);
int colums=cursor.getColumnCount();
while (cursor.moveToNext()) {
Mapmap=new HashMap();
for (int i = 0; i String cols_name=cursor.getColumnName(i);
String cols_value=cursor.getString(cursor.getColumnIndex(cols_name));
if (cols_value==null) {
cols_value="";
}
map.put(cols_name, cols_value);
}
list.add(map);

}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if (database!=null) {
database.close();
}
}