数据库操作的封装

创建表

private void createTable(SQLiteDatabase db){
//创建表SQL语句
String stu_table="create table usertable(_id integer primary key autoincrement,sname text,snumber text)";
//执行SQL语句
db.execSQL(stu_table);
}

插入一条数据

private boolean insert(SQLiteDatabase db){
//实例化常量值
ContentValues cValue = new ContentValues();
//添加用户名
cValue.put("sname","xiaoming");
//添加密码
cValue.put("snumber","01005");
//调用insert()方法插入数据
db.insert("stu_table",null,cValue);
}

删除数据

private boolean delete(SQLiteDatabase db) {
//删除条件
String whereClause = "id=?";
//删除条件参数
String[] whereArgs = {String.valueOf(2)};
//执行删除
db.delete("stu_table",whereClause,whereArgs);
}

修改数据

private boolean update(SQLiteDatabase db) {
//实例化内容值 ContentValues values = new ContentValues();
//在values中添加内容
values.put("snumber","101003");
//修改条件
String whereClause = "id=?";
//修改添加参数
String[] whereArgs={String.valuesOf(1)};
//修改
db.update("usertable",values,whereClause,whereArgs);
}

查询指定数据

private void queryAll(SQLiteDatabase db){
Cursor cur = mysql.rawQuery("SELECT * FROM classes WHERE name = 'aab';", null);
if (cur != null)
{
while (cur.moveToNext())
{
address = cur.getString(4);
}
Toast.makeText(TimetableActivity.this, "0", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(TimetableActivity.this, "1", Toast.LENGTH_LONG).show();
}
cur.close();
}

查询数据

private void queryAll(SQLiteDatabase db) {
//查询获得游标
Cursor cursor = db.query ("usertable",null,null,null,null,null,null);

//判断游标是否为空
if(cursor.moveToFirst() {
//遍历游标
for(int i=0;i<cursor.getCount();i++){
cursor.move(i);
//获得ID
int id = cursor.getInt(0);
//获得用户名
String username=cursor.getString(1);
//获得密码
String password=cursor.getString(2);
//输出用户信息 System.out.println(id+":"+sname+":"+snumber);
}
}
}

删除数据

private void drop(SQLiteDatabase db){
//删除表的SQL语句
String sql ="DROP TABLE stu_table";
//执行SQL
db.execSQL(sql);
}