sq数据库增删改查
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private ListView lv;
private StudentDao sd;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv=(ListView)findViewById(R.id.lv);
sd = new StudentDao(this);
}
public void add(View v){
sd.aa();
}
public void select(View v){
List<Person> select = sd.select();
lv.setAdapter(new ArrayAdapter<Person>(this, android.R.layout.simple_list_item_1, select));
}
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
public class MyOpenHelper extends SQLiteOpenHelper {
public MyOpenHelper(Context context) {
super(context, "school3.db", null, 3); //1 school3.db存在,onCreate不执行; 2 添加表
}
// 数据第一次创建的时候,onCreate才会执行
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table person (id integer primary key,sname varchar(20),sage int,sex varchar(2) not null)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
switch (newVersion) {
case 2:
db.execSQL("create table teacher (id integer primary key,tname varchar(20),tage int,tsex varchar(2) not null)");
db.execSQL("insert into teacher values (1,'张二龙老师',20,'男')");
break;
case 3:
db.execSQL("alter table teacher add salary int default 1200"); //修改表结构 添加列
default:
break;
}
}
}
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
public class StudentDao {
MyOpenHelper mo;
SQLiteDatabase db; //db对象执行增删改查
//获取OpenHelper
public StudentDao(Context ctx){
mo=new MyOpenHelper(ctx);
db=mo.getWritableDatabase();
}
//固定的值
public void aa() {
// 添加数据
db.execSQL("insert into person values (null,'张三',12,'男')"); // insert
// into
// person
// (要添加的列)
// values
// (列的值);
db.execSQL("insert into person values (null,?,?,?)", new Object[] {
"李四", 20, "女" });
// 内容值
ContentValues values = new ContentValues();
values.put("sname", "v张三");
values.put("sage", 50);
values.put("sex", "女");
// 不用sql
db.insert("person", null, values); // 底层封装sql语句 insert into person
}
/**
* 查询
* @return
*/
public List<Person> select() {
List<Person> ps = new ArrayList<Person>(); // size=0
Cursor query = db.rawQuery("select * from person", null); // 执行查询,必须接受返回值
while (query.moveToNext()) { // 指向一行数据---->一个java对象
Person p = new Person(query.getInt(0), query.getString(1),
query.getInt(2), query.getString(3));
ps.add(p);
}
//
return ps;
}
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
public class Person implements Serializable{
private int id;
private String sname;
private int sage;
private String sex;
@Override
public String toString() {
return "Person [id=" + id + ", sname=" + sname + ", sage=" + sage
+ ", sex=" + sex + "]";
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public int getSage() {
return sage;
}
public void setSage(int sage) {
this.sage = sage;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Person() {
super();
}
public Person(int id, String sname, int sage, String sex) {
super();
this.id = id;
this.sname = sname;
this.sage = sage;
this.sex = sex;
}
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context=".MainActivity" >
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="add"
android:text="添加" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="update"
android:text="修改" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="del"
android:text="删除" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="select"
android:text="查询" />
<ListView
android:id="@+id/lv"
android:layout_width="match_parent"
android:layout_height="match_parent"
></ListView>
</LinearLayout>
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