SQLite

发布时间：2020-12-12 23:51:42 所属栏目：百科来源：网络整理

导读：* SQL插入数据库的两种方法 ( 1 ) private void insertSQL() { // 获取一个SQLiteDatabase一个操作可操作数据库的对象 SQLiteDatabase db = mdbOpenHelper.getWritableDatabase(); // 调用execSQL()方法实现插入操作 db.execSQL("insert into stu_info value

* SQL插入数据库的两种方法

( 1 )

private void insertSQL() {
// 获取一个SQLiteDatabase一个操作可操作数据库的对象
SQLiteDatabase db = mdbOpenHelper.getWritableDatabase();
// 调用execSQL()方法实现插入操作
db.execSQL("insert into stu_info values(null,'xiaoqiang',22)");
db.execSQL("insert into stu_info values(null,'liuling',21)");
db.execSQL("insert into stu_info values(null,'wangyan','xiaosan',20)");
db.execSQL("insert into stu_info values(null,'zilong',23)");
// 数据库操作对象关闭数据库
db.close();

}

( 2 )

private void insertAPI() {
SQLiteDatabase db = mdbOpenHelper.getReadableDatabase();
ContentValues values = new ContentValues();
// values.put("_id",0);
values.put("stu_name","12345");
values.put("stu_age",102);
db.insert("stu_info",null,values);
values = new ContentValues();
// values.put("_id","23456");
values.put("stu_age",234);
db.insert("stu_info",values);
db.close();
}

* SQL查询数据库的两种方法

( 1 )

private void querySQL() {
SQLiteDatabase db = mdbOpenHelper.getReadableDatabase();
// 获取一个光标对象
Cursor cursor = db.rawQuery("select * from stu_info",null);
// 使用ArrayList保存多个HashMap数据对象
List<HashMap<String,Object>> stu_list = new ArrayList<HashMap<String,Object>>();
// 使用HashMap保存一条语句
HashMap<String,Object> map = null;
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
map = new HashMap<String,Object>();
// 通过“数据库”字段获取对应的数据
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
map.put("_id",_id);
String stu_Name = cursor.getString(cursor
.getColumnIndex("stu_name"));
map.put("stu_Name",stu_Name);
int stu_age = cursor.getInt(cursor.getColumnIndex("stu_age"));
map.put("stu_age",stu_age);
stu_list.add(map);
cursor.moveToNext();
Log.i("Yongke.pan","_id=" + _id + ",stu_Name=" + stu_Name
+ ",stu_age=" + stu_age);
}
cursor.close();
db.close();
}

( 2 )

private void queryAPI() {
SQLiteDatabase db = mdbOpenHelper.getReadableDatabase();

Cursor cursor = db
.query("stu_info",null);

// 使用ArrayList保存多个HashMap数据对象
List<HashMap<String,Object>>();
// 使用HashMap保存一条语句
HashMap<String,Object> map = null;
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
map = new HashMap<String,Object>();
// 通过“数据库”字段获取对应的数据
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
map.put("_id",_id);
// 通过“数据库”字段获取对应的数据
String stu_Name = cursor.getString(cursor
.getColumnIndex("stu_name"));
// 通过“数据库”字段获取对应的数据
map.put("stu_Name",stu_Name);
int stu_age = cursor.getInt(cursor.getColumnIndex("stu_age"));
map.put("stu_age",stu_age);
stu_list.add(map);
cursor.moveToNext();
Log.i("Yongke.pan",stu_Name=" + stu_Name
+ ",stu_age=" + stu_age);
}

cursor.close();
db.close();

}

* SQL更新的两种方法

( 1 )

private void updateSQL() {

SQLiteDatabase db = mdbOpenHelper.getReadableDatabase();
db.execSQL("update stu_info set stu_name='zidong',stu_age=30 where _id=4 or _id=9");
db.close();
}

( 2 )

private void updateAPI() {
SQLiteDatabase db = mdbOpenHelper.getReadableDatabase();
ContentValues values = new ContentValues();
values.put("stu_name","AAAA");
values.put("stu_age",1000);
db.update("stu_info",values,"_id<3",null);
db.close();

}

* SQL删除数据的两种方法

( 1 )

private void deleteSQL() {
db.execSQL("delete from stu_info where _id=4 or _id=9");
}

( 2 )

private void deleteAPI() {
db.delete("stu_info","_id>10",255)">}

（编辑：李大同）

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