Android Studio创建sqlite数据库及SQL语句的执行_阿喵酱ovo_android studio 创建sqlite

irpas 02-07 1556

Android中数据库的创建 ? 数据库类：SQLite Database ? 数据库帮助类：SQLiteOpenHelper 方法一 ? db = SQLiteDatabase.openOrCreateDatabase(DATABASE_NAME, Context.MODE_PRIVATE, null)

方法二 ? db = getContext().openOrCreateDatabase (DATABASE NAME, Context.MODE PRIVATE, null) 方法三 ? db = SQLiteOpenHelper.getWritableDatabase() ? db = SQLiteOpenHelper.getReableDatabase()

执行SQL语句，这里是直接执行 ? String sq| = "insert into tableName values (" 小华", "111");"; ? db.execSQL(sql);

Android中封装好的SQL语句执行方法 ?增加一条数据 db.insert(TABLE_ NAME, null, values); ?删除一条数据 db.delete(TABLE_ NAME, selection, selectionArgs) ?修改一条数据 db.update(TABLE_ NAME,values, selection,selectionArgs); ?查询一条数据 db.query( ????????TABLE_NAME,???????? // The table to query ????????projection,????????//The array of columns to return (pass null to get all) ????????selection,????????//?The columns for the WHERE clause ????????selectionArgs,????????// The values for the WHERE clause ????????null,????????????????// don't group the rows ? ? ? ? null,? ? ? ? ? ? ? ? //?don't filter by row groups ????????sortOrder? ? ? ?//?The sort order

????????);

下面是我写的创建数据库及简单的增删改查。

public class MySQLiteOpenHelper extends SQLiteOpenHelper { private static final String DB_NAME="mySQLite.db";//数据库名字 private static final String TABLE_NAME_STUDENT="student";//表的名字 //创建表 private static final String CREATE_TABLE_SQL="create table "+TABLE_NAME_STUDENT +"(id integer primary key autoincrement,name text,number text,gender text,score text )"; public MySQLiteOpenHelper(Context context){ super(context,DB_NAME,null,1); } @Override public void onCreate(SQLiteDatabase db) { //onCreate是创建数据库方法 db.execSQL(CREATE_TABLE_SQL); } //这个方法是数据库升级的时候使用到的，因为我没有用到，所以就没有写 @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } //添加数据 public long insertData(Student student){ SQLiteDatabase db = getWritableDatabase(); ContentValues values = new ContentValues(); values.put("name",student.getName()); values.put("number",student.getNumber()); values.put("gender",student.getGender()); values.put("score",student.getScore()); return db.insert(TABLE_NAME_STUDENT,null,values); } //根据学号删除信息防止有重名的同学 public int deleteFromDbByNumber(String number){ SQLiteDatabase db=getWritableDatabase(); //返回的是删除的条数 return db.delete(TABLE_NAME_STUDENT,"number like ?",new String[] {number}); } //修改数据 public int updateData(Student student){ SQLiteDatabase db=getWritableDatabase(); ContentValues values = new ContentValues(); values.put("name",student.getName()); values.put("number",student.getNumber()); values.put("gender",student.getGender()); values.put("score",student.getScore()); //依旧是根据学号改 return db.update(TABLE_NAME_STUDENT,values,"number like ?",new String[] {student.getNumber()}); } //查询数据 public List<Student> queryFromByNumber(String number){ SQLiteDatabase db=getWritableDatabase(); List<Student> studentList=new ArrayList<>(); Cursor cursor=db.query(TABLE_NAME_STUDENT,null,"number like ?",new String[] {number},null,null,null); if(cursor!=null){ while (cursor.moveToNext()){ int name1=cursor.getColumnIndex("name"); String name= cursor.getString(name1); int number1=cursor.getColumnIndex("number"); String number2= cursor.getString(number1); int gender1=cursor.getColumnIndex("gender"); String gender= cursor.getString(gender1); int score1=cursor.getColumnIndex("score"); String score= cursor.getString(score1); Student student=new Student(); student.setName(name); student.setNumber(number2); student.setGender(gender); student.setScore(score); studentList.add(student); } cursor.close(); } return studentList; } }