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;
}
}</student></student>
Original: https://blog.csdn.net/qq_51367068/article/details/124749277
Author: 阿喵酱ovo
Title: Android Studio创建sqlite数据库及SQL语句的执行
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