First create a database table, and then perform the delete update operation in the main activity
public< /span> class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Mysqlite mysqlite = new Mysqlite(this);
SQLiteDatabase sqLiteDatabase = mysqlite.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("id", 0);
contentValues.put("name", "张三");
sqLiteDatabase.insert("student", null, contentValues);
System.out.println("Insert data");
Cursor cursor = sqLiteDatabase.query("student", new String[]{"id", "name"}, " id=?", new String[]{"0"}, null,
null, null);
while (cursor.moveToNext()) {
String id = cursor.getString(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
System.out.println(id + "" + name);
}
ContentValues contentValues1 = new ContentValues();
contentValues1.put("name", "李四");
sqLiteDatabase.update("student", contentValues1, "id=?", new String[]{"0"}) ;//? is a placeholder, followed by String
// Element 0 of the array fills the placeholder in front?, That is, id=0, whereClause (where clause) is only a restriction condition
System.out.println("Update data");
sqLiteDatabase.delete("student", "id=?", new String[]{"0"});
System.out.println("Delete data");
deleteDatabase("student");
System.out.println("Delete database");
sqLiteDatabase.close();
}
}
The above is the main activity
public class Mysqlite extends SQLiteOpenHelper {
SQLiteDatabase readableDatabase;
public Mysqlite(Context context) {
super(context, "student", null, 2);
readableDatabase = getWritableDatabase();//No permissions are required to create a database , But this line of code must be written
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table student (id integer,name varchar)");
System.out.println("Create");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
The above is to create a database. //I’m going to talk about the important things three times
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Mysqlite mysqlite = new Mysqlite(this);
SQLiteDatabase sqLiteDatabase = mysqlite.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("id", 0);
contentValues.put("name", "张三");
sqLiteDatabase.insert("student", null, contentValues);
System.out.println("Insert data");
Cursor cursor = sqLiteDatabase.query("student", new String[]{"id", "name"}, " id=?", new String[]{"0"}, null,
null, null);
while (cursor.moveToNext()) {
String id = cursor.getString(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
System.out.println(id + "" + name);
}
ContentValues contentValues1 = new ContentValues();
contentValues1.put("name", "李四");
sqLiteDatabase.update("student", contentValues1, "id=?", new String[]{"0"}) ;//? is a placeholder, followed by String
// Element 0 of the array fills the placeholder in front?, That is, id=0, whereClause (where clause) is only a restriction condition
System.out.println("Update data");
sqLiteDatabase.delete("student", "id=?", new String[]{"0"});
System.out.println("Delete data");
deleteDatabase("student");
System.out.println("Delete database");
sqLiteDatabase.close();
}
}
public class Mysqlite extends SQLiteOpenHelper {
SQLiteDatabase readableDatabase;
public Mysqlite(Context context) {
super(context, "student", null, 2);
readableDatabase = getWritableDatabase();//No permissions are required to create a database , But this line of code must be written
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table student (id integer,name varchar)");
System.out.println("Create");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}