Question

我无法在现有数据库中添加2列。我阅读了网络上的任何主题，但我无法解决我的问题。我可以对我的问题有一个完整的个性化答案吗？我自然不想失去现有记录，只是改变它！我想添加2列（电话（整数），automex（文本））到以这种方式创建的数据库..

package com.ozzem.mybirthdaylite;



import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class dbMyBirthday {

    SQLiteDatabase db;

    private Context mContext;

    private DbHelper mDbHelper;

     private static final String DB_NAME="dbmyBirthday";
     private static final int DB_VERSION=1;

     //costruttore crea anche il DbHelper
     public dbMyBirthday(Context ctx){
         mContext=ctx;
         mDbHelper=new DbHelper(ctx, DB_NAME, null, DB_VERSION);       
 }


     public void open(){  //il database su cui agiamo è leggibile/scrivibile
         db=mDbHelper.getWritableDatabase();

 }

 public void close(){ //chiudiamo il database su cui agiamo
         db.close();
 }



 public void deletePerson(int idDel){ //metodo per inserire i dati

     String where = "id = " + idDel;
     db.delete(Person.PERSON_TABLE, where,null);
//     Log.d("db_call", "Record of id["+idDel+"] deleted");

}


 public void insertPerson(long l,String name,String birthday){ //metodo per inserire i dati
         ContentValues cv=new ContentValues();
         cv.put(Person.UID, l);
         cv.put(Person.NAME, name);
         cv.put(Person.BIRTHDAY, birthday);

         db.insert(Person.PERSON_TABLE, null, cv);
//         Log.d("db_call", "Record of uid["+uid+"] insered");

 }

 public boolean exist(long uid){
     boolean ex = false;

     Cursor c= db.rawQuery("SELECT COUNT(*) FROM " + Person.PERSON_TABLE + " WHERE uid = "+ "'" + uid + "'", null);
        c.moveToFirst();
      int jcount = c.getInt(0);

      if (jcount >0){
        ex=true;            
    }
     return ex;
 }



 public void updatePersonFromId(int id,String name,String birthday){

     ContentValues cv=new ContentValues();
//   cv.put(Person.UID, id);
     cv.put(Person.NAME, name);
     cv.put(Person.BIRTHDAY, birthday);

     String where = "id = " + "'"+id+"'";
     db.update(Person.PERSON_TABLE, cv, where, null);
//     Log.d("db_call", "Record of id["+id+"] updated");

 }

 public void updatePersonFromUid(long l,String name,String birthday){

     ContentValues cv=new ContentValues();
     cv.put(Person.UID, l);
     cv.put(Person.NAME, name);
     cv.put(Person.BIRTHDAY, birthday);

     String where = "uid = " + "'"+l+"'";
     db.update(Person.PERSON_TABLE, cv, where, null);
//     Log.d("db_call", "Record of uid["+uid+"] updated");

 }

 public Cursor fetchAllBirthday(){ //metodo per fare la query di tutti i dati
//   Log.d("db_call", "Fetching all birthdays");    
     return db.query(Person.PERSON_TABLE, null,null,null,null,null,null);               
 }

 public static class Person {  // i metadati della tabella, accessibili ovunque

        static final String PERSON_TABLE = "person";
         static final String ID = "id";
         static final String UID = "uid";
         static final String NAME = "name";
         public static final String BIRTHDAY = "birthday";

 }

 private static final String PERSON_TABLE_CREATE = "CREATE TABLE IF NOT EXISTS "  //codice sql di creazione della tabella

                + Person.PERSON_TABLE + " (" 
                 + Person.ID + " integer primary key autoincrement, "
                 + Person.NAME + " text not null, "
                 + Person.UID + " integer not null, "
                 + Person.BIRTHDAY + " text not null );";



     private class DbHelper extends SQLiteOpenHelper { //classe che ci aiuta nella creazione del db

         public DbHelper(Context context, String name, CursorFactory factory,int version) {
                 super(context, name, factory, version);
         }

    @Override
    public void onCreate(SQLiteDatabase _db) {
        // TODO Auto-generated method stub

         _db.execSQL(PERSON_TABLE_CREATE);


    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

}
}

Answer 1

将 DB_Version 增加到 2 ，然后在您的 OnUpgrade 覆盖OpenHelper中运行升级代码

例如：

    if (oldVersion==1 && newVersion==2) {
      db.execSQL("ALTER TABLE " + TableName + " ADD COLUMN " + ColumnName1);
      db.execSQL("ALTER TABLE " + TableName + " ADD COLUMN " + ColumnName2);
    }

同时修改您的初始代码，以便为那些没有要升级的版本1数据库的人创建新字段。即那些首先创建第2版数据库的人。

Answer 2

@ozzem以下是您需要在应用程序Start Class上执行的一些步骤。

步骤1.检查数据库中是否已存在2列？见这里SO链接是here

步骤2.在确认运行SQL查询后，确保数据库中没有2列要添加

ALTER TABLE PERSON_TABLE ADD phone INTEGER DEFAULT 0
ALTER TABLE PERSON_TABLE ADD automex TEXT

当您在表格中添加时，您也可以在此列中提供默认值。

将2列添加到sqlite db Android

2 个答案: