使用内容值更新方法

问题描述

帮手

public boolean mMessagesSent(String ID,int Data) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(KEY_ID, ID);
    contentValues.put(KEY_MESSAGES_SENT, Data);
    db.update(TABLE_USER_DATA, contentValues, null, null);
    return true;
}

活动

mainData.mTotalMessages("MyData", +1);
        mainData.mTotalMessagesSent("MyData",+1);
        mainData.mMessages(MessageRecieverId,+1);
        mainData.mMessagesSent(MessageRecieverId,+1);

这是更新数据的正确方法吗...我想将数据的 int 值增加 1，所以我已经输入了 +1 但当我检索数据时该值仍然为空

Is this the correct method to update data... I want to increase the int value of data by 1 so i have put +1 but still the value is empty when i retrieve data

遵循第一个答案后的代码

public boolean mMessagesSent(String ID,int Data) {
    MainData mainData = new MainData(getApplicationContext());
    SQLiteDatabase db = mainData.getWritableDatabase();
    String newId = ID;
    int newData = Data;
    MainData helper = new MainData(this); //Change the name to your Helper Class name
    Cursor data = helper.getData();
    while (data.moveToNext()) {
        newId = data.getString(data.getColumnIndex("Data"));
        newData = data.getInt(data.getColumnIndex("TotalMessagesSent"));
    }
    ContentValues contentValues = new ContentValues();
    contentValues.put(KEY_DATA, newId);
    contentValues.put(KEY_MESSAGES_SENT, (newData + 1)); //Change the value of newData(which is actually your old value) by incrementing
    db.update(TABLE_USER_DATA, contentValues, null, null);
    return true;
}

获取

final MainData myDBHlpr = new MainData(getActivity());

    Cursor csr = myDBHlpr.getAllQuestions(getActivity());
    while (csr.moveToNext()) {

        mTotalMessagesSent.setText(csr.getString(1));
        mTotalMessagesRecieved.setText(csr.getString(csr.getColumnIndex("TotalMessagesRecieved")));
        mTotalMessages.setText(csr.getString(csr.getColumnIndex("TotalMessages")));

    }

        csr.close();

推荐答案

如果您打算每次调用函数mMessagesSent()

If you meant to increase the existing value of data by once each time you call the function mMessagesSent()

可以考虑先从数据库中取值(如果存在)，并递增该值.在Helper中创建一个函数如下图

You can consider to first take the value from the database if it exists, and increment the value. Create a function in Helper as shown below

public Cursor getData(){

    SQLiteDatabase db = this.getWritableDatabase();
    String query = "SELECT * FROM " + TABLE_NAME;

    return db.rawQuery(query, null);
}

这将返回一个光标到数据库，以读取数据库中的值.函数mMessagesSent不要放在Helper类中，放在Activity中.现在在您的 mMessagesSent 函数中，调用上面的函数 getData()，如图所示

This will return a Cursor to the Database, to read the values in the database. Do not put the function mMessagesSent in Helper class, put it in the Activity. Now in your mMessagesSent function, call the above function getData() as shown

public void mMessagesSent() {
SQLiteDatabase db = this.getWritableDatabase();
String newId = "default value whatever you have specified";//These two lines may be removed and put outside. If you already have it, then
int newData = 0;                                           //not required to declare here at all, just replace with those variable names
HelperClassName helper = new HelperClassName(this); //Change the name to your Helper Class name
Cursor data = helper.getData();
while(data.moveToNext()){
    newId = data.getString(0);
    newData = data.getInt(1);
}
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_ID, ID);
contentValues.put(KEY_MESSAGES_SENT, (newData+1)); //Change the value of newData(which is actually your old value) by incrementing
long returnVariable = db.update(TABLE_USER_DATA, contentValues, null, null);
if(returnVariable == -1){
    //-1 means there was an error updating the values
}
else{
//the return value if successful will be number of rows affected by the update
}
}

希望你能得到答案.

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