Java的Andr​​oid的 - 问题与SQLite数据库拉着一个变量 [英] Java Android - Issue with pulling a variable from SQLite database

问题描述

所以，我想从我的SQLite数据库拉称为totalWater一个整数，但是当我试图把它然后将其添加到另一个号码，这表明，我从数据库中抽取的数量是零。我不知道如果我揪错了，或者如果我连其存储到数据库中是错误的。

So I am trying to pull an integer called "totalWater" from my SQLite database but when I try to pull it and then add it to another number, it shows that the number that I pulled from the database is zero. I'm not sure if I am pulling wrong, or if I am even storing the value into the database wrong.

这是我的code处理拉，并与数据库推：

here is my code dealing with pulling and pushing with the database:

//pull data
data = new Database(SetupTimerPC1.this);
data.open();
totalWater = data.getWaterAmt();            
data.close();

//add new data to old
totalWater+=waterAmt;

//push data
data.open();
data.waterAmountEntry(totalWater);
data.close();

这里在数据库中的功能处理waterAmt：

here is the function in the database dealing with waterAmt:

public int getWaterAmt() 
{
    int waterAmount = 0;

    String[] columns = new String[] {KEY_ROWID, KEY_ROCK, KEY_METEORROCK, KEY_WATER,
    KEY_POPULATION, KEY_SHOVEL, KEY_BUCKET, KEY_PICKAXE, KEY_SHOVELEXP,
    KEY_BUCKETEXP, KEY_PICKAXEEXP};

    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);

    if (c != null && c.getCount() > 0)
    {
        c.moveToFirst();
        iWaterAmount = c.getColumnIndex(KEY_WATER);
        waterAmount = c.getInt(iWaterAmount);
        return waterAmount;
    }//end if        return 0;
}//end getWaterAmt function

和这里是我的waterAmountEntry功能进入的水量到数据库：

and here is my waterAmountEntry function to enter the amount of water into the database:

public long waterAmountEntry(int waterAmt)
{
    ContentValues cv = new ContentValues();
    cv.put(KEY_WATER, waterAmt);
    return ourDatabase.insert(DATABASE_TABLE, null, cv);
}//end waterAmountEntry function

任何帮助将AP preciated。谢谢你。

Any help will be appreciated. Thanks.

推荐答案

添加一个for循环，在c.moveToFirst（）通过c.movetonext开始！c.isafterlast（）和增量的条件（）里面我if语句检查是否光标在空让我来解决这个问题：

Adding a for loop that started at c.moveToFirst() with a condition of !c.isafterlast() and increment by c.movetonext() inside of my if statement checking if the cursor was null allowed me to fix the issue:

for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
{
    iWaterAmount = c.getColumnIndex(KEY_WATER);
    waterAmount = c.getInt(iWaterAmount);
}//end for
c.close();

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