android sqlite数据库饼图

Question

我只是想知道您是否可以帮助我解决我一直遇到的问题。
我创建了一个 SQLite 数据库，我希望根据是否在特定日期服用药物来创建饼图。

用于创建 table

的代码

    // sql query to create table for daily routine
    String sql6 = "CREATE TABLE "
            + TABLE_DAILY_ROUTINE + " ( "
            + COL_DAILY_ROUTINE_DATE + " VARCHAR, "
            + COL_DAILY_ROUTINE_TIME_ID + " INTEGER,"
            + COL_DAILY_ROUTINE_TIME_HOUR + " INTEGER , "
            + COL_DAILY_ROUTINE_TIME_MIN + " INTEGER , "
            + COL_DAILY_ROUTINE_MED_TAKEN + " TEXT ,"
            + COL_DAILY_ROUTINE_MED_QUANTITY + " INTEGER, "
            + COL_DAILY_ROUTINE_MED_ID + " VARCHAR,  "
            + "PRIMARY KEY ( " + COL_DAILY_ROUTINE_DATE + ", " + COL_DAILY_ROUTINE_TIME_ID + "),"
            + "FOREIGN KEY ( " + COL_DAILY_ROUTINE_MED_ID + ") REFERENCES " + TABLE_MEDICATION + "("
            + COL_MEDICATION_ID + ") ON DELETE CASCADE);";

饼图Activity

public class PieChart extends Activity {

SQLiteDatabase ourDatabase;
Database db;
DatabaseHelper dbHelper;
String date;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.pie_chart_layout);
    db = new Database(this);
    db.open();
    dbHelper = new DatabaseHelper(this);
    ourDatabase = dbHelper.getWritableDatabase();


    String sql = "SELECT DAILY_ROUTINE_MED_TAKEN, COUNT(DAILY_ROUTINE_MED_TAKEN) FROM DAILY_ROUTINE\n" +
            "WHERE DAILY_ROUTINE_DATE = ' + date + ' GROUP BY DAILY_ROUTINE_MED_TAKEN " ;
    Calendar calendar = Calendar.getInstance();
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    calendar.add(Calendar.DATE, 1);
    date = sdf.format(calendar.getTime());
    Cursor c = ourDatabase.rawQuery(sql, null);
    int count = c.getCount();
    int[] colors={Color.RED, Color.GREEN};

    double[] values = new double[count];
    String[] categoryNames = new String[count];

    for (int i = 0; i < count; i++) {
        c.moveToNext();
        categoryNames[i] = c.getString(0);
        values[i] = c.getDouble(1);
    }
    // Instantiating CategorySeries to plot Pie Chart
    CategorySeries distributionSeries = new CategorySeries(" Android version distribution as on October 1, 2012");
    for (int i = 0; i < categoryNames.length; i++) {
        // Adding a slice with its values and name to the Pie Chart
        distributionSeries.add(categoryNames[i], values[i]);
    }

    // Instantiating a renderer for the Pie Chart
    DefaultRenderer defaultRenderer = new DefaultRenderer();
    for (int i = 0; i < categoryNames.length; i++) {
        SimpleSeriesRenderer seriesRenderer = new SimpleSeriesRenderer();
        seriesRenderer.setColor(colors[i]);
        seriesRenderer.setDisplayChartValues(true);
        defaultRenderer.addSeriesRenderer(seriesRenderer);
    }

    defaultRenderer.setChartTitle("Patient Daily Adherance to Medication");
    defaultRenderer.setChartTitleTextSize(60);
    defaultRenderer.setZoomButtonsVisible(false);
    defaultRenderer.setLegendTextSize(70);
    defaultRenderer.setLabelsTextSize(80);

    Intent intent = ChartFactory.getPieChartIntent(getApplicationContext(), distributionSeries, defaultRenderer, "AChartEnginePieChartDemo");

    // Start Activity
    startActivity(intent);

    c.close();
    ourDatabase.close();
}
}

数据库是正确的，当我硬编码一个日期来替换字符串日期时，我得到一个饼图显示。
字符串日期是前面的一天，因为这是日期在数据库中的时间。这不是问题。

没有出现错误。
显示了标题，但没有饼图，请问您能帮我解决一下问题吗？
我确定它与初始的 for 循环有关，但我无法确定。

Answer 1

我认为您需要移动一些代码行，并连接 date 变量的值。

现在，您正在尝试查询列明确等于 ' + date + ' 的字符串的位置。

// What is 'date' here? null, most likely... 
String sql = "SELECT DAILY_ROUTINE_MED_TAKEN, COUNT(DAILY_ROUTINE_MED_TAKEN) FROM DAILY_ROUTINE\n" +
        "WHERE DAILY_ROUTINE_DATE = ' + date + ' GROUP BY DAILY_ROUTINE_MED_TAKEN " ;

// Here's where you do get the value of the date string 
Calendar calendar = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
calendar.add(Calendar.DATE, 1);
date = sdf.format(calendar.getTime()); 

// move the sql down here

我还建议尝试使用 SqliteDatabase class 的 query 方法而不是 execSQL 或 rawQuery 但这是个人偏好

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