“如何在 android studio 中使用游标从多个表中检索数据”

Question

我尝试使用游标从两个表中检索数据，但我只从一个表中获取数据。 请帮忙。

这是完整的代码。

//创建表

//表T24

db.execSQL("CREATE TABLE IF NOT EXISTS T24 (ID NUMBER PRIMARY KEY,STARTING VARCHAR,DESTINATION VARCHAR" +
                        ",PLACES VARCHAR,PLACESFARE NUMBER(9,3),HOTELS VARCHAR,HOTELSFARE NUMBER(9,3),TRANSPORT VARCHAR," +
                        "TRANSPORTFARE VARCHAR,DAYS INTEGER,TOTALFARE NUMBER(9,3))");

//表P21

 db.execSQL("CREATE TABLE IF NOT EXISTS P21"+"(NAME VARCHAR PRIMARY KEY,NO NUMBER," +
                    "ADDRESS VARCHAR,DAYS NUMBER,DATE NUMBER,MONTH NUMBER)");

//从数据库中检索数据。

 db = openOrCreateDatabase("tour", Context.MODE_PRIVATE, null);
         String query1 = "select *from T24 where " +
               "STARTING='" + s3 + "' and DESTINATION='" + s4 + "'";
        Cursor c = db.rawQuery(query1, null);
        if (c.moveToFirst() == true) {
            t1 = c.getString(3);
            t2 = c.getString(4);
            t3 = c.getString(5);
            t4 = c.getString(6);
            t5 = c.getString(7);
            t6 = c.getString(8);
            t7 = c.getString(9);
            t8 = c.getString(10);
        }
        c.close();
        db.close();
        ptv.setText(t1);
        pf.setText(t2);
        hotels.setText(t3);
        hf.setText(t4);
        td.setText(t5);
        tf.setText(t6);
        fare.setText(t8);
        try {
            db2 = openOrCreateDatabase("tour", Context.MODE_PRIVATE, null);
            String query2 = "select *from P21 where" +
                    "NAME='" + e1 + "'";
            Cursor c1 = db2.rawQuery(query2, null);
            if (c1.moveToFirst() == true) {
                t9 = c1.getString(0);
                t10 = c1.getString(1);
                t11 = Integer.parseInt(c1.getString(3));
                t12 = Integer.parseInt(c1.getString(4));
                t13 = Integer.parseInt(c1.getString(5));
            }
            c1.close();
            db2.close();
            Toast.makeText(getApplicationContext(), "done3", Toast.LENGTH_LONG).show();
            name.setText(t9);
            no.setText(t10);
            sdate1.setText(t12);
            sdate2.setText(t13);

我能够从表“T24”中检索日期，但无法从表“P21”中检索数据。

请帮忙。

Answer 1

我认为你在 P21 的 sqlite 句子中的“where”之后留了空格：

String query2 = "select *from P21 where" +
                "NAME='" + e1 + "'";

你需要这样写：

String query2 = "select * from P21 where " +
                "NAME='" + e1 + "'";