android - 我在此查询中得到 0 个结果。我究竟做错了什么？ (安卓)

Question

我在 Android 上使用 SQLite。这是我的三个表:

String query = "create table " + TABLE_PERSON + " (" +
            PERSON_COL_ID + "  integer PRIMARY KEY AUTOINCREMENT, " +
            PERSON_COL_NAME + " text, " +
            PERSON_COL_SEX + " text CHECK (" + PERSON_COL_SEX + " IN ('M', 'F'))" +
            ");";
db.execSQL(query);

query = "create table " + TABLE_CONCEPT + " (" +
            CONCEPT_COL_ID + " integer PRIMARY KEY AUTOINCREMENT, " +
            CONCEPT_COL_NAME + " text, " +
            CONCEPT_COL_DATE + " text " +
            ");";
db.execSQL(query);

query = "create table " + TABLE_DEBT + " (" +
            DEBT_COL_ID + " integer PRIMARY KEY AUTOINCREMENT, " +
            DEBT_COL_CONCEPT + " integer REFERENCES " + TABLE_CONCEPT + ", " +
            DEBT_COL_CREDITOR + " integer REFERENCES " + TABLE_PERSON + ", " +
            DEBT_COL_DEBTOR + " integer REFERENCES " + TABLE_PERSON + ", " +
            DEBT_COL_ORIGAMT + " integer, " +
            DEBT_COL_PAIDSOFAR + " integer, " +
            DEBT_COL_DATEREPAID + " text" +
            ");";
db.execSQL(query);

插入 3 个人、2 个概念和 1 个债务后，进行以下查询后我得到 0 个结果:

  Cursor cur = databaseHelper.getDebtsByConcept(0);

执行的查询如下:

public Cursor getDebtsByConcept(int conceptID) {
     String query = "select con.name, per1.name, per2.name, deb.origamt, deb.paidsofar, deb.daterepaid" +
            " from " +
            TABLE_PERSON + " per1, " + TABLE_PERSON + " per2, " +  TABLE_CONCEPT + " con, " + TABLE_DEBT + " deb" +
            " where deb.concept = " + conceptID +
            " and con.id = deb.concept " +
            " and per1.id = deb.creditorID" +
            " and per2.id = deb.debtorID;";

     Cursor res = db.rawQuery(query, null);
     return res;
}

Answer 1

conecptID 值为 0 的数据库中不会有任何条目，同样的原因是您已在 concept table 中声明了 conceptID > 作为 Integer Auto Increment 所以当你插入第一个记录值时 conceptId 值将是 1,

您能否尝试在您的查询中传递 1，并且只是为了检查最初尝试使用 select * from ... 从数据库中获取所有记录。