我在这个查询中得到 0 个结果。我究竟做错了什么？ （安卓）

Question

我在 Android 上使用 SQLite。这是我的三张表：

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，我在进行以下查询后得到0个结果：

  Cursor cur = databaseHelper.getDebtsByConcept(0);

执行查询的地方如下：

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

数据库中不会有任何conecptID 值为0 的条目，同样的原因是您已将concept table 中的conceptID 声明为Integer Auto Increment，因此当您插入第一条记录时，值将是conceptId 值将是1，

您可以尝试在查询中传递 1，然后只是检查一下，尝试使用 select * from .... 从数据库中获取所有记录