android:SQLite查询与条件之间的问题
我有一个具有如下架构的表:
db.execSQL("CREATE TABLE TBL_REMINDERS (" //
+ "FLD_YEAR INTEGER, " //
+ "FLD_MON INTEGER, " //
+ "FLD_DATE INTEGER, " //
+ "FLD_HOUR INTEGER, " //
+ "FLD_MIN INTEGER, " //
+ "FLD_EVENT TEXT" //
+ ")" //
其中 FLD_MON 字段的范围为 [1,12],FLD_DATE [1,31]、FLD_HOUR [0,23]、FLD_MIN [0,59]
并且针对如下表的 rawQuery 不返回结果集:
public List<Reminder> getRemindersBetween(int y1, int m1, int d1, int h1, int min1, int y2, int m2, int d2, int h2,
int min2) {
String sql = "SELECT FLD_YEAR, FLD_MON, FLD_DATE, FLD_HOUR, FLD_MIN, FLD_EVENT FROM TBL_REMINDERS "//
+ "WHERE (100000000 * FLD_YEAR + 1000000 * FLD_MON + 10000 * FLD_DATE + 100 * FLD_HOUR + FLD_MIN BETWEEN ? AND ?) " //
+ "ORDER BY FLD_YEAR, FLD_MON, FLD_DATE, FLD_HOUR, FLD_MIN, FLD_EVENT ";
SQLiteDatabase db = null;
Cursor cur = null;
try {
db = new CalendarDBOpenHelper(context).getReadableDatabase();
cur = db.rawQuery(sql, new String[] { "" + (100000000 * y1 + 1000000 * m1 + 10000 * d1 + 100 * h1 + min1),//
"" + (100000000 * y2 + 1000000 * m2 + 10000 * d2 + 100 * h2 + min2 - 1) //
});
List<Reminder> list = new ArrayList<Reminder>();
while (cur.moveToNext()) {
int year = cur.getInt(0);
int mon = cur.getInt(1);
int date = cur.getInt(2);
int hour = cur.getInt(3);
int min = cur.getInt(4);
String event = cur.getString(5);
list.add(new Reminder(year, mon, date, hour, min, event));
}
return list;
} finally {
if (null != cur) {
try {
cur.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != db) {
try {
db.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
而另一个 rawQuery 如下所示工作正常:
public List<Reminder> getRemindersOfDate(int y, int m, int d) {
String sql = "SELECT FLD_HOUR, FLD_MIN, FLD_EVENT FROM TBL_REMINDERS "//
+ "WHERE FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
+ "ORDER BY FLD_HOUR, FLD_MIN, FLD_EVENT";
SQLiteDatabase db = null;
Cursor cur = null;
try {
db = new CalendarDBOpenHelper(context).getReadableDatabase();
cur = db.rawQuery(sql, new String[] { "" + y, "" + m, "" + d });
List<Reminder> reminders = new ArrayList<Reminder>();
while (cur.moveToNext()) {
int hour = cur.getInt(0);
int min = cur.getInt(1);
String event = cur.getString(2);
reminders.add(new Reminder(y, m, d, hour, min, event));
}
return reminders;
} finally {
if (null != cur) {
try {
cur.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != db) {
try {
db.close();
} catch (Exception e) {
e.printStackTrace();
}
}
} // finally
}
我猜想是“Between ... and ...”条件造成了麻烦,因为这是两个 SQL 查询之间的唯一区别。但我不确定
编辑:
事情变得有趣了。我现在确信问题是由 where 子句中的表达式引起的。在上面的第二种方法中,如果我修改
+ "WHERE FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
为
+ "WHERE 10 * FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
以及
cur = db.rawQuery(sql, new String[] { "" + (10 * y), "" + m, "" + d });
那么我什么也得不到
I have a table with schema like this:
db.execSQL("CREATE TABLE TBL_REMINDERS (" //
+ "FLD_YEAR INTEGER, " //
+ "FLD_MON INTEGER, " //
+ "FLD_DATE INTEGER, " //
+ "FLD_HOUR INTEGER, " //
+ "FLD_MIN INTEGER, " //
+ "FLD_EVENT TEXT" //
+ ")" //
where the FLD_MON field is in range [1,12], and FLD_DATE [1,31], FLD_HOUR [0,23], FLD_MIN [0,59]
and a rawQuery against the table as below returns no result set:
public List<Reminder> getRemindersBetween(int y1, int m1, int d1, int h1, int min1, int y2, int m2, int d2, int h2,
int min2) {
String sql = "SELECT FLD_YEAR, FLD_MON, FLD_DATE, FLD_HOUR, FLD_MIN, FLD_EVENT FROM TBL_REMINDERS "//
+ "WHERE (100000000 * FLD_YEAR + 1000000 * FLD_MON + 10000 * FLD_DATE + 100 * FLD_HOUR + FLD_MIN BETWEEN ? AND ?) " //
+ "ORDER BY FLD_YEAR, FLD_MON, FLD_DATE, FLD_HOUR, FLD_MIN, FLD_EVENT ";
SQLiteDatabase db = null;
Cursor cur = null;
try {
db = new CalendarDBOpenHelper(context).getReadableDatabase();
cur = db.rawQuery(sql, new String[] { "" + (100000000 * y1 + 1000000 * m1 + 10000 * d1 + 100 * h1 + min1),//
"" + (100000000 * y2 + 1000000 * m2 + 10000 * d2 + 100 * h2 + min2 - 1) //
});
List<Reminder> list = new ArrayList<Reminder>();
while (cur.moveToNext()) {
int year = cur.getInt(0);
int mon = cur.getInt(1);
int date = cur.getInt(2);
int hour = cur.getInt(3);
int min = cur.getInt(4);
String event = cur.getString(5);
list.add(new Reminder(year, mon, date, hour, min, event));
}
return list;
} finally {
if (null != cur) {
try {
cur.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != db) {
try {
db.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
while another rawQuery as below works fine:
public List<Reminder> getRemindersOfDate(int y, int m, int d) {
String sql = "SELECT FLD_HOUR, FLD_MIN, FLD_EVENT FROM TBL_REMINDERS "//
+ "WHERE FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
+ "ORDER BY FLD_HOUR, FLD_MIN, FLD_EVENT";
SQLiteDatabase db = null;
Cursor cur = null;
try {
db = new CalendarDBOpenHelper(context).getReadableDatabase();
cur = db.rawQuery(sql, new String[] { "" + y, "" + m, "" + d });
List<Reminder> reminders = new ArrayList<Reminder>();
while (cur.moveToNext()) {
int hour = cur.getInt(0);
int min = cur.getInt(1);
String event = cur.getString(2);
reminders.add(new Reminder(y, m, d, hour, min, event));
}
return reminders;
} finally {
if (null != cur) {
try {
cur.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != db) {
try {
db.close();
} catch (Exception e) {
e.printStackTrace();
}
}
} // finally
}
I guess it's the `between ... and ...' condition that is making trouble since that's the only difference between the two SQL queries. but I'm not sure
EDIT:
things are getting interesting. I'm sure now that the problem is caused by having an expression in the where clause. In the second method above, if i modify
+ "WHERE FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
to
+ "WHERE 10 * FLD_YEAR=? AND FLD_MON=? AND FLD_DATE=? " //
as well as
cur = db.rawQuery(sql, new String[] { "" + (10 * y), "" + m, "" + d });
then I get nothing
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好吧,首先:它们绝对不一样。
第一个返回特定时间跨度内的匹配条目。
第二个返回月份、年份和日期具有给定值的条目。
编辑
尝试在表达式中使用大括号,因此
(10 * FLD_YEAR)
Okay first of all: They are definitely not the same.
The first returns matching entries in a certain timespan.
The second returns entries where month, year and date have the given values.
Edit
Try to use braces for the expression, so
(10 * FLD_YEAR)