那么，在 SQLite 中进行时间查询的方法是什么？
我需要查询某个时间段内的数据。例如，从 07:00:00 到 10:00:00
根据您的数据，您不会发现任何行，因为 03:43:16 等不在范围内。否则您的查询工作正常。
W/System.err: java.text.ParseException: Unparseable date: "07:00:00" 的问题不在查询中，而是在其他地方。您似乎正在尝试从某个时间开始日期，而解析器拒绝了它。
- （例如，哪个月是 00，一个月中的哪一天是 00）
当您尝试将时间解析为日期时，这会在其他地方发生。
演示
考虑以下哪个
a) 表明您的查询有效
b) 演示改进的查询
d) 演示获取您遇到的错误的示例
@SuppressLint("Range")
public class MainActivity extends AppCompatActivity {
static final String LOG_TAG = "LOGDBINFO";
DBHelper dbHelper;
Cursor c;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbQuery("01:00:00","19:00:00",1);
while(c.moveToNext()) {
Log.d(LOG_TAG+"RUN1",
"Number is " + c.getString(c.getColumnIndex("number")) +
" Date is " + c.getString(c.getColumnIndex("date")) +
" Time is " + c.getString(c.getColumnIndex("time"))
);
}
improvedQuery("01:00:00","19:00:00",1);
while(c.moveToNext()) {
Log.d(LOG_TAG+"RUN2",
"Number is " + c.getString(c.getColumnIndex("number")) +
" Date is " + c.getString(c.getColumnIndex("date")) +
" Time is " + c.getString(c.getColumnIndex("time"))
);
}
/* reposition the cursor before the first row */
c.moveToPosition(-1);
while (c.moveToNext()) {
try {
Date ok = sdf.parse(c.getString(c.getColumnIndex("date")) + " " + c.getString(c.getColumnIndex("time")));
//Date test = sdf.parse(c.getString(c.getColumnIndex("date"))); // Fails as no time
Date test2 = sdf.parse(c.getString(c.getColumnIndex("time")));
} catch (ParseException e) {
e.printStackTrace();
}
}
}
public void dbQuery(String startTime, String stopTime, Integer number) {
dbHelper = new DBHelper(this);
String selection = null;
SQLiteDatabase db = dbHelper.getWritableDatabase();
Log.d(LOG_TAG, "--- Connected myDB: ---");
selection = "number = " + "\'" + number + "\'"
+ " and " + "time between " + "\'" + startTime + "\'"
+ " and " + "\'" + stopTime + "\'"
;
c = db.query("MyDB", null, selection, null, null, null,null);
}
/* This Binds the values passed which reduces the chance for SQLite Injection and
also encloses the passed values in single quotes as required
*/
public void improvedQuery(String startTime, String stopTime, Integer number) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
c = db.query(
"MyDB",null,
"number =? AND time between ? AND ?",
new String[]{String.valueOf(number),startTime,stopTime},
null,null,null);
}
}
在查询日志后运行循环时：-
D/LOGDBINFO: --- Connected myDB: ---
D/LOGDBINFORUN1: Number is 1 Date is 2021-12-15 Time is 03:43:16
D/LOGDBINFORUN1: Number is 1 Date is 2021-12-15 Time is 03:54:35
D/LOGDBINFORUN1: Number is 1 Date is 2021-12-15 Time is 03:56:32
改进后的查询日志：-
D/LOGDBINFORUN2: Number is 1 Date is 2021-12-15 Time is 03:43:16
D/LOGDBINFORUN2: Number is 1 Date is 2021-12-15 Time is 03:54:35
D/LOGDBINFORUN2: Number is 1 Date is 2021-12-15 Time is 03:56:32
但是在没有遇到线路问题后：-
Date ok = sdf.parse(c.getString(c.getColumnIndex("date")) + " " + c.getString(c.getColumnIndex("time")));
在该行中捕获一个异常：-
Date test2 = sdf.parse(c.getString(c.getColumnIndex("time")));
这是您遇到的异常，即日志显示：-
W/System.err: java.text.ParseException: Unparseable date: "03:43:16"
W/System.err: at java.text.DateFormat.parse(DateFormat.java:362)
W/System.err: at a.a.so70357434.MainActivity.onCreate(MainActivity.java:50)
- 请注意，最后一条消息详细说明了确切的行，在 Android Studio 中，它还有一个链接，如果单击该链接会将您带到有问题的行。
- 因此，在询问存在异常的问题时，为什么要包含堆栈/日志。