问题描述
我的问题是我需要基于“总线时间”字段显示数据库中的所有数据,并与当前时间进行比较,即如果当前时间为6:30 PM,则它应该显示所有“总线时间”字段大于或等于当前时间(6:30)的值。
我已经在android studio的DatabaseHandler.java中编写了一个SQL查询,但是查询中出现错误,请您帮忙解决它。
查询的代码是
public List<Contact> getBus(String t)
{
List<Contact> contactList = new ArrayList<Contact>();
String query = "SELECT * FROM contacts WHERE CAST( bus_time AS TIME ) >= CAST(" + t +" AS TIME )";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query,null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Contact contact = new Contact();
contact.setID(Integer.parseInt(cursor.getString(0)));
contact.setName(cursor.getString(1));
contact.setPhoneNumber(cursor.getString(2));
// Adding contact to list
contactList.add(contact);
} while (cursor.moveToNext());
}
// return contact list
return contactList;
}
我遇到的错误是
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.database,PID: 4539
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.database/com.example.database.MainActivity}: android.database.sqlite.SQLiteException: near ":27": syntax error (code 1):,while compiling: SELECT * FROM contacts WHERE CAST( bus_time AS TIME ) >= CAST(18:27 AS TIME )
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
解决方法
在SQLite中,没有数据类型TIME
,任何日期和/或时间值都应视为TEXT
。
使用函数STRFTIME()
以HH:MM
格式获取当前时间:
SELECT *
FROM contacts
WHERE SUBSTR('0' || bus_time,-5) >= STRFTIME('%H:%M','now','localtime')
如果您将时间保存在bus_time
列中,格式为HH:MM
(小时为2位数字),则不需要使用SUBSTR()
左边的{ {1}}(如果小时只有1位数字,并且代码为:
0