如何在数据库SQLiteOpenHelper中保存小时/分钟？
时钟和分钟格式？例如：12:40或00:00。
答案 0 :(得分：0)
只需将其保存为String并将其格式化，就像每次使用时一样。
Sqlite没有DATETIME类型。
答案 1 :(得分：0)
您可以通过多种方式保存此类数据，如文本/字符串，整数0-1440，两个整数（一个用于小时，一个用于分钟），长度为十进制。
选择可能取决于后续使用，如果它只是显示然后文本/字符串可能是合适的。如果要执行计算，则text / string可能会导致复杂的过程（请参阅下面示例中的getElapsedTimeForAllTimesAsInt）。
要考虑的一个因素是如何/如果SQLite日期时间函数会有什么好处，如果是这样，那么以它识别的格式之一保存是明智的（HH：MM（24小时制）就是这样的格式） 。必读为SQL As Understood By SQLite - Date And Time Functions。
下面是一个可以节省时间（以及也许不怎么样）的工作示例： -
insertTime getAllTimesAsCursor将所有行检索为Cursor。getAllTimesAsStringArray将所有行检索为String [] （请注意，它使用getAllTimesAsCursor） getElapsedTimeOfAllTimesAsInt，返回最早和最晚时间之间的分钟数。这是为了演示如何转换/提供非sqlite日期格式可能会有点复杂（注意它有缺陷而且不打算使用）： -
public class SOD49707387DBHelper extends SQLiteOpenHelper {
public static final String DBNAME = "mydatabase";
public static final int DBVERSION = 1;
public static final String TBNAME_TIME = "mytimesave";
public static final String TIME_COL_TIME = "_time";
SQLiteDatabase mDB;
public SOD49707387DBHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
mDB = this.getReadableDatabase();
}
@Override
public void onCreate(SQLiteDatabase db) {
String crtsql = "CREATE TABLE IF NOT EXISTS " + TBNAME_TIME + "(" +
TIME_COL_TIME + " TEXT" +
")";
db.execSQL(crtsql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// Not assumes that time is valid
public boolean insertTime(String time) {
ContentValues cv = new ContentValues();
cv.put(TIME_COL_TIME,time);
return (mDB.insert(TBNAME_TIME,null,cv) > 0);
}
public Cursor getAllTimesAsCursor() {
return mDB.query(TBNAME_TIME,
null,
null,
null,
null,
null,
null);
}
public String[] getAllTimesAsStringArray() {
Cursor csr =getAllTimesAsCursor();
String[] rv = new String[csr.getCount()];
while (csr.moveToNext()) {
rv[csr.getPosition()] = csr.getString(csr.getColumnIndex(TIME_COL_TIME));
}
csr.close();
return rv;
}
/*
NOTE!! equates to query
SELECT
max((substr(_time,1,2) * 60) + substr(_time,4,2))
-
min((substr(_time,1,2) * 60) + substr(_time,42))
AS elapsedminutes
FROM mytimesave;
NOTE!!! inherently unreliable as assumes all rows are valid
*/
public int getElapsedTimeOfAllTimesAsInt() {
int rv = 0;
String result_column =
"" +
"max((substr(" +
TIME_COL_TIME +
",1,2) * 60) + substr(" +
TIME_COL_TIME + ",4,2))" +
" - " +
" min((substr(" +
TIME_COL_TIME +
",1,2) * 60) + substr(" +
TIME_COL_TIME +
",4,2))" +
" AS " + TIME_COL_TIME //??? hijack _time column
;
Cursor csr = mDB.query(
TBNAME_TIME,
new String[]{result_column},
null,
null,
null,
null,
null);
if (csr.moveToFirst()) {
rv = csr.getInt(csr.getColumnIndex(TIME_COL_TIME));
}
csr.close();
return rv;
}
}
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SO49707387(); // call method for this answer
}
private void SO49707387() {
// Instantiate DBHelper instance
SOD49707387DBHelper dbhlpr = new SOD49707387DBHelper(this);
// Insert some data (2 rows each time App is run)
dbhlpr.insertTime("12:00");
dbhlpr.insertTime("08:00 AM");
// Get database information (*1)
CommonSQLiteUtilities.logDatabaseInfo(dbhlpr.getWritableDatabase());
// Get all times as a Cursor
Cursor csr = dbhlpr.getAllTimesAsCursor();
// traverse the Cursor writing data to the log
while (csr.moveToNext()) {
Log.d("TIME_VIA_CURSOR",
csr.getString(
csr.getColumnIndex(
SOD49707387DBHelper.TIME_COL_TIME)
)
);
}
csr.close(); //<<< Should always close cursor when done with them
// get all times as a String array
String[] times = dbhlpr.getAllTimesAsStringArray();
// traverse the array writing data to the log
for (String s: times) {
Log.d("TIME_VIA_ARRAY",s);
}
// Calculate and print the elapsed time
// (largest time - smallest time)
// i.e. 12:00 - 08:00 = 240 minutes = 4 hours
Log.d("ELAPSED",
"The elapsed time in minutes is " +
String.valueOf(dbhlpr.getElapsedTimeOfAllTimesAsInt())
);
}
}
CommonSQLiteUtilities 类的来源here。04-08 03:33:00.055 1945-1945/? D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/soanswers.soanswers/databases/mydatabase Database Version = 1 Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT) Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0 Table Name = mytimesave Created Using = CREATE TABLE mytimesave(_time TEXT) Table = mytimesave ColumnName = _time ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0 04-08 03:33:00.059 1945-1945/? D/TIME_VIA_CURSOR: 12:00 08:00 AM 04-08 03:33:00.059 1945-1945/? D/TIME_VIA_ARRAY: 12:00 08:00 AM 04-08 03:33:00.059 1945-1945/? D/ELAPSED: The elapsed time in minutes is 240