SQlite创建一个带有时间戳列的数据库，并在其中添加一个值 [英] SQlite creating a database with a timestamp column and adding a value in

问题描述

我正在尝试创建一个名为rawData的数据库。数据库将具有一列ID，一个外部用户ID（另一个表中的_id），数据以及最后一个时间戳。

I am trying to create a database that called rawData. The db will hava a column for the id, a foreign user id (_id from another table), data and finally a timestamp.

我的问题是如何创建一个SQlite中的时间戳并将其存储在db中，列也应该是什么类型的文本？数据库需要能够每秒存储150个浮点值并为这150个条目中的每一个添加时间戳。另外，由于SQlite没有浮点类型，我应该使用real作为列类型吗？

My question is how can I create a timestamp in SQlite and store it in the db also what type should the column be, text? the database needs to be able to store 150 float values a second and time stamp each of those 150 entries. Additionally since SQlite doesn't have a float type should i use real as the column type?

public class RawDatabase{
public static final String TABLE_RAW_DATA = "rawData";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_FOREIGN_USER_ID = "foreignUserId";
public static final String COLUMN_DATA = "data";
public static final String COLUMN_TIME_STAMP = "timeStamp";

// Database creation sql statement
private static final String DATABASE_CREATE = "create table "
    + TABLE_RAW_DATA + "(" + COLUMN_ID
    + " integer primary key autoincrement, " + COLUMN_FOREIGN_USER_ID
    + " integer, " + COLUMN_DATA 
    + " real, " + COLUMN_TIME_STAMP
    + " text not null);";
}

推荐答案

文档说：

SQLite没有保留用于存储日期和/或时间的存储类。相反，SQLite内置的日期和时间函数能够将日期和时间存储为TEXT，REAL或INTEGER。值：

SQLite does not have a storage class set aside for storing dates and/or times. Instead, the built-in Date And Time Functions of SQLite are capable of storing dates and times as TEXT, REAL, or INTEGER values:

• TEXT 作为ISO8601字符串（ YYYY-MM-DD HH：MM：SS.SSS ）。


• REAL 作为儒略日数，即自公元前4714年11月24日格林威治中午以来的天数


• INTEGER 作为Unix时间，是自1970-01-01 00:00:00 UTC以来的秒数。

• TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").
• REAL as Julian day numbers, the number of days since noon in Greenwich on November 24, 4714 B.C. according to the proleptic Gregorian calendar.
• INTEGER as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.

应用程序可以选择以任何一种格式存储日期和时间，并使用内置的日期和时间功能在各种格式之间自由转换

Applications can chose to store dates and times in any of these formats and freely convert between formats using the built-in date and time functions.

如果只需要秒精度，请使用Unix Time格式的整数。
否则，请使用小数秒的浮点数。

If you need only seconds precision, use integers in Unix Time format. Otherwise, use floating-pointer numbers for fractional seconds.

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