问题描述
我正在尝试创建一个名为 rawData 的数据库.db 将有一个用于 id 的列、一个外部用户 id(来自另一个表的 _id)、数据，最后是一个时间戳.
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.
我的问题是如何在 SQlite 中创建时间戳并将其存储在数据库中，该列应该是什么类型，文本?数据库需要能够每秒存储 150 个浮点值并为这 150 个条目中的每一个提供时间戳.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 没有专门用于存储日期和/或时间的存储类.相反，SQLite 的内置 日期和时间函数 能够将日期和时间存储为 TEXT、REAL 或 INTEGER价值观:
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 Julian day numbers，自公元前 4714 年 11 月 24 日格林威治中午以来的天数.根据预测的公历.
- INTEGER 作为 Unix 时间，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这些格式存储日期和时间，并使用内置的日期和时间函数在格式之间自由转换.
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.
如果您只需要秒精度，请使用 Unix 时间格式的整数.否则，对小数秒使用浮点数.
If you need only seconds precision, use integers in Unix Time format. Otherwise, use floating-pointer numbers for fractional seconds.
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