How do DATETIME values work in SQLite?

Question

SQlite does not have a specific datetime type. You can use TEXT, REAL or INTEGER types, whichever suits your needs.

Straight from the DOCS

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 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.

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.

SQLite built-in Date and Time functions can be found here.

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 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. 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.

Having said that, I would use INTEGER and store seconds since Unix epoch (1970-01-01 00:00:00 UTC).

One of the powerful features of SQLite is allowing you to choose the storage type. Advantages/disadvantages of each of the three different possibilites:

• ISO8601 string

  • String comparison gives valid results
  • Stores fraction seconds, up to three decimal digits
  • Needs more storage space
  • You will directly see its value when using a database browser
  • Need for parsing for other uses
  • "default current_timestamp" column modifier will store using this format

• Real number

  • High precision regarding fraction seconds
  • Longest time range

• Integer number

  • Lowest storage space
  • Quick operations
  • Small time range
  • Possible year 2038 problem

If you need to compare different types or export to an external application, you're free to use SQLite's own datetime conversion functions as needed.

For practically all date and time matters I prefer to simplify things, very, very simple... Down to seconds stored in integers.

Integers will always be supported as integers in databases, flat files, etc. You do a little math and cast it into another type and you can format the date anyway you want.

Doing it this way, you don't have to worry when [insert current favorite database here] is replaced with [future favorite database] which coincidentally didn't use the date format you chose today.

It's just a little math overhead (eg. methods--takes two seconds, I'll post a gist if necessary) and simplifies things for a lot of operations regarding date/time later.