Date/time types in BigQuery

Introduction to BigQuery

Matt Forrest

Field CTO

Why date and times matter

Easily filter long datasets
Extract parts of dates/times
Partitioning strategies

Dates

Example of the DATE data type

SELECT 
    DATE(2010, 05, 19) as launch


/*------------*
 | launch     |
 +------------+
 | 2010-05-19 |
 *------------*/

Timestamps

Example timestamp:

SELECT 
    TIMESTAMP("2010-05-19 00:00:00+00") as launch


/*-------------------------*
 | launch                  |
 +-------------------------+
 | 2010-05-19 00:00:00 UTC |
 *-------------------------*/

Datetime and Time

Examples of time and datetime:

SELECT
  TIME(12, 00, 00) as noon,

  DATETIME(2019, 05, 19, 00, 00, 00) as launch


/*----------+----------------------*
 | noon     | launch               |
 +----------+----------------------+
 | 12:00:00 | 2019-05-19T00:00:00  |
 *----------+----------------------*/

Date and timestamp parts

Day

DAY, DAYOFWEEK, DAYOFYEAR.

Week

WEEK, WEEKDAY, ISOWEEK.

Month/Year

MONTH, QUARTER, YEAR, ISOYEAR.

Time

HOUR, MINUTE, SECOND, MILLISECOND, MICROSECOND.

¹ https://cloud.google.com/bigquery/docs/reference/standard-sql/timestamp_functions#timestamp_trunc

ADD, SUBTRACT, and DIFF

Adding five days

SELECT 
    DATE_ADD(DATE '2010-05-19', 
             INTERVAL 5 DAY) 
             AS five_days_later;


/*--------------------*
 | five_days_later    |
 +--------------------+
 | 2010-05-24         |
 *--------------------*/

Finding the difference

SELECT 
    DATE_DIFF(DATE '2010-05-24', 
             DATE '2010-05-19', DAY) 
             AS difference;


/*-------------*
 | difference  |
 +-------------+
 | 5           |
 *-------------*/

EXTRACT

Finding the day of the week

SELECT 
    EXTRACT(DAYOFWEEK FROM DATE '2010-05-19') 
             AS day_of_week;


/*--------------*
 | day_of_week  |
 +--------------+
 | 4            |
 *--------------*/

FORMAT

SELECT
    FORMAT_DATE(
      '%x', DATE '2010-05-19') 
    AS with_slashes;


/*--------------*
 | with_slashes |
 +--------------+
 | 05/19/10     |
 *--------------*/

SELECT
    FORMAT_DATE(
      '%A', DATE '2010-05-19') 
    AS dow;


/*--------------*
 | dow          |
 +--------------+
 | Wednesday    |
 *--------------*/

¹ https://cloud.google.com/bigquery/docs/reference/standard-sql/format-elements#format_elements_date_time

Current date/timestamp

Finding the current timestamp:

SELECT
  CURRENT_TIMESTAMP(); 

/*---------------------------------*
 | current_timestamp               |
 +---------------------------------+
 | 2023-11-13 17:35:25.951432 UTC  |
 *---------------------------------*/

Finding the current date:

SELECT
  CURRENT_DATE();

/*---------------*
 | current_date  |
 +---------------+
 | 2023-11-13    |
 *---------------*/

Cheat sheet

Data types

Dates are exact days, timestamps are absolute dates and times

Date/timestamp parts

Parts of a date/timestamp (e.g. MONTH, or HOUR)

Add and subtract

Functions to add or subtract date parts (e.g. DATE_ADD)

Difference

Difference between two dates by date part (e.g. TIMESTAMP_SUB)

Extract and format

Extract a part of a date using date parts, format a date (e.g. EXTRACT and FORMAT)

Current date/timestamp

Return the current date or timestamp (e.g. CURRENT_TIMESTAMP)

Let's practice!

Introduction to BigQuery