You will love this blog because date functions and formatting differ dramatically between databases, but I have covered that with brilliant examples and clear and concise explanations below.

All of these examples have come from my books and training classes. Please do me a favor and tell your training coordinator that you know the best technical trainer in the world. Ask them to hire me to train at your company, either on-site or with a virtual class. They can see our classes, outlines, and a sample of my teaching at this link on our website.

https://coffingdw.com/education/


Below the video are great date functions on Google BiqQuery. However, you can first witness a two-minute video that joins a BigQuery table with tables from Databricks, Snowflake, Redshift, Azure Synapse, Vertica, Teradata, Oracle, SQL Server, DB2, Yellowbrick, MySQL, Postgres, Microsoft Access, and Excel in a single federated query.

Below are the keywords to get the date, time, and timestamp. These are reserved words that the system will deliver to you when requested.

Add or subtract a number from a date, and you are adding or subtracting days.

The query example below shows how the date is constructed in the year, month, and day. It also shows how the DATE command extracts the date portion from a timestamp.  Finally, notice the third date is December 31st, but because of the use of the timezone, the extract date is December 30th.

The examples below show you how to format dates.

The Extract command extracts portions of a date, time, or timestamp.

The below examples show how robust the EXTRACT command is at extracting portions of a date, time, or timestamp. We also use the CASE logic to determine the day of the week.

DATE_DIFF returns the number of the whole specified date_part intervals between two dates.

DATE_TRUNC truncates the date to the specified granularity, such as Day, Week, Week, Month, Quarter, Year, ISOWEEK, and ISOYEAR. Below, we have the date of ‘2023-05-05’ and return the dates at the beginning of the month, year, quarter, and the previous Monday.

The DATE_ADD will take an interval and add it to the date. Above, our example is adding different criteria for five days, one month, and two years to the current date. Special handling is done automatically for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original date’s day, the result day is the last day of the new month.

The example below displays the current_date and the first or last day of other months. We have the month’s first and final day, the previous month’s last day, and the next month’s first day.

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