Скачать или смотреть How to Convert DATE Columns to DATETIME in BigQuery

Learn how to seamlessly convert your `DATE` columns to `DATETIME` format in BigQuery using simple SQL functions. This guide will help you enhance your data representation effortlessly.
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Converting DATE Columns to DATETIME in BigQuery

When working with data in Google BigQuery, you may encounter situations where you need to combine DATE columns with time information to generate DATETIME values. This guide will guide you through a solution for adding a time component to your DATE columns for a cleaner and more uniform data representation.

The Problem

Let’s say you have two tables containing MIN and MAX DATE columns (in the format YYYY-MM-DD), and you want to create additional columns that represent these dates as DATETIME, including a default time of 00:00:00. Having this time component is particularly useful for maintaining consistency across your datasets, even if the time values don't hold significant meaning in your context.

Your current SQL query looks something like this:

[[See Video to Reveal this Text or Code Snippet]]

Now, let’s look at how you can add corresponding DATETIME columns for both visit_start_date and visit_end_date.

The Solution

To convert your DATE columns into DATETIME, you can use either the CAST() function or the DATETIME() function in SQL. Below is a step-by-step explanation of how to implement this.

Step 1: Utilizing the CAST() Function

You can cast the DATE columns directly as DATETIME like so:

[[See Video to Reveal this Text or Code Snippet]]

This casts the least date value as a DATETIME, effectively appending a time of 00:00:00.

Step 2: Using the DATETIME() Function

Alternatively, you can achieve the same result with the DATETIME() function, which provides a more explicit conversion:

[[See Video to Reveal this Text or Code Snippet]]

This command also results in a DATETIME object and ensures the time defaults to midnight.

Updated Query

Here’s how your modified query would look with these changes incorporated:

[[See Video to Reveal this Text or Code Snippet]]

Desired Output

After making these adjustments, your output will include:

person_idvisit_start_datevisit_start_datetimevisit_end_datevisit_end_datetime1234YYYY-MM-DDYYYY-MM-DD 00:00:00YYYY-MM-DDYYYY-MM-DD 00:00:00Conclusion

By following these steps, you can effectively convert DATE columns into DATETIME format in Google BigQuery, adding a time component that enhances the uniformity and usability of your dataset.

Now, go ahead and implement these changes in your SQL queries for better data representation in your projects!