Appending values to lists is a common task when working with DuckDB and other DBMSs (not to mention programming languages in general). Usually we’ll get a function that’s purpose built for the task. As it turns out, DuckDB provides us with at least three functions to do this task.
how to
3 Functions for Extracting a Value from a List in DuckDB
DuckDB provides us with a list_extract() function that extracts a value from a list, based on the element’s index in that list.
But as if one function isn’t enough, it also provides us with a couple of aliases that we can use instead of list_extract() if we prefer.
So let’s call it three functions that we can use to extract a value from a list.
Generating Date Ranges with DuckDB Queries
Working with date ranges is a common requirement in data analysis, reporting, and time-series operations. DuckDB provides us with several approaches for generating date ranges. This article explores various techniques for creating date ranges in DuckDB.
6 Functions for Working with the Unix Epoch in DuckDB
DuckDB offers a versatile set of functions to handle timestamps at various levels of precision. This article explores some of DuckDB’s functions that help us to convert between epoch representations and timestamps.
These specialized time conversion functions can be handy tools when working with temporal data, allowing seamless translation between human-readable timestamps and machine-optimized epoch representations at varying levels of precision.
2 Functions that Create a List in DuckDB
DuckDB provides us with plenty of functions for working with lists, including a couple that actually create lists for us.
In particular, the list_value() and list_pack() functions are specifically for creating lists in DuckDB. We’ll run through some examples of these functions below.
5 Ways to Convert a List to a String in DuckDB
If we have a list in DuckDB, and we want to convert it to a string, there are a number of options on the table. Basically, what we want to do is combine/concatenate all elements into a single string. Let’s take a look at five ways to convert a list to a string in DuckDB.
Output Query Results as a Tab-Separated List in DuckDB
DuckDB’s command-line interface (CLI) provides a simple built-in method for outputting query results as tab-separated values (TSV) using the .mode tabs command.
This article takes a quick look at this output mode and explores some of the options available for when outputting query results as a tab-separated list.
Parse and Minify JSON with DuckDB’s JSON() Function
One of the many JSON functions that DuckDB provides is the json() function, which parses and minifies JSON values. We pass the JSON data to the function, and it parses and minifies the JSON, then returns the result.
Get the Day Name from a Date in DuckDB
DuckDB provides us with a couple of ways to get the weekday name from a date or timestamp value. This could be the full day name, such as Monday, or the short/abbreviated day name, such as Mon.
Here are two ways to return the day name from a date in DuckDB.
Using JSON_KEYS() in DuckDB to Get the Keys in a JSON Document
DuckDB has a json_keys() function that we can use to extract the keys from a JSON object. It returns the keys as a list of strings (LIST of VARCHAR).