Database Management Systems
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.
DuckDB provides us with a json_transform_strict() function that works just like the json_transform() function, except that it throws an error when type casting fails. The json_transform() function on the other hand, returns NULL for the respective field in such cases.
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.
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.
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.
As with most other database management systems (DBMSs), DuckDB provides us with a way of finding the position of an element in a list. This is the index at which the specified element occurs in the list.
Actually, DuckDB provides us with four synonymous functions for doing this (i.e. they all do the same thing).
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.
DuckDB offers two primary functions for type conversion: cast() and try_cast(). While they serve similar purposes, their behavior when handling invalid conversions differs significantly, which can greatly impact our data processing workflows.
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).
Most SQL developers are familiar with the min() function that allows us to get the minimum value from a data set. But if we want to get the minimum value from a list, passing the list to the min() function won’t quite cut it. But don’t despair! Finding the minimum value in a list is just as easy. Here are three ways to do it. And yes, we can even use the min() function if we want.