One of the aggregate functions available in DuckDB is the FIRST() function, which returns the first value from each group in a query.
Let’s take a look at some examples of using the FIRST() function in DuckDB
DBMS
Database Management Systems
Fix “Unrecognized format for strftime/strptime: %” in DuckDB
If you’re getting an error that includes the text “Unrecognized format for strftime/strptime: %” in DuckDB, it appears that you’re including an unescaped percent sign (%) in your format string when using a function like strftime() or strptime().
Whenever we need a percent sign to be included in the formatted output, we must escape it with another percent sign in the format string.
So to fix this issue, try escaping the percent sign with another percent sign.
Add Hours to a Date/Time Value in DuckDB
DuckDB provides us with a range of functions and operators that we can use to manipulate date, time, and timestamp values. One basic operation you might find yourself having to perform is date/time arithmetic, such as adding one or more hours to a date/time value.
Below are two methods we can use in order to add one or more hours to a date, timestamp, or time value.
Why SQLite Allows NULL Values in Primary Key Columns
SQLite, one of the most widely used database engines, is known for its lightweight design, ease of use, and adherence to most aspects of the SQL standard. However, one notable deviation from the standard lies in its handling of PRIMARY KEY constraints. Unlike the SQL standard, SQLite allows NULL values in primary key columns in some cases.
Let’s look at the reasons behind this behavior, and explore the implications of NULL values in primary key columns. We’ll also examine SQLite’s treatment of NULL values as distinct for uniqueness constraints.
Using the .nullvalue Command to See NULL Output in the DuckDB CLI
By default, when a query returns a null value in the DuckDB command line interface (CLI), an empty string is displayed. This may or may not be what you want. But if you’re like me, you probably want DuckDB to explicitly tell you that it’s a null value. After all, if an empty string is returned, perhaps the data contained an empty string?
Fortunately, DuckDB provides us with the .nullvalue dot command so that we can change the output of null values.
Formatting Dates with STRFTIME() in DuckDB
In DuckDB, the strftime() function is a handy tool for formatting date and timestamp values as strings. It accepts the date/timestamp value and a format string as arguments. The function then returns the date/time in the format provided by the format string.
7 Functions that Return the Current Date in DuckDB
DuckDB provides us with a bunch of functions that we can use to return the current date and/or time. We can get the date in local time or coordinated universal time (UTC), depending on the function we use. These can be useful in a range of scenarios, such logging the current date in a database column, or filtering or comparing dates based on the current date.
Understanding the STRPTIME() Function in DuckDB
DuckDB provides us with a good selection of date/time functions. The strptime() function is a useful one for times where you need to convert a date string into a valid timestamp value; its sole purpose is to parse strings into timestamps.
In this article, we’ll look at how the strptime() function works, along with some examples to demonstrate.
Fix “Error: Month out of range, expected a value between 1 and 12” when using strptime() in DuckDB
If you’re getting an error that reads “Error: Month out of range, expected a value between 1 and 12” when using the strptime() function in DuckDB, it could be that you’re getting your months mixed up in your format string.
A Quick Look at the SUM() Function in DuckDB
One of the more commonly used aggregate functions in SQL databases is the sum() function, which provides an easy way to calculate the total sum of a numeric column. DuckDB is no exception.
In this article, we’ll explore how the sum() function works in DuckDB, along with some straightforward examples to demonstrate.