When working with DuckDB, sometimes we might need to get the weekday name from a date or timestamp value. And sometimes we might want just the abbreviated weekday name, rather than the full name. For example, we might want Mon instead of Monday.
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Fix “Could not convert string ‘…’ to INT64” When Using the GENERATE_SUBSCRIPTS() Function in DuckDB
If you’re getting an error that reads something like “Could not convert string ‘…’ to INT64” when using the generate_subscripts() function in DuckDB, it appears that your second argument is a string, when it should be an integer.
DuckDB’s generate_subscripts() function accepts two arguments; the array as the first argument, and the dimension as the second argument. The second argument must be INT64 (or be able to be implicitly converted to that type). Passing the wrong data type as the second argument can cause the above error to occur.
To fix this issue, make sure that the second argument is compatible with INT64.
Adding Quotes Around Field Values When Outputting DuckDB Query Results as a List
In this article we look at how to automatically enclose values in single quotes when outputting DuckDB query results as a list. Using this method, each value is formatted as SQL literals. This can be useful when you want to escape the values for SQL or for some other purpose.
We also look at how CSV output is sometimes quoted with double quotes, and how we can adjust the results by doing things like removing the headers and changing the list separator.
4 Ways to Check Your DuckDB Version
If you’re using DuckDB and you need to check which version you’re running, here are some quick and easy methods to do so.
Sampling Rows from a Table in DuckDB with the SAMPLE Clause
DuckDB’s SAMPLE clause is a handy feature that allows us to work with a random subset of our data. This is particularly useful when dealing with large datasets where processing the entire dataset might be time-consuming or unnecessary for exploratory data analysis, testing queries, or creating representative samples.
When we use this clause, we can specify the absolute number of rows to return, or a percentage of rows. We also have an option of sampling method to use.
Find Out if a Table is WITHOUT ROWID in SQLite
One of SQLite’s unique features is the WITHOUT ROWID table, which can be used to optimize performance and storage in specific scenarios.
While it’s easy enough to create a WITHOUT ROWID table (just add WITHOUT ROWID to the definition), how to identify a WITHOUT ROWID table might not be so obvious.
In this article, we’ll start by briefly revising what WITHOUT ROWID tables are and how they differ from ordinary tables. Then we’ll look at how to identify these tables by using SQLite’s PRAGMA commands.
Fixing “Conversion Error” When Using COALESCE() in DuckDB
If you’re getting an error that reads “Conversion Error: Could not convert …etc” while using the COALESCE() function in DuckDB, it appears that you’re using arguments with incompatible types.
To fix this issue, try using CAST() or TRY_CAST() to ensure that all arguments are compatible. Alternatively, make sure the arguments to COALESCE() are of the same type (or at least, compatible types).
Using TRY_STRPTIME() to Handle Errors When Constructing Timestamps in DuckDB
If you’ve ever used the strptime() function to create a timestamp in DuckDB, you may be aware that it will return an error if it can’t construct the timestamp from the format string/s provided.
While such an error could be useful in some situations, it could also be annoying in others.
Fortunately, DuckDB also provides the try_strptime() function, which will suppress any error that we might ordinarily get in such cases. This function returns null instead of an error.
Using the AGE() Function to Compare Dates in DuckDB
When working with date and time data in DuckDB, calculating the difference between two dates is a common requirement. Whether we’re determining a person’s age from their birthdate or measuring the duration between two events, DuckDB’s age() function provides a straightforward solution. This function returns an interval representing the difference between two timestamps or dates, making it especially useful for time-based analyses.
In this article, we’ll explore how to use the age() function in DuckDB. We’ll cover its syntax, and provide some simple examples.