Unnesting Lists & Structs with DuckDB’s UNNEST() Function

DuckDB has an unnest() function that we can use to unnest lists and structs. Well, it can also be applied to NULL, but that’ll return an empty result.

By “unnest” I mean it takes the list or struct, and it returns its contents as rows in a table. You might say that it converts lists and structs into tables, where each item in the list or struct becomes a row in the table.

Below are examples of using DuckDB’s unnest() function to unnest lists and structs.

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Fix ‘Binder Error: ‘list_has_all’ cannot compare lists of different types’ in DuckDB

If you’re getting an error that reads “Binder Error: ‘list_has_all’ cannot compare lists of different types” in DuckDB, it appears that you’re passing two different types of lists to the list_has_all() function.

DuckDB’s list_has_all() function accepts two lists as arguments. These need to be of the same type.

To fix this issue, make sure that both lists are of the same type.

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Fix “Sample method … cannot be used with a discrete sample count” When Using the SAMPLE Clause in DuckDB

If you’re getting an error that reads something like “Sample method System cannot be used with a discrete sample count” when using the SAMPLE clause in DuckDB, it looks like you’re specifying an invalid sampling method for the context with which you’re using the SAMPLE clause. Perhaps you’re using system or bernoulli, when you should be using reservoir.

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Check if a Sub-List Appears in a Larger List in DuckDB: LIST_HAS_ALL()

When working with lists in DuckDB, we sometimes need to check whether a list contains specific elements. The list_has_all() function is a handy tool that allows us to verify if all elements of one list exist within another. This function is particularly useful in filtering queries, data validation, and advanced list-based operations.

In this article, we’ll explore how list_has_all() works in DuckDB.

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