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Can a field in BigQuery have NULLABLE and REPEATED mode? For example to represent an array of strings, where some strings might be NULL.
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A RECORD column can have REPEATED mode, which is represented as an array of STRUCT types. Also, a field within a record can be repeated, which is represented as a STRUCT that contains an ARRAY . An array cannot contain another array directly. For more information, see Declaring an ARRAY type.
BigQuery supports some Modes. These are particularly: Nullable, Required, Repeated. In the Nullable Mode, null values are allowed. The Required Mode doesn't allow any null value. Finally, the Repeated Mode contains an array of values of the specified type in the column.
How to Query BigQuery Repeated Fields. To extract information from a repeated field in BigQuery, you must use a more exotic pattern. This is normally done using the UNNEST function, which converts an array of values in a table into rows. These can then be joined to the original table to be queried.
BigQuery Nested and Repeated Fields. Nested Fields. A STRUCT or RECORD contains ordered fields each with a type and field name. You can define one or more of the child columns as STRUCT types, referred to as nested STRUCT s (up to 15 levels of nesting).
Can a field in BigQuery have NULLABLE and REPEATED mode?
Nope. Either one or another
ARRAYs cannot be NULL. NULL ARRAY elements cannot persist to a table.
See more in Data Types
For example to represent an array of strings, where some strings might be NULL.
Simple example below shows that Array cannot have a null element;
#standardSQL
WITH test AS (
SELECT ['abc', NULL, 'xyz']
)
SELECT *
FROM test
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