slinkydeveloper commented on a change in pull request #17256:
URL: https://github.com/apache/flink/pull/17256#discussion_r709199542
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File path: docs/data/sql_functions.yml
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@@ -516,7 +516,14 @@ conditional:
- sql: NULLIF(value1, value2)
description: Returns NULL if value1 is equal to value2; returns value1
otherwise. E.g., NULLIF(5, 5) returns NULL; NULLIF(5, 0) returns 5.
- sql: COALESCE(value1, value2 [, value3]*)
- description: Returns the first value that is not NULL from value1, value2,
.... E.g., COALESCE(NULL, 5) returns 5.
+ description: |
+ Coalesce specifies a series of expressions, and returns the first
expression whose value is not null.
+
+ If all the expressions evaluate as null, coalesce returns a null value.
+ The return type of the coalesce function is the least common type among
its arguments, and it's nullable if all its arguments are nullable.
+
+ E.g. COALESCE(NULL, "-") returns "-".
+ E.g. COALESCE(f0, f1, "-") returns the first non-null value among f0 and
f1, if both are null returns "-".
Review comment:
Looks good to me
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