yanghua commented on a change in pull request #6432: [FLINK-9970] [table] Add
ASCII/CHR function for table/sql API
URL: https://github.com/apache/flink/pull/6432#discussion_r226515985
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala
##########
@@ -252,6 +252,17 @@ object ScalarFunctions {
regexp_extract(str, regex, 0)
}
+ /**
+ * Returns a numeric value of the leftmost character of the string str.
+ */
+ def ascii(str: String): Integer = {
+ if (str == null || str.equals("")) {
+ 0
Review comment:
OK, I can return `null`. In the Java world, Integer is an object, and
returning null is fine from a grammatical and semantic point of view. However,
when we use ascii('') as input to other operators, such as
xxxFunction(ascii('')). The subsequent effects of null and 0 are completely
different. Null may produce NPE or other behavior, while 0 is different. If you
have already considered this, then I have no problem here.
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