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https://issues.apache.org/jira/browse/FLINK-9970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16560643#comment-16560643
]
ASF GitHub Bot commented on FLINK-9970:
---------------------------------------
yanghua commented on a change in pull request #6432: [FLINK-9970] Add ASCII/CHR
function for table/sql API
URL: https://github.com/apache/flink/pull/6432#discussion_r205934831
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala
##########
@@ -196,9 +196,35 @@ object ScalarFunctions {
new String(data)
}
+ /**
+ * Returns the numeric value of the leftmost character of the string str.
+ * Returns 0 if str is the empty string. Returns NULL if str is NULL.
+ */
+ def ascii(str: String): String = {
+ if (str == null) {
+ null
+ } else if (str.equals("")) {
+ ""
+ } else {
+ str.charAt(0).toByte.toString
+ }
+ }
+
/**
* Returns the base string decoded with base64.
*/
def fromBase64(str: String): String = new String(Base64.decodeBase64(str))
+ /**
+ * Returns string contains a character which converts from a ASCII integer.
+ * If the ASCII less then 0 or greater than 255, return null.
+ */
+ def chr(ascii: Integer): String = {
Review comment:
hi @hequn8128 others has accepted and fixed except this. can you give a
hint? you mean:
* one function and the parameter support multiple types? if support I can
you Either[Type1, Type2], but more than two, how to handle this? I am not very
familiar with Scala.
* multiple functions, one support a single type?
* assume supported these types, the `OperandTypes.NUMERIC` can represent
them?
```scala
val CHR = new SqlFunction(
"CHR",
SqlKind.OTHER_FUNCTION,
ReturnTypes.cascade(ReturnTypes.explicit(SqlTypeName.VARCHAR),
SqlTypeTransforms.TO_NULLABLE),
null,
OperandTypes.NUMERIC,
SqlFunctionCategory.STRING
)
```
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> Add ASCII/CHR function for table/sql API
> ----------------------------------------
>
> Key: FLINK-9970
> URL: https://issues.apache.org/jira/browse/FLINK-9970
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: vinoyang
> Assignee: vinoyang
> Priority: Minor
> Labels: pull-request-available
>
> for ASCII function :
> refer to :
> [https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_ascii]
> for CHR function :
> This function convert ASCII code to a character,
> refer to : [https://doc.ispirer.com/sqlways/Output/SQLWays-1-071.html]
> Considering "CHAR" always is a keyword in many database, so we use "CHR"
> keyword.
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