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https://issues.apache.org/jira/browse/FLINK-3579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15217848#comment-15217848
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ASF GitHub Bot commented on FLINK-3579:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/1821#discussion_r57876138
--- Diff:
flink-libraries/flink-table/src/test/java/org/apache/flink/api/java/table/test/StringExpressionsITCase.java
---
@@ -121,6 +120,66 @@ public void testNonWorkingSubstring2() throws
Exception {
resultSet.collect();
}
+ @Test
+ public void testStringConcat() throws Exception {
+ ExecutionEnvironment env =
ExecutionEnvironment.getExecutionEnvironment();
+ TableEnvironment tableEnv = new TableEnvironment();
+
+ DataSet<Tuple2<String, Integer>> ds = env.fromElements(
+ new Tuple2<>("ABCD", 3),
+ new Tuple2<>("ABCD", 2));
+
+ Table in = tableEnv.fromDataSet(ds, "a, b");
+
+ Table result = in
+ .select("a + b + 42");
--- End diff --
Maybe you need to rethink your approach. Expressions like `a +
42.abs().cast(STRING)` also do not work. It might be necessary to introduce a
modified grammar where the dot is special symbol followed by symbols for
`cast`, functions etc. without a dot.
> Improve String concatenation
> ----------------------------
>
> Key: FLINK-3579
> URL: https://issues.apache.org/jira/browse/FLINK-3579
> Project: Flink
> Issue Type: Bug
> Components: Table API
> Reporter: Timo Walther
> Assignee: ramkrishna.s.vasudevan
> Priority: Minor
>
> Concatenation of a String and non-String does not work properly.
> e.g. {{f0 + 42}} leads to RelBuilder Exception
> ExpressionParser does not like {{f0 + 42.cast(STRING)}} either.
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