Github user twalthr commented on a diff in the pull request: https://github.com/apache/flink/pull/4404#discussion_r131633926 --- Diff: docs/dev/table/sql.md --- @@ -497,6 +497,23 @@ FROM ( {% endhighlight %} </td> </tr> + + <tr> + <td> + <strong>In</strong><br> + <span class="label label-primary">Batch</span> + </td> + <td> + Returns true if an expression exists in a given table sub-query. The sub-query table must consist of one column. This column must have the same data type as the expression. --- End diff -- What do you mean with "enhanced"? We cannot change the SQL standard. The user can nest another query and reduce the table to one column.
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