sunjincheng121 commented on a change in pull request #8057:
[FLINK-12028][table] Add `addColumns`,`renameColumns`, `dropColumns` …
URL: https://github.com/apache/flink/pull/8057#discussion_r270342816
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File path: docs/dev/table/tableApi.md
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@@ -188,7 +188,50 @@ Table result = orders.select("*");
{% endhighlight %}
</td>
</tr>
-
+ <tr>
+ <td>
+ <strong>AddColumns</strong><br>
+ <span class="label label-primary">Batch</span> <span class="label
label-primary">Streaming</span>
+ </td>
+ <td>
+ <p>Performs a field add operation.</p>
+{% highlight java %}
+Table orders = tableEnv.scan("Orders");
+Table result = orders.addColumns("concat(c, 'sunny')");
+{% endhighlight %}
+ <p>You can also replace existing fields, the following example
will replace the
+ existing `desc` field </p>
+{% highlight java %}
+Table result = orders.addColumns(true, "concat(c, 'sunny') as desc");
+{% endhighlight %}
+ </td>
+ </tr>
+ <tr>
+ <td>
+ <strong>DropColumns</strong><br>
+ <span class="label label-primary">Batch</span> <span
class="label label-primary">Streaming</span>
+ </td>
+ <td>
+ <p>Performs a field drop operation.</p>
+{% highlight java %}
+Table orders = tableEnv.scan("Orders");
+Table result = orders.dropColumns("b, c");
+{% endhighlight %}
+ </td>
+ </tr>
+ <tr>
+ <td>
+ <strong>RenameColumns</strong><br>
+ <span class="label label-primary">Batch</span> <span
class="label label-primary">Streaming</span>
+ </td>
+ <td>
+ <p>Performs a field rename operation.</p>
+{% highlight java %}
+Table orders = tableEnv.scan("Orders");
+Table result = orders.renameColumns("b as b2, c as c2");
Review comment:
That good point, I had thought this case, I think we should throw the
exception if the renamed `name` already exists. In common case, the user wants
to rename a meaningful `name` for their business. but not want replace exist
one, if user want replace exist one, the will drop the exist by dropColumns,
what do you think?
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