Github user vasia commented on a diff in the pull request:
https://github.com/apache/flink/pull/1939#discussion_r61098440
--- Diff: docs/apis/batch/libs/table.md ---
@@ -67,6 +67,165 @@ The central concept of the Table API is a `Table` which
represents a table with
The following sections show by example how to use the Table API embedded
in the Scala and Java DataSet APIs.
+### Registering Tables to and Accessing Tables from TableEnvironments
+
+`TableEnvironment`s have an internal table catalog to which tables can be
registered with a unique name. After registration, a table can be accessed from
the `TableEnvironment` by its name. Tables can be registered in different ways.
+
+#### Register a DataSet
+
+A `DataSet` is registered as a `Table` in a `BatchTableEnvironment` as
follows:
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
+BatchTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env);
+
+// register the DataSet cust as table "Customers" with fields derived from
the dataset
+tableEnv.registerDataSet("Customers", cust)
+
+// register the DataSet ord as table "Orders" with fields user, product,
and amount
+tableEnv.registerDataSet("Orders", ord, "user, product, amount");
+{% endhighlight %}
+</div>
+
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+val env = ExecutionEnvironment.getExecutionEnvironment
+val tableEnv = TableEnvironment.getTableEnvironment(env)
+
+// register the DataSet cust as table "Customers" with fields derived from
the dataset
+tableEnv.registerDataSet("Customers", cust)
+
+// register the DataSet ord as table "Orders" with fields user, product,
and amount
+tableEnv.registerDataSet("Orders", ord, 'user, 'product, 'amount)
+{% endhighlight %}
+</div>
+</div>
+
+*Note: DataSet table names are not allowed to follow the
`^_DataSetTable_[0-9]+` pattern, as these are reserved for internal use only.*
+
+#### Register a DataStream
+
+A `DataStream` is registered as a `Table` in a `StreamTableEnvironment` as
follows:
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
+StreamTableEnvironment tableEnv =
TableEnvironment.getTableEnvironment(env);
+
+// register the DataStream cust as table "Customers" with fields derived
from the datastream
+tableEnv.registerDataStream("Customers", cust)
+
+// register the DataStream ord as table "Orders" with fields user,
product, and amount
+tableEnv.registerDataStream("Orders", ord, "user, product, amount");
+{% endhighlight %}
+</div>
+
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+val env = StreamExecutionEnvironment.getExecutionEnvironment
+val tableEnv = TableEnvironment.getTableEnvironment(env)
+
+// register the DataStream cust as table "Customers" with fields derived
from the datastream
+tableEnv.registerDataStream("Customers", cust)
+
+// register the DataStream ord as table "Orders" with fields user,
product, and amount
+tableEnv.registerDataStream("Orders", ord, 'user, 'product, 'amount)
+{% endhighlight %}
+</div>
+</div>
+
+*Note: DataStream table names are not allowed to follow the
`^_DataStreamTable_[0-9]+` pattern, as these are reserved for internal use
only.*
+
+#### Register a Table
+
+A `Table` that originates from a Table API operation or a SQL query is
registered in a `TableEnvironemnt` as follows:
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+// works for StreamExecutionEnvironment identically
+ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
+BatchTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env);
+
+// convert a DataSet into a Table
+Table custT = tableEnv
+ .toTable(custDs, "name, zipcode")
+ .where("zipcode = '12345'")
+ .select("name")
+
+// register the Table custT as table "custNames"
+tableEnv.registerTable("custNames", custT)
+{% endhighlight %}
+</div>
+
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+// works for StreamExecutionEnvironment identically
+val env = ExecutionEnvironment.getExecutionEnvironment
+val tableEnv = TableEnvironment.getTableEnvironment(env)
+
+// convert a DataSet into a Table
+val custT = custDs
+ .toTable(tableEnv, 'name, 'zipcode)
+ .where('zipcode === "12345")
+ .select('name)
+
+// register the Table custT as table "custNames"
+tableEnv.registerTable("custNames", custT)
+{% endhighlight %}
+</div>
+</div>
+
+A registered `Table` that originates from a Table API operation or SQL
query is treated similarly as a view as known from relational DBMS, i.e., it
can be inlined when optimizing the query.
+
+#### Register an external table using a TableSource
--- End diff --
Capitalize Table to be consistent with previous titles?
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