Calling the UDF in a query

After registration of a UDF, you do not need to restart Hive before using the UDF in a query. In this example, you call the UDF you created in a SELECT statement, and Hive returns the data type of a column you specify.

For the example query in this task, you need to create a table in Hive and insert some data.

This task assumes you have the following example table in Hive:

+------------------+---------------+---------------+
|  students.name   | students.age  | students.gpa  |
+------------------+---------------+---------------+
| fred flintstone  | 35            | 1.28          |
| barney rubble    | 32            | 2.32          |
+------------------+---------------+---------------+

As a user, you need to have permission to call a UDF, which a Ranger policy can provide.

Use the database in which you registered the UDF.
```
USE default;
```

Query Hive using the direct reference method:

SELECT students.name, udftypeof(students.name) AS type FROM students WHERE age=35;

You get the data type of the name column in the students table:

+------------------+----------------------------------------------------+
|  students.name   |                        type                        |
+------------------+----------------------------------------------------+
| fred flintstone  | Type: org.apache.hadoop.hive.serde2.io.HiveVarcharWritable |
+------------------+----------------------------------------------------+