layout: global title: DESCRIBE QUERY displayTitle: DESCRIBE QUERY license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

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Description

The DESCRIBE QUERY statement is used to return the metadata of output of a query. A shorthand DESC may be used instead of DESCRIBE to describe the query output.

Syntax

{ DESC | DESCRIBE } [ QUERY ] input_statement

Parameters

  • QUERY This clause is optional and may be omitted.

  • input_statement

    Specifies a result set producing statement and may be one of the following:

    • a SELECT statement
    • a CTE(Common table expression) statement
    • an INLINE TABLE statement
    • a TABLE statement
    • a FROM statement`

    Please refer to select-statement for a detailed syntax of the query parameter.

Examples

-- Create table `person`
CREATE TABLE person (name STRING , age INT COMMENT 'Age column', address STRING);

-- Returns column metadata information for a simple select query
DESCRIBE QUERY SELECT age, sum(age) FROM person GROUP BY age;
+--------+---------+----------+
|col_name|data_type|   comment|
+--------+---------+----------+
|     age|      int|Age column|
|sum(age)|   bigint|      null|
+--------+---------+----------+

-- Returns column metadata information for common table expression (`CTE`).
DESCRIBE QUERY WITH all_names_cte
    AS (SELECT name from person) SELECT * FROM all_names_cte;
+--------+---------+-------+
|col_name|data_type|comment|
+--------+---------+-------+
|    name|   string|   null|
+--------+---------+-------+

-- Returns column metadata information for an inline table.
DESC QUERY VALUES(100, 'John', 10000.20D) AS employee(id, name, salary);
+--------+---------+-------+
|col_name|data_type|comment|
+--------+---------+-------+
|      id|      int|   null|
|    name|   string|   null|
|  salary|   double|   null|
+--------+---------+-------+

-- Returns column metadata information for `TABLE` statement.
DESC QUERY TABLE person;
+--------+---------+----------+
|col_name|data_type|   comment|
+--------+---------+----------+
|    name|   string|      null|
|     age|      int| Agecolumn|
| address|   string|      null|
+--------+---------+----------+

-- Returns column metadata information for a `FROM` statement.
-- `QUERY` clause is optional and can be omitted.
DESCRIBE FROM person SELECT age;
+--------+---------+----------+
|col_name|data_type|   comment|
+--------+---------+----------+
|     age|      int| Agecolumn|
+--------+---------+----------+

Related Statements