DESCRIBE QUERY
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
SELECTstatement - a
CTE(Common table expression)statement - an
INLINE TABLEstatement - a
TABLEstatement - a
FROMstatement`
Please refer to select-statement for a detailed syntax of the query parameter.
- a
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|
+--------+---------+----------+