クエリの記述 (SQL Analytics)DESCRIBE QUERY (SQL Analytics)

クエリの出力のメタデータを返します。Returns the metadata of output of a query.

構文Syntax

{ DESC | DESCRIBE } [ QUERY ] input_statement

パラメーターParameters

  • クエリ この句は省略可能であり、省略できます。QUERY This clause is optional and may be omitted.

  • input_statementinput_statement

    ステートメントを生成する結果セットは、次のいずれかになります。A result set producing statement and may be one of the following:

    • SELECTステートメントa SELECT statement
    • CTE(Common table expression)ステートメントa CTE(Common table expression) statement
    • INLINE TABLEステートメントan INLINE TABLE statement
    • TABLEステートメントa TABLE statement
    • FROMステートメント 'a FROM statement`

    クエリパラメーターの詳細な構文については、 「select ステートメント」 を参照してください。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|
+--------+---------+----------+