GROUPING_ID

説明

GROUP BYクエリにおける行のグループ化レベルを計算します。GROUPING_ID関数は、指定された出力行に対してGROUP BYリストのどの列が集約されていないかを示す整数ビットマップを返します。GROUP BYが指定されている場合、SELECT リスト、HAVING句、またはORDER BY句で使用できます。

構文

GROUPING_ID(<column_expression> [, ...])

パラメータ

パラメータ	説明
<column_expression>	GROUP BY句のカラム式。

戻り値

指定されたカラムのグルーピングビットマップを表すBIGINT値を返します。

例

例A: グルーピングレベルの識別

SELECT
  department,
  CASE 
    WHEN GROUPING_ID(department, level) = 0 THEN level
    WHEN GROUPING_ID(department, level) = 1 THEN CONCAT('Total: ', department)
    WHEN GROUPING_ID(department, level) = 3 THEN 'Total: Company'
    ELSE 'Unknown'
  END AS `Job Title`,
  COUNT(uid) AS `Employee Count`
FROM employee 
GROUP BY ROLLUP(department, level)
ORDER BY GROUPING_ID(department, level) ASC;

期待される出力:

+--------------------+---------------------------+----------------+
| department         | Job Title                 | Employee Count |
+--------------------+---------------------------+----------------+
| Board of Directors | Senior                    |              2 |
| Technology         | Senior                    |              3 |
| Sales              | Senior                    |              1 |
| Sales              | Assistant                 |              2 |
| Sales              | Trainee                   |              1 |
| Marketing          | Senior                    |              1 |
| Marketing          | Trainee                   |              2 |
| Marketing          | Assistant                 |              1 |
| Board of Directors | Total: Board of Directors |              2 |
| Technology         | Total: Technology         |              3 |
| Sales              | Total: Sales              |              4 |
| Marketing          | Total: Marketing          |              4 |
| NULL               | Total: Company            |             13 |
+--------------------+---------------------------+----------------+

例B: GROUPING_IDを使用して結果セットをフィルタする

SELECT
  department,
  CASE 
    WHEN GROUPING_ID(department, level) = 0 THEN level
    WHEN GROUPING_ID(department, level) = 1 THEN CONCAT('Total: ', department)
    WHEN GROUPING_ID(department, level) = 3 THEN 'Total: Company'
    ELSE 'Unknown'
  END AS `Job Title`,
  COUNT(uid) AS `Count`
FROM employee 
GROUP BY ROLLUP(department, level)
HAVING `Job Title` = 'Senior';

期待される出力:

+--------------------+-----------+-------+
| department         | Job Title | Count |
+--------------------+-----------+-------+
| Board of Directors | Senior    |     2 |
| Technology         | Senior    |     3 |
| Sales              | Senior    |     1 |
| Marketing          | Senior    |     1 |
+--------------------+-----------+-------+