的BigQuery不允許子選擇在SELECT子句

Question

我有樣有2臺：

table POINT_STATUS: 
rank_point status 
9  excellent 
5  good 
3  bad 
0  fail 

table STUDENT_POINT: 
student  point 
student A 8 
student B 9 
student C 5 
student D 4 

如何在創建的BigQuery查詢學生(with point >= rank_point)獲取狀態？

注意： - BigQuery不允許子選擇在select子句中。

Answer 1

注意：BigQuery不允許子選擇在select子句中。

它DOES支持使用標準SQL - 見Enabling Standard SQL

WITH POINT_STATUS AS (
    SELECT 9 AS rank_point, 'excellent' AS status UNION ALL 
    SELECT 5 AS rank_point, 'good' AS status UNION ALL 
    SELECT 3 AS rank_point, 'bad' AS status UNION ALL 
    SELECT 0 AS rank_point, 'fail' AS status 
), 
STUDENT_POINT AS (
    SELECT 'student A' AS student, 8 AS point UNION ALL 
    SELECT 'student B' AS student, 9 AS point UNION ALL 
    SELECT 'student C' AS student, 5 AS point UNION ALL 
    SELECT 'student D' AS student, 4 AS point 
) 
SELECT 
    student, point, 
    (SELECT status 
    FROM POINT_STATUS 
    WHERE rank_point <= point 
    ORDER BY rank_point DESC 
    LIMIT 1 
) AS status 
FROM STUDENT_POINT 

同時，如果您綁定到傳統的SQL，請參見下面

SELECT student, point, status FROM (
    SELECT 
    student, point, status, 
    ROW_NUMBER() OVER(PARTITION BY student ORDER BY rank_point DESC) AS pos 
    FROM STUDENT_POINT 
    CROSS JOIN POINT_STATUS 
    WHERE point - rank_point >= 0 
) 
WHERE pos = 1