Question

下面的Oracle查询给出error_message和Serial_num是否存在任何不同的错误。

如果计数为零或没有Different error而不显示空白/空结果。我怎么能看到这样的输出？我尝试使用NVL(error_message,0)和COALESCE (Sum(total),0)，但未获得所需的输出。

预期输出：

1   Different Errors:       0

Oracle SQL查询：

SELECT 
  1 as Index_Num, 
  CONCAT('Different Errors:  ', error_message || '# ' || serial_num), 
  SUM(total) 
FROM ( 
  SELECT error_message, serial_num, COUNT(*) total 
  FROM Table1 
  WHERE error_message NOT LIKE '%INVALID%' 
  GROUP BY error_message, serial_num
) 
GROUP BY error_message, serial_num

Answer 1

为子查询创建UNION ALL，并将NOT EXISTS与CTE一起使用，以解决WITH cte AS ( SELECT error_message, serial_num, COUNT(*) total FROM Table1 WHERE error_message NOT LIKE '%INVALID%' GROUP BY error_message, serial_num ) SELECT 1 as Index_Num, CONCAT( 'Different Errors: ', list_agg(error_message || '# ' || serial_num) within group (order by error_message) ), SUM(total) FROM cte UNION ALL SELECT 1, 'Different Errors: ', 0 FROM dual WHERE NOT EXISTS (SELECT 1 FROM cte)不返回任何行的情况：

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Answer 2

这并不是您所要的，但可能会有用。您可以使用grouping sets轻松添加包含错误总数的行：

SELECT 1 as Index_Num, 
       ('Different Errors:  ' || error_message || '# ' || serial_num), 
       COUNT(*) as total 
FROM Table1 
WHERE error_message NOT LIKE '%INVALID%' 
GROUP BY GROUPING SETS ( (error_message, serial_num), () );

A，即使有错误，这也会产生摘要行。在我看来，您可能会发现这很有用。

Answer 3

D'哦！看来我花了太长时间。这是后代的另一个选择：

SELECT 
  1, 
  CONCAT(
    'Different Errors:  ', 
    CASE 
      WHEN src.error_message IS NULL THEN '' 
      ELSE src.error_message || ' # ' || src.serial_num 
    END
  ) Summary,
  COALESCE(src.total, 0) AS total
FROM dual -- Get a seed row (in case there are no rows in error table)
LEFT JOIN (
  SELECT error_message, serial_num, COUNT(*) total 
  FROM Table1 
  WHERE error_message NOT LIKE '%INVALID%' 
  GROUP BY error_message, serial_num
) src ON 0=0

SQL Fiddle

如果没有记录计数，则显示零-ORACLE SQL查询

3 个答案: