合並兩個具有相同詞干但不同where子句的SQL語句

Question

請幫我組合以下兩條SQL語句：

SELECT Count(*) AS total_number_of_followups_scheduled
FROM PROMIS_LT; 

和 ：

SELECT Count(Status) AS number_followups_completed,  
FROM PROMIS_LT
WHERE (Status = "Completed");

這就是我所擁有的，但它不起作用：

SELECT COUNT(*) As total_number_followups_scheduled, 
COUNT(Status) 
FROM (SELECT 
CASE WHEN (Status = 'Completed' THEN 1 ELSE 0 END) As number_followups_completed FROM PROMIS_LT)
PROMIS_LT;

Answer 1

你可以移動case表達的第二個內count通話，並使用的事實， count （以及許多類似的聚合函數）跳過null S：

SELECT COUNT(*) AS total_number_of_followups_scheduled,
       COUNT(CASE status WHEN 'Completed' THEN 1 END) AS number_followups_completed
FROM   promis_lt