分組是由null還是不是？

Question

我想統計Firebird數據庫中有多少條記錄的時間戳字段爲空或不爲空。怎麼做？

事情是這樣的：

select RECORD_TYPE, count(*), (MY_TIMESTAMP IS NULL) from MY_TABLE 
group by RECORD_TYPE, (MY_TIMESTAMP IS NULL) 

我用火鳥2.5

Answer 1

可以輸出具有兩列的單個記錄，

SELECT COUNT(MY_TIMESTAMP) AS TOTAL_NOTNULL, 
     COUNT(CASE WHEN MY_TIMESTAMP IS NULL THEN 1 END) TOTAL_NULL 
FROM MY_TABLE