題目連結
題目描述
從titles表擷取按照title進行分組,每組個數大于等于2,給出title以及對應的數目t。
CREATE TABLE IF NOT EXISTS "titles" (
`emp_no` int(11) NOT NULL,
`title` varchar(50) NOT NULL,
`from_date` date NOT NULL,
`to_date` date DEFAULT NULL);
輸出描述:
title | t |
---|---|
Assistant Engineer | 2 |
Engineer | 4 |
省略 | 省略 |
Staff | 3 |
思路:
沒啥, 按照 title 分組, 統計每個組的行數, 然後選擇行數大于2 的即可
SELECT title, COUNT(*) AS t
FROM titles
GROUP BY title
HAVING t>=2
;