通过出生年月查询平均年龄
SELECT
avg(
YEAR (
from_days(
datediff( now(), birthday ))))
FROM
table_name
WHERE
...
case when 语法查询分类信息
SELECT
name,
CASE
area
WHEN 1 THEN
'吴江开发区'
WHEN 2 THEN
'汾湖高新区'
WHEN 3 THEN
'东太湖度假区'
ELSE '未知'
END as area_name,
sum( number )
FROM
table_name
WHERE
...
根据时间（日期）分组查询
存储的为时分秒，要按照天分组
SELECT
count(*) AS num,
date_format( created_at, '%Y-%m-%d' ) as day_str
FROM
table_name
WHERE
...
GROUP BY
date_format( created_at, '%Y-%m-%d' )
网友评论