常用SQL记录[随时更新]

分组统计，时间维度、类目维度，分组后排序

-- 统计条数
SELECT pubdate_day AS 日期, level_1 AS 一级品类, count(article_id) AS 发布数
FROM t1
WHERE pubdate_day > '20190801'
  AND pubdate_day < '20190901'
GROUP BY 日期, 一级品类
ORDER BY 日期, 发布数 DESC;


-- 求平均值
SELECT DATE_FORMAT(dt, '%Y%m') AS 月份,
       level_1                 AS '品类',
       AVG(app_pv)             AS '品类月均PV'
FROM t2
WHERE dt > '20191001'and dt < '20200101'
GROUP BY level_1,
         月份
ORDER BY 月份 DESC

修改列名称

ALTER TABLE
  t1 CHANGE COLUMN c1 c2 VARCHAR(255) COMMENT  '本列的注释'