标签：count cut date 问题 解决 span [1] sele append
1、批量更新表中某个字段，如果表比较大，每条记录都执行一条update，1s执行10条数据，10万条数据就要1W秒，3个多小时。
2、可以用case when 来实现，模板如下
UPDATE categories SET display_order = CASE id WHEN 1 THEN 3 WHEN 2 THEN 4 WHEN 3 THEN 5 END WHERE id IN (1,2,3);
ID 是条件字段，WHEN 相当于where，THEN 表示要更新的字段设置成的值。
如果有多个字段要更新，模板如下
UPDATE categories SET dingdan = CASE id WHEN 1 THEN 3 WHEN 2 THEN 4 WHEN 3 THEN 5 END, title = CASE id WHEN 1 THEN ‘New Title 1‘ WHEN 2 THEN ‘New Title 2‘ WHEN 3 THEN ‘New Title 3‘ END WHERE id IN (1,2,3)
手动串接字符太麻烦，可以用python，每串接2000条，执行一次sql，1分钟内解决问题：
sql = " SELECT `id`,c_id,SUM(`total_price` - `reduction`) AS price FROM `orders` WHERE STATUS IN (9,11) AND total_price >0 GROUP BY c_id HAVING price > 0 ORDER BY c_id" datas = bt.getData(sql) error = 0 count = 0 totalcount = 0 id = [] sql = "UPDATE customer SET consumption_amount = consumption_amount + CASE id " sqlwhen = "" sqlend = "END WHERE id in " sqllen = 2000 with open("sqlupdatenew.sql",‘w‘) as f: print(len(datas)) for data in datas: if count <= sqllen: sqlwhen += "WHEN " + str(data[1]) + " THEN " + str(data[2]) + " " count += 1 id.append(data[1]) if count == sqllen or totalcount == len(datas) -1: mysql = sql + sqlwhen + sqlend + str(tuple(id)) bt.executesql(mysql) temp = sql + sqlwhen + sqlend + str(tuple(id)) + ";\n" f.write(temp) print(totalcount) count = 0 sqlwhen = "" id.clear() totalcount += 1 bt.closemysql()
标签：count cut date 问题 解决 span [1] sele append
原文地址：https://www.cnblogs.com/kilometerwine/p/9857660.html
