数据清洗

操作：

• 一张表的数据插入到另一张表，可以这样写：

INSERT INTO 目标表(字段1, 字段2, ...) SELECT 字段1, 字段2, ... FROM 来源表 WHERE 条件;

• 批量更新一张表的某个字段到另一张表，那么 SQL 可以类似这样写：

# 写法一
UPDATE b AS tb 
SET create_time = (SELECT create_time FROM a AS ta WHERE tb.id = ta.id AND tb.name = ta.name)

# 写法二
UPDATE b AS tb, (SELECT create_time, name FROM a) AS ta 
SET tb.create_time = ta.create_time
WHERE tb.id = ta.id AND tb.name = ta.name;