Tag:mysqlnotnull

  • Solution to the problem that not in is null in MySQL

    Time:2020-8-11

    Some time ago, when I was doing a small function in the company, I counted the number of data in a certain situation and then modified the problem. At that time, I thought it was very simple. I wrote the following SQL: SELECT COUNT(*) FROM t1 where tl.c1 not IN (SELECT t2.c1 FROM t2); The […]