Daily learning 3

1.SQL Sentence Niuke brush questions

1.

Last question yesterday , My method seems to go against the original intention of the author , Because the topic is subquery , And the method I use is linked table query , So I did it again with subquery in a few days , Subquery is to use in（） Create another query in parentheses , Result set as in Comparison set of previous elements . 

（ Subquery and self connection are not the same thing ！）

2.

This problem is to redo the right connection of division .  It is mainly about the flexible use of left-right connections and internal connections .

3.

  This problem is to clarify the relationship between the tables , Today, after the system learned the linked table query , The use of external connections is more clearly understood . 

2. Force button brush questions

3.JavaWeb Study

I finished learning as planned yesterday css part , today Start Study Javascript.

4. Study MySQL

Watch the video learning to see the sub query

see 《MySQL Must learn knowledge 》 See Chapter 8

  Here are some important content interceptions