mysql5.7 base select...where...is NOT NULL to find content that is not null

Li Wu:
Heng Learn to think together, honouring teachers save Thanksgiving. Leaf See root three return to one, rivers the same oneness.
Meekness Conscience Lord, willing to do without regrets to the most bitter. Reading exercises to keep the body and mind, sincere advice and the line and cherish.

Data,

data, Lingen on the data. You must be cautious about operating the database. Give the most bitter code here, and take a look at it, to have your own judgment.  Meet the choice, or ashamed to ask.

mysql:5.7
Os:windows7 x64

Code and effects

Mysql> SELECT * FROM t1;+------+-------+| ID   | name  |+------+-------+|    4 | Hello | |    2 | World | | NULL | Nihao | |    3 | Nihao | |  100 | Nihao |+------+-------+5 rows in Set (0.00 sec) mysql> SELECT * from t1 where ID was not null;+------+-------+| ID   | name  |+------+-------+|    4 | Hello | |    2 | World | |    3 | Nihao | |  100 | Nihao |+------+-------+4 rows in Set (0.00 sec) mysql>

MySQL, relational database management system, excellent, worth learning.
Learning resources: Itcast and Itheima video library + Pure Heart.
If you have public resources, can share to me, with your resources to learn also can.
Blog post is to watch the video, into thinking written. It's good that the teacher speaks well. Blog bad, is to give the most bitter not serious.

mysql5.7 base select...where...is NOT NULL to find content that is not null