null与not null
![](https://images2017.cnblogs.com/blog/1252614/201801/1252614-20180116111318615-1016225818.png)
2.not null CREATE TABLE `test` ( `col1` VARCHAR( 10 ) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ) ENGINE = MYISAM ;
![](https://images2017.cnblogs.com/blog/1252614/201801/1252614-20180116111318615-1016225818.png)
2.not null CREATE TABLE `test` ( `col1` VARCHAR( 10 ) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ) ENGINE = MYISAM ;