1、错误描述

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxError Exception：You have an error in your SQL syntax check the manual that corresponds to your MySQL server version for the right syntax to use near 'notnull,user_name
varchar(255) )' at line 1

2、错误原因

StringBuilder sql = new StringBuilder();
sql.append("create table t_you_su_ta(");
sql.append(" id int primary key,");
sql.append(" user_id int notnull,");
sql.append(" user_name varchar(255))");

在拼接创建数据库表时，要使user_id不为空，定义成了“notnull”

3、解决办法

在拼接user_id时，应改成“user_id int not null”