can't create/write to file '/tmp/#sql_23e6_0MYI'

解决方法：
              mkdir /var/lib/mysql/tmp
              //分配tmp读写权限
              chown  mysql:mysql /var/lib/mysql/tmp 或（chown -R mysql.mysql 文件名）
              vi /etc/my.cnf
              tmpdir = /var/lib/mysql/tmp
              service mysqd restart