- 导出CSV
第一种方法是在sql语句里进行处理：
利用mysql语法：IFNULL(expr1,'') expr1为要查的属性。
第二种方法 JAVA set，get方法：
- 导入CSV:
LOAD DATA infile '/test.txt'
INTO TABLE moo
fields
terminated BY ","
lines terminated BY "\n"
IGNORE 1 LINES
(@vone, @vtwo, @vthree, @vfour, @vfive)
SET
one = nullif(@vone,''),
two = nullif(@vtwo,''),
three = nullif(@vthree,''),
four = nullif(@vfour,'')