mysql load data处理空字符串导入数据库默认变成0的情况

会发生这种情况，一定是字段为int或者float类型，它会把空字符串默认为0，varchar则会还是空字符串

解决办法一般为两个：第一个把所有空字符串替换为\N

import re

with open("F:\\factor_db\\test_new", 'a') as g:
    for line in open("F:\\factor_db\\test_old.txt", 'r'):
        b = list(set(re.findall('\t+', line)))
        b.sort(key = lambda i:len(i),reverse=True)
        line = line.replace('\t\n', '\t\\N\n')
        if max([len(i) for i in b])==1:
            g.write(line)
        else:
            for i in b:
                templen=len(i)
                line=line.replace(i, '\t\\N'*(templen-1)+'\t')
            g.write(line)

 test_old.txt是直接从mysql生成的文本，test_new是最后处理成新的文本，然后直接

load data infile 'F:/factor_db/test_new' into table t_stock_factor_barra fields terminated by '\t' lines terminated by '\r\n' ignore 1 lines

数据库直接就是null

推荐第二个：

load data infile 'F:/factor_db/barra_test' into table t_stock_factor_barra fields terminated by '\t' lines terminated by '\r\n' ignore 1 lines
(`full_insID`,`date`,@`beta`,@`book_to_price_ratio`,@`earnings_yield`,@`growth`,@`leverage`,@`liquidity`,@`momentum`,@`non_linear_size`,@`residual_volatil

ity`,@`size`)
set
`beta` = NULLif(@beta,''),
`book_to_price_ratio` = NULLif(@book_to_price_ratio,''),
`earnings_yield` = NULLif(@earnings_yield,''),
`growth` = NULLif(@growth,''),
`leverage` = NULLif(@leverage,''),
`liquidity` = NULLif(@liquidity,''),
`momentum` = NULLif(@momentum,''),
`non_linear_size` = NULLif(@non_linear_size,''),
`residual_volatility` = NULLif(@residual_volatility,''),
`size` = NULLif(@size,'')
;

F:/factor_db/barra_test是要导入的文档

(`full_insID`,`date`,@`beta`,@`book_to_price_ratio`,@`earnings_yield`,@`growth`,@`leverage`,@`liquidity`,@`momentum`,@`non_linear_size`,@`residual_volatil

ity`,@`size`)

是数据库表字段名称，一定要按顺序写

加@的就是判断有空字符串，直接存为null的，下面跟上`字段名` = NULLif(@字段名,'')这句话就能完成了