如何使用 case when 语句在列中设置 Mysql 加载的 table 项目

Question

我所在的csv文件中的一列有3个字母：c、e和n。当我导入数据时，我希望它们分别变为 2、1 和 0。当我在SET语句中使用运行 CASE WHEN时，table每行只有returns 2个。我在这里做错了什么？

load data local infile 'C:\Scripts\Storagefile.csv'
into table  infra.storage
fields terminated by ','
enclosed by '"'
lines terminated by '\r\n'
ignore 1 rows

(status, gasday, gasinstorage, percent_full, net_change, injection, withdrawal, workingstorage, injection_cap, withdrawal_cap, @dummy)

set 
status = (SELECT case
        when status = 'C' then 2
        when status = 'E' then 1
        when status = 'N' then 0 end),  
entity = 'EU',
gasinstorage = gasinstorage * 3.142142,
net_change =  net_change * 3.142142,
injection = injection  * 3.142142,
withdrawal = withdrawal * 3.142142,
workingstorage = workingstorage * 3.142142,
injection_cap = injection_cap  * 3.142142,
withdrawal_cap = withdrawal_cap * 3.142142,
reportdate = current_timestamp()

Answer 1

这里有一个 sql 的解决方案。要preprocess the input，需要先将CSV值赋给一个变量，然后使用set子句。

这应该接近你想要的：

load data local infile 'C:\Scripts\Storagefile.csv'
into table infra.storage (
    @status, 
    gasday, 
    @gasinstorage, 
    percent_full, 
    @net_change, 
    @injection, 
    @withdrawal, 
    @workingstorage, 
    @injection_cap, 
    @withdrawal_cap, 
    @dummy
)
fields terminated by ','
enclosed by '"'
lines terminated by '\r\n'
ignore 1 rows
set 
    status = case @status
        when 'C' then 2
        when 'E' then 1
        when 'N' then 0
    end,
    entity = 'EU',          
    gasinstorage = @gasinstorage * 3.142142,
    net_change =  @net_change * 3.142142,
    injection = @injection  * 3.142142,
    withdrawal = @withdrawal * 3.142142,
    workingstorage = @workingstorage * 3.142142,
    injection_cap = @injection_cap  * 3.142142,
    withdrawal_cap = @withdrawal_cap * 3.142142,
    reportdate = current_timestamp()
;

如何使用 case when 语句在列中设置 Mysql 加载的 table 项目

How can I set Mysql loaded table items in a column using a case when statement

mysql

sql

csv

sql-insert

load-data-infile