Question

我有以下查询：

SELECT first, last, title, email, org 
FROM people WHERE email <> "" 
INTO OUTFILE 'C:/testfile.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n'

哪个有效。我需要选择不同的电子邮件（我不希望同一封电子邮件中有多个条目）。

它会起作用吗？：

SELECT first, last, title, distinct(email), org 
FROM people WHERE email <> "" 
INTO OUTFILE 'C:/testfile.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n'

Answer 1

您使用的是哪个SQL平台/版本？通常，这将使用group by语句完成。类似的东西：

SELECT first, last, title, email, org 
FROM people 
GROUP BY Email
WHERE email <> ""
INTO OUTFILE 'C:/testfile.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n'

以上内容实际上适用于SQL的某些平台/版本，但“正确”（标准sql）方式如下（当然，如果其他字段对于同一电子邮件不同，则会得到未定义的结果）：

SELECT max(first), max(last), max(title), email, max(org) 
FROM people 
GROUP BY Email
WHERE email <> ""
INTO OUTFILE 'C:/testfile.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n'

多列输出中的不同列值（然后转换为CSV）

1 个答案: