Informationen om din utdatafil bör anges mellan SELECT
och FROM
klausuler:
SELECT *
INTO OUTFILE "D:\Reports\Jan.csv"
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
FROM purchase
WHERE purchase.PO_DATE >= '1-1-2016'
MySQL 5.7 Referensmanual | LADDA DATAINFIL Syntax