请教各位,这句SQL语句是什么意思,作用是干嘛的?

Question

SELECT T0."_ID",T0."ALBUMID",T0."PHOTOID" , T."_ID",T."SYSID",T."FILENAME",T."FILEPATH",T."FILESIZE",T."FILETYPE",T."MODIFIEDTIME",T."SHOOTTIME",T."WIDTH",T."HEIGHT",T."LONGITUDE",T."LATITUDE",T."DURATION",T."ENCRYPTPATH",T."ISMOVED",T."CITY" FROM CLASSIFIES_PHOTO T0 LEFT JOIN PHOTO T ON T."_ID"=T0."PHOTOID"

Answer 1

 SELECT
    T0."_ID",
    T0."ALBUMID",
    T0."PHOTOID",
    T."_ID",
    T."SYSID",
    T."FILENAME",
    T."FILEPATH",
    T."FILESIZE",
    T."FILETYPE",
    T."MODIFIEDTIME",
    T."SHOOTTIME",
    T."WIDTH",
    T."HEIGHT",
    T."LONGITUDE",
    T."LATITUDE",
    T."DURATION",
    T."ENCRYPTPATH",
    T."ISMOVED",
    T."CITY"
FROM
    CLASSIFIES_PHOTO T0
LEFT JOIN PHOTO T ON T."_ID" = T0."PHOTOID"

这样不是看的很清楚吗？ 这不就是一条查询语句吗？ 左连接 返回左边的结果集，并根据ON后面条件返回右边结果集 PHOTO