ORDER BY Alias not working

问题

UPDATING QUESTION:

ERROR:  column "Fruits" does not exist

Running Postgres 7.4(Yeah we are upgrading)

Why can't I ORDER BY the column alias? wants tof."TypeOfFruits" in the ORDER BY as well, why?

SELECT (CASE
    WHEN tof."TypeOfFruits" = 'A' THEN 'Apple' 
    WHEN tof."TypeOfFruits" = 'P' THEN 'Pear' 
    WHEN tof."TypeOfFruits" = 'G' THEN 'Grapes' 
    ELSE 'Other' END) AS "Fruits",
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('DAY', LOCALTIMESTAMP) AND DATE_TRUNC('DAY', LOCALTIMESTAMP) + INTERVAL '1 DAY' 
        THEN 1 ELSE 0 END) AS daily, 
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('MONTH', LOCALTIMESTAMP) AND DATE_TRUNC('MONTH', LOCALTIMESTAMP) + INTERVAL '1 MONTH' 
        THEN 1 ELSE 0 END) AS monthly, 
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('YEAR', LOCALTIMESTAMP) AND DATE_TRUNC('YEAR', LOCALTIMESTAMP) + INTERVAL '1 YEAR' 
        THEN 1 ELSE 0 END) AS yearly, 
    SUM(CASE WHEN r.order_date >= '01-01-2011 00:00:00' THEN 1 ELSE 0 END) AS lifetime 
FROM reports AS r, "TypeOfFruits" AS tof 
WHERE r.id = tof."ID" 
GROUP BY "Fruits"
ORDER BY CASE 
    WHEN "Fruits" = 'Apple' THEN 1 
    WHEN "Fruits" = 'Pear' THEN 2 
    WHEN "Fruits" = 'Grapes' THEN 3 
    ELSE 4 
END

Results as of now

Fruits;daily;monthly;yearly;lifetime
"Apple";17;1174;3136;3136
"Pear";28;94;94;94
"Grapes";0;191;490;490
"Other";0;2;27;27
"Other";0;0;1;1
"Other";0;0;27;27
"Other";0;6;28;28
"Other";0;58;229;229
"Other";0;3;3;3
"Other";0;0;1;1

Desired results would be one row with the "Other" total, so four rows altogether (x would be the total)

Fruits;daily;monthly;yearly;lifetime
"Apple";17;1174;3136;3136
"Pear";28;94;94;94
"Grapes";0;191;490;490
"Other";x;x;x;x

回答1:

You can use ORDER BY 1 to order by the first field, which is "Fruits". The same is valid for GROUP BY

Update

For the order, instead of doing the case in the order by, create a new column in.. say.. the second position:

(CASE 
    WHEN "Fruits" = 'Apple' THEN 1 
    WHEN "Fruits" = 'Pear' THEN 2 
    WHEN "Fruits" = 'Grapes' THEN 3 
    ELSE 4 ) as Order

Then in you ORDER BY 2.

回答2:

The reason for this can be found in the documentation:

Each expression [in the ORDER BY list] can be the name or ordinal number of an output column (SELECT list item), or it can be an arbitrary expression formed from input-column values.

(my emphasis)

The reason for this is that old versions of the SQL standard (SQL-92) only allowed sorting by output column name or number, whereas newer versions allow sorting by arbitrary expressions, but those expressions are formed from input column values.

Other answers already contain various suitable workarounds for your case.

回答3:

The alias is assigned after the order by so you can't use it in the order by. Use this instead:

(CASE
    WHEN tof."TypeOfFruits" = 'A' THEN 'Apple' 
    WHEN tof."TypeOfFruits" = 'P' THEN 'Pear' 
    WHEN tof."TypeOfFruits" = 'G' THEN 'Grapes' 
    ELSE 'Other' END)

回答4:

Consider something like this:

SELECT * FROM (SELECT (CASE
    WHEN tof."TypeOfFruits" = 'A' THEN 'Apple' 
    WHEN tof."TypeOfFruits" = 'P' THEN 'Pear' 
    WHEN tof."TypeOfFruits" = 'G' THEN 'Grapes' 
    ELSE 'Other' END) AS "Fruits", 
    (CASE 
    WHEN tof."TypeOfFruits" = 'A' THEN 1 
    WHEN tof."TypeOfFruits" = 'P' THEN 2 
    WHEN tof."TypeOfFruits" = 'G' THEN 3 
    ELSE 4 END) as NUM

        FROM ..... <rest of your query without group by and order by .....
    )

GROUP BY Fruits
ORDER BY NUM

回答5:

You could try something like this ... untested, but I've seen similar queries.
Let me know if it works...

SELECT "Fruits",
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('DAY', LOCALTIMESTAMP) AND DATE_TRUNC('DAY', LOCALTIMESTAMP) + INTERVAL '1 DAY' 
        THEN 1 ELSE 0 END) AS daily, 
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('MONTH', LOCALTIMESTAMP) AND DATE_TRUNC('MONTH', LOCALTIMESTAMP) + INTERVAL '1 MONTH' 
        THEN 1 ELSE 0 END) AS monthly, 
    SUM(CASE WHEN r.order_date 
        BETWEEN DATE_TRUNC('YEAR', LOCALTIMESTAMP) AND DATE_TRUNC('YEAR', LOCALTIMESTAMP) + INTERVAL '1 YEAR' 
        THEN 1 ELSE 0 END) AS yearly, 
    SUM(CASE WHEN r.order_date >= '01-01-2011 00:00:00' THEN 1 ELSE 0 END) AS lifetime 
FROM reports AS r
    ,(SELECT "ID",
             CASE
                WHEN tof."TypeOfFruits" = 'A' THEN 'Apple' 
                WHEN tof."TypeOfFruits" = 'P' THEN 'Pear' 
                WHEN tof."TypeOfFruits" = 'G' THEN 'Grapes' 
                ELSE 'Other'
             END AS "Fruits" FROM "TypeOfFruits" ) AS "tof"
WHERE r.id = tof."ID" 
GROUP BY "Fruits"
ORDER BY CASE 
    WHEN "Fruits" = 'Apple' THEN 1 
    WHEN "Fruits" = 'Pear' THEN 2 
    WHEN "Fruits" = 'Grapes' THEN 3 
    ELSE 4 
END

回答6:

Try using backticks (`) instead of single/double quotes to wrap your alias name.

Had the same issue with MySQL; backticks fixed the problem.

来源：https://stackoverflow.com/questions/6458669/order-by-alias-not-working

标签

sql

postgresql

group-by

aggregate-functions