问题
I have three queries with results.
Query 1:
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 1 AND workid < 557 AND workid > 188
GROUP BY employeeid, clientid ORDER BY clientid ASC;
employeeid | clientid | under_over_1
------------+----------+--------------
1 | 3 | 0.54
1 | 4 | 0.47
1 | 6 | 0.45
1 | 7 | 0.59
. | . | .
. | . | .
Query 2:
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1.31666666666667, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 2
GROUP BY employeeid, clientid ORDER BY clientid ASC;
employeeid | clientid | under_over_1
------------+----------+--------------
2 | 2 | 1.01
2 | 3 | 0.21
2 | 4 | 0.71
2 | 6 | 0.68
. | . | .
. | . | .
Query: 3
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1.31666666666667, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 3
GROUP BY employeeid, clientid ORDER BY clientid ASC;
employeeid | clientid | under_over_1
------------+----------+--------------
3 | 4 | 0.70
3 | 6 | 0.54
3 | 7 | 1.03
3 | 11 | 0.74
. | . | .
. | . | .
I want to output one table with the result of all three queries such as (I am sorry but I have to write more here so I can submit this post. I hope this is enough;-)):
employeeid | clientid | under_over_1
------------+----------+--------------
1 | 3 | 0.54
1 | 4 | 0.47
1 | 6 | 0.45
1 | 7 | 0.59
. | . | .
. | . | .
2 | 2 | 1.01
2 | 3 | 0.21
2 | 4 | 0.71
2 | 6 | 0.68
. | . | .
. | . | .
3 | 4 | 0.70
3 | 6 | 0.54
3 | 7 | 1.03
3 | 11 | 0.74
. | . | .
. | . | .
I tried UNION ALL as in
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 1 AND workid < 557 AND workid > 188
GROUP BY employeeid, clientid ORDER BY clientid ASC
UNION ALL
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1.31666666666667, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 3
GROUP BY employeeid, clientid ORDER BY clientid ASC
UNION ALL
SELECT DISTINCT employeeid, work.clientid, ROUND ((CAST (AVG(current_lawn_price) AS numeric) / CAST (AVG((((EXTRACT(HOUR FROM job_finish)*60) + EXTRACT(MIN FROM job_finish))) - ((EXTRACT(HOUR FROM job_start)*60) + EXTRACT(MIN FROM job_start))) AS numeric)) / 1.31666666666667, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 2
GROUP BY employeeid, clientid ORDER BY clientid ASC;
However, I get the following error:
ERROR: syntax error at or near "UNION" LINE 7: UNION ALL
I am not sure why this is wrong or whether UNION ALL is the right approach here. Anyone have a clue?
回答1:
The immediate cause for the error is, quoting the manual:
(
ORDER BYandLIMITcan be attached to a subexpression if it is enclosed in parentheses. Without parentheses, these clauses will be taken to apply to the result of theUNION, not to its right-hand input expression.)
Bold emphasis mine.
So, as suggested by @wilx, enclosing each SELECT in parentheses would fix that.
But there is more.
Merge into single query
SELECT employeeid, work.clientid -- no DISTINCT
, ROUND ((AVG(current_lawn_price)
/ AVG(extract(epoch FROM job_finish - job_start)))::numeric / 79, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE (employeeid IN (1, 2) OR
employeeid = 3
AND workid < 557
AND workid > 188)
GROUP BY employeeid, clientid
ORDER BY CASE employeeid
WHEN 1 THEN 1
WHEN 2 THEN 3
WHEN 3 THEN 2
END
, clientid;
Merge the 3 SELECT queries.
Remove the redundant DISTINCT. That's an expensive no-op after GROUP BY.
Instead of extracting hours and minutes from both begin and end timestamps etc., compute the interval by plain subtraction (works with timestamp or time values alike) and extract the epoch from it. Gives you the number of seconds. Divide by 60 and you got the number of minutes much faster. 79 being the result of 60 * 1.31666666666667, accordingly.
The manual about extracting epoch:
For
timestamp with time zonevalues, the number of seconds since 1970-01-01 00:00:00 UTC (can be negative); fordateandtimestampvalues, the number of seconds since 1970-01-01 00:00:00 local time; forintervalvalues, the total number of seconds in the interval
Bold emphasis mine.
Since this removes UNION ALL, the parentheses mentioned at the top are not needed any more.
The CASE expression makes up for the mixed order in employeeid, like sticky bit provided.
If queries cannot be merged
If, for some reason, you can't or won't merge the three original SELECT queries, do this instead:
( -- parentheses required
SELECT employeeid, work.clientid -- no DISTINCT !
, ROUND ((AVG(current_lawn_price)
/ AVG(extract(epoch FROM job_finish - job_start)))::numeric / 79, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 1
AND workid < 557
AND workid > 188
GROUP BY clientid -- no need to GROUP BY employeeid while filtering single value
ORDER BY clientid
)
UNION ALL
(
SELECT employeeid, work.clientid
, ROUND ((AVG(current_lawn_price)
/ AVG(extract(epoch FROM job_finish - job_start)))::numeric / 79, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 3
GROUP BY clientid
ORDER BY clientid
)
UNION ALL
(
SELECT employeeid, work.clientid
, ROUND ((AVG(current_lawn_price)
/ AVG(extract(epoch FROM job_finish - job_start)))::numeric / 79, 2) AS under_over_1
FROM work
JOIN timesheet USING (date_linkid)
JOIN client USING (clientid)
WHERE employeeid = 2
GROUP BY clientid
ORDER BY clientid
);
-- no outer ORDER BY required
Keep ORDER BY per SELECT and add parentheses to fix the syntax. UNION ALL (as opposed to UNION) simply appends results preserving the order of individual SELECTs. This should be cheaper than ordering the whole set after UNION ALL. And you did want to keep using queries individual SELECT queries "as is" ...
Most of the other advice above applies accordingly.
Aside: make it a habit to use table aliases and table-qualify all columns in queries joining multiple tables. Much more robust against later changes and easier to read / debug.
回答2:
Remove all the ORDER BYs. Then use the resulting query as a derived table. To retain the order you presumably want, you can then use a CASE expression to map the employeeid to and integer determining the order:
SELECT x.employeeid,
x.clientid,
x.under_over_1
FROM (<your UNION ALL query without the ORDER BYs>) x
ORDER BY CASE x.employeeid
WHEN 1 THEN
1
WHEN 2 THEN
3
WHEN 3 THEN
2
END,
x.clientid;
来源：https://stackoverflow.com/questions/59348755/combining-3-select-statements-to-output-1-table