I have a table of user preferences - 'pr_gantt_config' and a table of default values for all the configurable elements of the chart - 'pr_gantt'. I was hoping this query would return either the user expressed the preference or the default value from pr_gantt for all configurable values but I only get the rows where the user has expressed preference. I know I could store a value for each user against each value, but that feels inefficient.
SELECT `code`,
`pref`,
`type`,
Ifnull(`pref`, `pr_gantt`.`default_value`) AS `pref`
FROM `pr_gantt_config`
LEFT JOIN `pr_gantt`
ON ( `pr_gantt_config`.`gantt_id` = `pr_gantt`.`id` )
WHERE `pr_gantt_config`.`user_id` = '1'
Your help greatly appreciated.
A work arround would be to first create a view of both tables.
CREATE VIEW temp AS
SELECT code, pref, type,pref, pr_gantt.default_value FROM pr_gantt_config
LEFT JOIN pr_gantt ON (pr_gantt_config.gantt_id = pr_gantt.id) WHERE
pr_gantt_config.user_id = '1'
and then select with IFNULL
SELECT code,type, IFNULL(pref, pr_grannt.default_value) FROM temp
Related
I would like to add to the table A all the column of the table B, doing a join based on a common column (type numeric). I am trying to do it using the LEFT JOIN but the columns added are all blank. this is impossible because table b stores, among others, the same ID values . Where I am wrong?
Select * from "2017_01" left join "Registry_2017" on '2017_01.ID' = 'Registry_2017.ID';
You are doing wrong.. I don't know why you can use right for Table calling "2017_01" and different with this '2017_01.ID'..
' = Single quote identifies as String
" = Double quote identifies as Table or Column to escape Naming
Select
*
From
"2017_01"
left join "Registry_2017" on '2017_01.ID' = 'Registry_2017.ID';
So when you doing this '2017_01.ID' = 'Registry_2017.ID' The condition will always become false because those 2 different String are not equal. Postgresql look the condition not as Table and Column but String because you are using Single quote
Select
*
from
"2017_01"
left join "Registry_2017" on "2017_01"."ID" = "Registry_2017"."ID";
So the query should be like that.. Even you already got answer and it got work i must tell this..
I'm trying to decipher another programmer's code who is long-gone, and I came across a select statement in a stored procedure that looks like this (simplified) example:
SELECT #Table2.Col1, Table2.Col2, Table2.Col3, MysteryColumn = CASE WHEN y.Col3 IS NOT NULL THEN #Table2.MysteryColumn - y.Col3 ELSE #Table2.MysteryColumn END
INTO #Table1
FROM #Table2
LEFT OUTER JOIN (
SELECT Table3.Col1, Table3.Col2, Col3 = SUM(#Table3.Col3)
FROM Table3
INNER JOIN #Table4 ON Table4.Col1 = Table3.Col1 AND Table4.Col2 = Table3.Col2
GROUP BY Table3.Col1, Table3.Col2
) AS y ON #Table2.Col1 = y.Col1 AND #Table2.Col2 = y.Col2
WHERE #Table2.Col2 < #EnteredValue
My question, what does the fourth column of the primary selection do? does it produce a boolean value checking to see if the values are equal? or does it set the #Table2.MysteryColumn equal to some value and then inserts it into #Table1? Or does it just update the #Table2.MysteryColumn and not output a value into #Table1?
This same thing seems to happen inside of the sub-query on the third column, and I am equally at a loss as to what that does as well.
MysteryColumn = gives the expression a name also called a column alias. The fact that a column in the table#2 also has the same name is besides the point.
Since it uses INTO syntax it also gives the column its name in the resulting temporary table. See the SELECT CLAUSE and note | column_alias = expression and the INTO CLAUSE
I just created a temporary table as:
create temporary table userAndProductSales as
select p.p_name, u.u_name, u.s_price, u.quantity
from product p
join userAndStates u
on p.s_id = u.s_id
Now I want to select some columns with a particular order. For example, I want the select to give me an output of:
u_name1 p_name1
u_name1 p_name2
u_name1 p_name3
u_name1 p_name4
...
u_name2 p_name1
u_name2 p_name2
u_name2 p_name3
....
and so on and so forth. How do I get this ouput? I've tried something on the lines of:
select (select u_name from userandproductsales order by u_name), p_name from userandproductsales
but I'm getting an error
UPDATE: Figured out that the table I'm joining isn't giving me the correct data I want. Thanks for the help though.
Here is how to use ORDER BY :
SELECT * from userandstatesales
order by u_name , p_name
Unless there is a reason for creating a temporary table (like needing to access it later in the same session), you should avoid the expense and simply do a order by from your select. For example:
select p.p_name, u.u_name, u.s_price, u.quantity
from product p
join userAndStates u
on p.s_id = u.s_id
order by u.u_name, p.p_name;
In my application i have a query that do multiple joins with a table position. Just like this:
SELECT *
FROM (...) as trips
join trip as t on trips.trip_id = t.trip_id
left outer join vehicle as v on v.vehicle_id = t.trip_vehicle_id
left outer join position as start on trips.start_position_id = start.position_id and start.position_vehicle_id = v.vehicle_id
left outer join position as "end" on trips.end_position_id = "end".position_id and "end".position_vehicle_id = v.vehicle_id
left outer join position as last on trips.last_position_id = last.position_id and last.position_vehicle_id = v.vehicle_id;
My table position has 35 columns(for example position_id).
When I run the query, in result should appear the table position 3 times, start, end and last. But postgres can not distinguish between, for exemplar, start.position_id, end.position_id and last.position_id. So this 3 columns are group and appear as one, position_id.
As the data from start.position_id and end.position_id are different, the column, position_id, that appear in result, it's empty.
Without having to rename all the columns, like this: start.position_id as start_position_id.
How can i get each group of data separately, for exemple, get all columns from the table 'start'. In MYSQL i can do this operation by calling fetch_fields, and give the function an alias, like 'start'.
But i can i do this in Postgres?
Best Regards,
Nuno Oliveira
My understanding is that you can't (or find it difficult to) discern between which table each column with a shared name (such as "position_id") belongs to, but only need to see one of the sets of shared columns at any one time. If that is the case, use tablename.* in your SELECT, so SELECT trips.*, start.*... would show the columns from trips and start, but no columns from other tables involved in the join.
SELECT [...,] start.* [,...] FROM [...] atable AS start [...]
I have a lengthy query here, and wondering whether it could be refactor?
Declare #A1 as int
Declare #A2 as int
...
Declare #A50 as int
SET #A1 =(Select id from table where code='ABC1')
SET #A2 =(Select id from table where code='ABC2')
...
SET #A50 =(Select id from table where code='ABC50')
Insert into tableB
Select
Case when #A1='somevalue' Then 'x' else 'y' End,
Case when #A2='somevalue' Then 'x' else 'y' End,
..
Case when #A50='somevalue' Then 'x' else 'y' End
From tableC inner join ......
So as you can see from above, there is quite some redundant code. But I can not think of a way to make it simpler.
Any help is appreciated.
If you need the variables assigned, you could pivot your table...
SELECT *
FROM
(
SELECT Code, Id
FROM Table
) t
PIVOT
(MAX(Id) FOR Code IN ([ABC1],[ABC2],[ABC3],[ABC50])) p /* List them all here */
;
...and then assign them accordingly.
SELECT #A1 = [ABC1], #A2 = [ABC2]
FROM
(
SELECT Code, Id
FROM Table
) t
PIVOT
(MAX(Id) FOR Code IN ([ABC1],[ABC2],[ABC3],[ABC50])) p /* List them all here */
;
But I doubt you actually need to assign them at all. I just can't really picture what you're trying to achieve.
Pivotting may help you, as you can still use the CASE statements.
Rob
Without taking the time to develop a full answer, I would start by trying:
select id from table where code in ('ABC1', ... ,'ABC50')
then pivot that, to get one row result set of columns ABC1 through ABC50 with ID values.
Join that row in the FROM.
If 'somevalue', 'x' and 'y' are constant for all fifty expressions. Then start from:
select case id when 'somevalue' then 'x' else 'y' end as XY
from table
where code in ('ABC1', ... ,'ABC50')
I am not entirely sure from your example, but it looks like you should be able to do one of a few things.
Create a nice look up table that will tell you for a given value of the select statement what should be placed there. This would be much shorter and should be insanely fast.
Create a simple for loop in your code and generate a list of 50 small queries.
Use sub-selects or generate a list of selects with one round trip to retrieve your #a1-#A50 values and then generate the query with them already in place.
Jacob