how can I create a table based on the output of previous queries? I tried Create table as select distinct syntax but it doesn't work.
ps: the previous queries contain inner join SET dateformat dmy
select distinct c.peril, c.period, c.eventid, c.eventdate, c.loss_index_2016,
c.loss_index_20182019, a.eventdatetime, b.region, a.year,a.eventid
from RetroNCTJan2019v5 a
inner join retropltheader2019v5 b
on a.segmentid=b.segmentid
inner join Index2019 c
on b.region = c.peril and a.Year = c.period and
a.eventid=convert(numeric(30,0),convert(float(28),c.eventid)) and
month(eventdate) = month(eventdatetime) and day(eventdate)=day(eventdatetime)
In SQL Server you insert the results of a SELECT into a new table using INTO:
select distinct c.peril, c.period, c.eventid,c.eventdate, c.loss_index_2016, c.loss_index_20182019,
a.eventdatetime, b.region, a.year,a.eventid
into new_table
from RetroNCTJan2019v5 a join
retropltheader2019v5 b
on a.segmentid = b.segmentid join
Index2019 c
on b.region = c.peril and a.Year = c.period and
a.eventid = convert(numeric(30,0), convert(float(28),c.eventid)) and
month(eventdate) = month(eventdatetime) and
day(eventdate) = day(eventdatetime)
Most databases use create table as, which in my opinion, is a little clearer.
That said, you should learn some better coding habits:
Use table aliases that are meaningful. This usually means abbreviations of the table names. Don't use arbitrary letters.
Qualify all column references, especially when your query has more than one table reference.
Converting to a float and then a numeric is probably unnecessary. In fact, having to do a type conversion in a JOIN condition is suspicious -- and even more so when the two columns have the same name. Same name --> same type.
Related
This is the code example
for three tables and I made a link on them
Now I want to add the age column from table D
SELECT A.COD,a.namee, B.NAMEE,C.NAMEE
FROM ((A INNER JOIN B ON A.COD = B.COD)
LEFT JOIN C ON A.COD = C.COD)
I mean, this code is expected
SELECT A.COD, a.name , B.NAME,C.NAME ,D.Age
FROM ((A INNER JOIN B ON A.COD = B.COD)
LEFT JOIN C ON A.COD = C.COD) , D
But in access, an error message appears, the text of the message says that the JOIN method is not supported
Is there a way to solve this?
Access does not allow to do a direct cross-join (operator ",") involving an SQL expression that includes a different type of join. The solution is as simple as enclosing the first operation between parentheses and add another SELECT, as follows:
SELECT T_A.COD, T_A.Name_ , T_B.Name_, T_C.Name_, T_D.Age
FROM
(
SELECT T_A.COD, T_A.Name_ , T_B.Name_, T_C.Name_
FROM
( T_A
INNER JOIN
T_B
ON T_A.COD = T_B.COD)
LEFT JOIN
T_C
ON T_A.COD = T_C.COD
)
, T_D
My advice is that you always enclose in a SELECT every individual join operation (with the exception of cross-joins) as good programming practice. There is no problem in doing a series of cross-joins because the cross-join operator is associative.
I have a flag in a table which value ( 1 for US, or 2 for Global) indicates if the data will be in Table A or Table B.
A solution that works is to left join both tables; however this slows down significantly the scripts (from less than a second to over 15 seconds).
Is there any other clever way to do this? an equivalent of
join TableA only if TableCore.CountryFlag = "US"
join TableB only if TableCore.CountryFlag = "global"
Thanks a lot for the help.
You can try using this approach:
-- US data
SELECT
YourColumns
FROM
TableCore
INNER JOIN TableA AS T ON TableCore.JoinColumn = T.JoinColumn
WHERE
TableCore.CountryFlag = 'US'
UNION ALL
-- Non-US Data
SELECT
YourColumns -- These columns must match in number and datatype with previous SELECT
FROM
TableCore
INNER JOIN TableB AS T ON TableCore.JoinColumn = T.JoinColumn
WHERE
TableCore.CountryFlag = 'global'
However, if the result is still slow, you might want to check if the TableCore table has a index on CountryFlag and JoinColumn, and TableA and TableB an index on JoinColumn.
The basic structure is:
select . . ., coalesce(a.?, b.?) as ?
from tablecore c left join
tablea a
on c.? = a.? and c.countryflag = 'US' left join
tableb b
on c.? b.? and c.counryflag = 'global';
This version of the query can take advantage of indexes on tablea(?) and tableb(?).
If you have a complex query, this portion is probably not responsible for the performance problem.
We have some SQL that is ok on smaller data volumes but poor once we scale up to selecting from larger volumes. Is there a faster alternative style to achieve the same output as below? The idea is to pull back a single unique row to get latest version of the data... The SQL does reference another view but this view runs very fast - so we expect the issue is here below and want to try a different approach
SELECT *
FROM
(SELECT (select CustomerId from PremiseProviderVersionsToday
where PremiseProviderId = b.PremiseProviderId) as CustomerId,
c.D3001_MeterId, b.CoreSPID, a.EnteredBy,
ROW_NUMBER() OVER (PARTITION BY b.PremiseProviderId
ORDER BY a.effectiveDate DESC) AS rowNumber
FROM PremiseMeterProviderVersions a, PremiseProviders b,
PremiseMeterProviders c
WHERE (a.TransactionDateTimeEnd IS NULL
AND a.PremiseMeterProviderId = c.PremiseMeterProviderId
AND b.PremiseProviderId = c.PremiseProviderId)
) data
WHERE data.rowNumber = 1
As Bilal Ayub stated above, the correlated subquery can result in performance issues. See here for more detail. Below are my suggestions:
Change all to explicit joins (ANSI standard)
Use aliases that are more descriptive than single characters (this is mostly to help readers understand what each table does)
Convert data subquery to a temp table or cte (temp tables and ctes usually perform better than subqueries)
Note: normally, you should explicitly create and insert into your temp table but I chose not to do that here as I do not know the data types of your columns.
SELECT d.CustomerId
, c.D3001_MeterId
, b.CoreSPID
, a.EnteredBy
, rowNumber = ROW_NUMBER() OVER(PARTITION BY b.PremiseProviderId ORDER BY a.effectiveDate DESC)
INTO #tmp_RowNum
FROM PremiseMeterProviderVersions a
JOIN PremiseMeterProviders c ON c.PremiseMeterProviderId = a.PremiseMeterProviderId
JOIN PremiseProviders b ON b.PremiseProviderId = c.PremiseProviderId
JOIN PremiseProviderVersionsToday d ON d.PremiseProviderId = b.PremiseProviderId
WHERE a.TransactionDateTimeEnd IS NULL
SELECT *
FROM #tmp_RowNum
WHERE rowNumber = 1
You are running a correlated query that will run in loop, if size of table is small it will be faster, i would suggest to change it and try to join the table in order to get customerid.
(select CustomerId from PremiseProviderVersionsToday where PremiseProviderId = b.PremiseProviderId) as CustomerId
Consider derived tables including an aggregate query that calculates maximum EffectoveDate by PremiseProviderId and unit level query, each using explicit joins (current ANSI SQL standard) and not implicit as you currently use:
SELECT data.*
FROM
(SELECT t.CustomerId, c.D3001_MeterId, b.CoreSPID, a.EnteredBy,
b.PremiseProviderId, a.EffectiveDate
FROM PremiseMeterProviders c
INNER JOIN PremiseMeterProviderVersions a
ON a.PremiseMeterProviderId = c.PremiseMeterProviderId
AND a.TransactionDateTimeEnd IS NULL
INNER JOIN PremiseProviders b
ON b.PremiseProviderId = c.PremiseProviderId
INNER JOIN PremiseProviderVersionsToday t
ON t.PremiseProviderId = b.PremiseProviderId
) data
INNER JOIN
(SELECT b.PremiseProviderId, MAX(a.EffectiveDate) As MaxEffDate
FROM PremiseMeterProviders c
INNER JOIN PremiseMeterProviderVersions a
ON a.PremiseMeterProviderId = c.PremiseMeterProviderId
AND a.TransactionDateTimeEnd IS NULL
INNER JOIN PremiseProviders b
ON b.PremiseProviderId = c.PremiseProviderId
GROUP BY b.PremiseProviderId
) agg
ON data.PremiseProviderId = agg.PremiseProviderId
AND data.EffectiveDate = agg.MaxEffDate
I am building a complex select statement, and when one of my values (pcf_auto_key) is null it will not disipaly any values for that header entry.
select c.company_name, h.prj_number, h.description, s.status_code, h.header_notes, h.cm_udf_001, h.cm_udf_002, h.cm_udf_008, l.classification_code
from project_header h, companies c, project_status s, project_classification l
where exists
(select company_name from companies where h.cmp_auto_key = c.cmp_auto_key)
and exists
(select status_code from project_status s where s.pjs_auto_key = h.pjs_auto_key)
and exists
(select classification_code from project_classification where h.pcf_auto_key = l.pcf_auto_key)
and pjm_auto_key = 11
--and pjt_auto_key = 10
and c.cmp_auto_key = h.cmp_auto_key
and h.pjs_auto_key = s.pjs_auto_key
and l.pcf_auto_key = h.pcf_auto_key
and s.status_type = 'O'
How does my select statement look? Is this an appropriate way of pulling info from other tables?
This is an oracle database, and I am using SQL Developer.
Assuming you want to show all the data that you can find but display the classification as blank when there is no match in that table, you can use a left outer join; which is much clearer with explicit join syntax:
select c.company_name, h.prj_number, h.description, s.status_code, h.header_notes,
h.cm_udf_001, h.cm_udf_002, h.cm_udf_008, l.classification_code
from project_header h
join companies c on c.cmp_auto_key = h.cmp_auto_key
join project_status s on s.pjs_auto_key = h.pjs_auto_key
left join project_classification l on l.pcf_auto_key = h.pcf_auto_key
where pjm_auto_key = 11
and s.status_type = 'O'
I've taken out the exists conditions as they just seem to be replicating the join conditions.
If you might not have matching data in any of the other tables you can make the other inner joins into outer joins in the same way, but be aware that if you outer join to project_status you will need to move the statatus_type check into the join condition as well, or Oracle will convert that back into an inner join.
Read more about the different kinds of joins.
Not sure if this can be done, but here is what I am trying to do.
I have two tables:
Table 1 is called Task and it contains all of the possible Task Names
Table 2 is called Task_subset and it contains only a subset of the Task Names included in Table 1
I have a variable called #TaskControl, that is passed in as a parameter, it either is equal to Table1 or Table2
Based on the value of the #TaskControl variable I want to join one of my Task Tables
For example:
If #TaskControl = 'Table1':
Select * From Orders O Join Task T on T.id = O.id
If #TaskControl = 'Table2):
Select * From Orders O Join Task_subset T on T.id = O.id
How would I do this, Sql Server 08
Don't overcomplicate it. Put it into a stored proc like so:
CREATE PROCEDURE dbo.MyProcedure(#TaskControl varchar(20))
AS
If #TaskControl = 'Table1'
Select * From Orders O Join Task T on T.id = O.id
ELSE If #TaskControl = 'Table2'
Select * From Orders O Join Task_subset T on T.id = O.id
ELSE SELECT 'Invalid Parameter'
Or just straight TSQL with no proc:
If #TaskControl = 'Table1'
Select * From Orders O Join Task T on T.id = O.id
ELSE If #TaskControl = 'Table2'
Select * From Orders O Join Task_subset T on T.id = O.id
Doing it exactly as you do it right now is the best way. Having one single statement that attempts to somehow dynamically join one of two statements is the last thing you want. T-SQL is a language for data access, not for DRY code-reuse programming. If you attempt to have a single statement then the optimizer has to come up with a plan that always work, no matter the value of #TaskControl, and so the plan will always have to join both tables.
A more lengthy discussion on this topic is Dynamic Search Conditions in T-SQL (your dynamic join falls into the same topic as dynamic search).
If they are UNION compatible you could give this a shot. From a quick test this end it only appears to access the relevant table.
I do agree more with JNK's and Remus's answers however. This does have a recompilation cost for every invocation and not much benefit.
;WITH T AS
(
SELECT 'Table1' AS TaskControl, id
FROM Task
UNION ALL
SELECT 'Table2' AS TaskControl, id
FROM Task_subset
)
SELECT *
FROM T
JOIN Orders O on T.id = O.id
WHERE TaskControl = #TaskControl
OPTION (RECOMPILE)
I don't know how good performance would be, and this would not scale well as you add on additional optional tables, but this should work in the situation that you present.
SELECT
O.some_column,
COALESCE(T.some_task_column, TS.some_task_subset_column)
FROM
Orders O
LEFT OUTER JOIN Tasks T ON
#task_control = 'Tasks' AND
T.id = O.id
LEFT OUTER JOIN Task_Subsets TS ON
#task_control = 'Task Subsets' AND
TS.id = O.id
Try the following. It should avoid the stored procedure plan getting bound based on the value of the parameter passed during the first execution of the stored procedure (See SQL Server Parameter Sniffing for details):
create proc dbo.foo
#TaskControl varchar(32)
as
declare #selection varchar(32)
set #selection = #TaskControl
select *
from dbo.Orders t
join dbo.Task t1 on t1.id = t.id
where #selection = 'Table1'
UNION ALL
select *
from dbo.Orders t
join dbo.Task_subset t1 on t1.id = t.id
where #selection = 'Table2'
return 0
go
The stored procedure shouldn't get recompiled for each invocation, either, as #Martin suggested might happen, but the parameter value 1st passed in should not influence the execution plan the gets bound. But if performance is an issue, run a sql trace with the profiler and see if the cached execution plan is reused or if a recompile is triggered.
One thing, though: you will need to ensure, though, that each individual select in the UNION returns the exact same columns. Each select in a UNION must have the same number of columns and each column must have a common type (or default conversion to the common type). The 1st select defines the number, types and names of the columns in the result set.