I have got two products tables, let's say current_products and historical_products, with the very same structure, and a key in the product_code field.
I have to search a list of product in these tables for further processing.
The trivial solution I've figured out is the following:
SELECT u.*
, u.calculated_fields
, t.other_fields
FROM (
SELECT * FROM current_products
UNION
SELECT * FROM historical_products
) u
JOIN other_tables t
WHERE u.product_code = 'some_prodcut_code'
PROS: DRY
CONS: bad performance
The performance are not the best, so I would like to create a conditional query like this:
IF EXISTS (select * from current_products WHERE product_code = 'some_prodcut_code')
BEGIN
SELECT u.*
, u.calculated_fields
, t.other_fields
FROM current_products u
JOIN other_tables t
WHERE u.product_code = 'some_prodcut_code'
END
ELSE IF EXISTS (select * from historical_products WHERE product_code = 'some_prodcut_code')
BEGIN
SELECT u.*
, u.calculated_fields
, t.other_fields
FROM historical_products u
JOIN other_tables t
WHERE u.product_code = 'some_prodcut_code'
END
PROS: better performance
CONS: NOT DRY
QUESTION
Is there a third way?
performance killing you because you are pulling all records from both table first, THEN applying the where condition... try changing to
FROM (
SELECT * FROM current_products
WHERE product_code = 'some_prodcut_code'
UNION
SELECT * FROM historical_products
WHERE product_code = 'some_prodcut_code'
) u
JOIN other_tables t
This way, the internal query can work against the indexes of the underlying products tables (presuming you HAVE an index on the product_code in the first position, or with other criteria you may want to also apply).
Related
I have two table named Soft and Web, table containing multiple data in that which data is different that data I want. For Ex :
In soft table containing 5 data i.e.
Also in Web table containing 5 data i.e.
Now I want output i.e.
I have done query but unfortunately didnt succed, lets see my query i.e.
SELECT DISTINCT soft.GSTNo AS SoftGST
,web.GSTNo AS WebGST
,soft.InvoiceNumber AS SoftInvoice
,web.InvoiceNumber AS WebInvoice
,soft.Rate AS SoftRate
,web.Rate AS WebRate
FROM soft
LEFT OUTER JOIN web ON web.GstNo = soft.GSTNo
AND web.InvoiceNumber = soft.invoicenumber
AND web.rate = soft.rate
Also I apply inner join bt same thing didnt work.
You can achieve this by
;WITH cte_soft AS
(SELECT * FROM soft
EXCEPT
SELECT * FROM web)
,cte_web AS
(SELECT * FROM web
EXCEPT
SELECT * FROM soft)
SELECT *
FROM
(SELECT gst softgst, NULL webgst, invoice softinvoice, NULL webinvoice, rate softrate, NULL webrate
FROM cte_soft
UNION ALL
SELECT NULL, gst, NULL, invoice, NULL , rate
FROM cte_web) tbl
ORDER BY coalesce(softgst, webgst),coalesce(softinvoice,webinvoice)
Fiddle
You can use full join:
SELECT s.gst as softgst, w.gst as webgst,
s.invoice as softinvoice, w.invoice as webinvoice,
s.rate as softrate, w.rate as webrate
FROM soft s FULL JOIN
web w
ON s.gst = w.gst AND s.invoice = w.invoice AND s.rate = w.rate
WHERE s.gst IS NULL OR w.gst IS NULL
ORDER BY COALESCE(s.gst, w.gst), COALESCE(s.invoice, w.invoice);
No subqueries are CTEs are needed. This is really just a slight variant of your query.
I have a question on sql desgin.
Context:
I have a table called t_master and 13 other tables (lets call them a,b,c... for simplicity) where it needs to compared.
Logic:
t_master will be compared to table 'a' where t_master.gen_val =
a.value.
If record exist in t_master, retrieve t_master record, else retrieve 'a' record.
I do not need to retrieve the records if it exists in both tables (t_master and a) - XOR condition
Repeat this comparison with the remaining 12 tables.
I have some idea on doing this, using WITH to subquery the non-master tables (a,b,c...) first with their respective WHERE clause.
Then use XOR statement to retrieve the records.
Something like
WITH a AS (SELECT ...),
b AS (SELECT ...)
SELECT field1,field2...
FROM t_master FULL OUTER JOIN a FULL OUTER JOIN b FULL OUTER JOIN c...
ON t_master.gen_value = a.value
WHERE ((field1 = x OR field2 = y ) AND NOT (field1 = x AND field2 = y))
AND ....
.
.
.
.
Seeing that I have 13 tables that I need to full outer join, is there a better way/design to handle this?
Otherwise I would have at least 2*13 lines of WHERE clause which I'm not sure if that will have impact on the performance as t_master is sort of a log table.
**Assume I cant change any schema.
Currently I'm not sure if this SQL will working correctly yet, so I'm hoping someone can guide me in the right direction regarding this.
update from used_by_already's suggestion:
This is what I'm trying to do (comparison between 2 tables first, before I add more, but I am unable to get values from ATP_R.TBL_HI_HDR HI_HDR as it is in the NOT EXISTS subquery.
How do i overcome this?
SELECT LOG_REPO.UNIQ_ID,
LOG_REPO.REQUEST_PAYLOAD,
LOG_REPO.GEN_VAL,
LOG_REPO.CREATED_BY,
TO_CHAR(LOG_REPO.CREATED_DT,'DD/MM/YYYY') AS CREATED_DT,
HI_HDR.HI_NO R_VALUE,
HI_HDR.CREATED_BY R_CREATED_BY,
TO_CHAR(HI_HDR.CREATED_DT,'DD/MM/YYYY') AS R_CREATED_DT
FROM ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO JOIN ATP_R.TBL_HI_HDR HI_HDR ON LOG_REPO.GEN_VAL = HI_HDR.HI_NO
WHERE NOT EXISTS
(SELECT NULL
FROM ATP_R.TBL_HI_HDR HI_HDR
WHERE LOG_REPO.GEN_VAL = HI_HDR.HI_NO
)
UNION ALL
SELECT LOG_REPO.UNIQ_ID,
LOG_REPO.REQUEST_PAYLOAD,
LOG_REPO.GEN_VAL,
LOG_REPO.CREATED_BY,
TO_CHAR(LOG_REPO.CREATED_DT,'DD/MM/YYYY') AS CREATED_DT,
HI_HDR.HI_NO R_VALUE,
HI_HDR.CREATED_BY R_CREATED_BY,
TO_CHAR(HI_HDR.CREATED_DT,'DD/MM/YYYY') AS R_CREATED_DT
FROM ATP_R.TBL_HI_HDR HI_HDR JOIN ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO ON HI_HDR.HI_NO = LOG_REPO.GEN_VAL
WHERE NOT EXISTS
(SELECT NULL
FROM ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO
WHERE HI_HDR.HI_NO = LOG_REPO.GEN_VAL
)
Full outer joins used to exclude all matching rows can be an expensive query. You don't supply much detail, but perhaps using NOT EXISTS would be simpler and maybe it will produce a better explain plan. Something along these lines.
select
cola,colb,colc
from t_master m
where not exists (
select null from a where m.keycol = a.fk_to_m
)
and not exists (
select null from b where m.keycol = b.fk_to_m
)
and not exists (
select null from c where m.keycol = c.fk_to_m
)
union all
select
cola,colb,colc from a
where not exists (
select null from t_master m where a.fk_to_m = m.keycol
)
union all
select
cola,colb,colc from b
where not exists (
select null from t_master m where b.fk_to_m = m.keycol
)
union all
select
cola,colb,colc from c
where not exists (
select null from t_master m where c.fk_to_m = m.keycol
)
You could union the 13 a,b,c ... tables to simplify the coding, but that may not perform so well.
I have scrapped my previous question as I did not do a good job explaining. Maybe this will be simpler.
I have the following query.
Select * from comp_eval_hdr, comp_eval_pi_xref, core_pi, comp_eval_dtl
where comp_eval_hdr.START_DATE between TO_DATE('01-JAN-16' , 'DD-MON-YY')
and TO_DATE('12-DEC-17' , 'DD-MON-YY')
and comp_eval_hdr.COMP_EVAL_ID = comp_eval_dtl.COMP_EVAL_ID
and comp_eval_hdr.COMP_EVAL_ID = comp_eval_pi_xref.COMP_EVAL_ID
and core_pi.PI_ID = comp_eval_pi_xref.PI_ID
and core_pi.PROGRAM_CODE = 'PS'
Now if I only want a random 100 rows from the comp_eval_hdr table to join with the other tables how would I go about it? If it makes it easier you can disregard the comp_eval_dtl table.
I think you are pretty much there. You just need subqueries, table aliases, and JOIN conditions:
SELECT . . .
FROM (SELECT a.*
FROM (SELECT a.*
FROM a
WHERE a.START_DATE BEWTWEEN DATE '2016-01-01' AND DATE '2017-12-12'
ORDER BY DBMS_RANDOM.VALUE
) a
WHERE ROWNUM <= 100
) a JOIN
mapping m
ON a.? = m.? JOIN
b
ON m.? = b.?;
The ? is just a placeholder for the join columns.
It's a bit of a stretch to know what you want with the question as written but here's my attempt.
WITH rand_list AS
(SELECT * FROM comp_eval_hdr
WHERE comp_eval_hdr.START_DATE BEWTWEEN TO_DATE('01-JAN-16' , 'DD-MON-YY') AND TO_DATE('12-DEC-17' , 'DD-MON-YY')
ORDER BY DBMS_RANDOM.VALUE)
first_100 AS
(SELECT *
FROM rand_list
WHERE ROWNUM <=100)
SELECT md.col_1, t3.col_a
FROM first_100 md
INNER JOIN
table2 t2 ON md.id_column = t2.fk_comp_eval_hdr_id
INNER JOIN
table3 t3 ON t3.id_column = t2.fk_table3_id
You haven't given any indication how they join or the table names and obviously I haven't run this against any mock tables.
You've got a list of randomised records with RAND_LIST which you could, if you wanted, combine with the FIRST_100 query (your choice).
The main query then just joins that through your mapping table (T2) to your 'multiples' table (T3).
how does table 2 look like?...Let me put one example as person table and order table?
select * from (
select * from person ps , order order where ps.city = 'mumbai' and ps.id = order.purchasedby ) porder where porder.rownum <= 100
I did not tested it but it will look something like this.
I have a list of values. I am trying to select from that list all values that do not occur in a table.
for instance
var_nos ['Z1234', 'Z1235, 'Z1236']
select *
from db_table
where db_idno not in var_nos
Is this possible?
** after reading, I'm not sure this makes sense. I want to return the value from var_nos that did not appear in POHED.
Possibly SQL isn't the best way to handle this?
An outer join should do it:
with var_nos (no) as ( values ('Z1234'), ('Z1235'), ('Z1236'))
select no
from var_nos
left outer join
db_table
on db_table.db_idno = var_nos.no
where db_table.db_idno is null
Alternatively:
select no
from table ( values ('Z1234'), ('Z1235'), ('Z1236')) as var_nos (no)
where not exists (
select 1 from db_table where db_table.db_idno = var_nos.no
)
P.S. Not tested.
Rather than creating a list, you could declare a temporary table if you want.
However, you can achieve the same result from the following query. It's not as elegant as creating a temp variable for the list you want to exclude from your results.
SELECT * FROM db_table
WHERE db_idno NOT IN (SELECT db_idno FROM db_table WHERE db_idno NOT IN ('Z1234', 'Z1235, 'Z1236'))
I have tested this in MySQL and it works. Let me know how it goes
You could use 'not in'.
select *
from db_table where db_idno not in (
select * from (
select 'Z1234' db_idno
union select 'Z1235'
union select 'Z1236'
) exclude
)
Tested on MySQL.
You can use UNNEST on an array to turn it into a table
SELECT *
FROM db_table
LEFT JOIN UNNEST(var_nos AS T(var_nos)) ON T.var_nos = db_table.var_nos
WHERE T.var_nos is null
This will only work in an SP.
Suppose I have an sql query like the following (I realize this query could be written better, just bear with me):
SELECT aT.NAME
FROM anothertable aT,
( SELECT ts.slot_id,
tgm.trans_id,
tagm.agent_id
FROM slots ts,
transactions tgm,
agents tagm
WHERE ts.slot_id = (12345, 678910)
and ts.slot_id = tagm.slot_id
AND ts.slot_id = tgm.slot_id) INNER
WHERE INNER.trans_id = aT.trans_id
AND INNER.agent_id = aT.trans_id
Now suppose that I need to break up this query into two parts...in the first I'll execute the inner query, do some processing on the results in code, and then pass back a reduced set to the outer part of the query. The question is, is there an easy way to emulate an inner table in sql?
For instance, if the results of the inner query returned 5 rows but my program deems to only need two of those rows, how can I write sql that will do what I am trying to do below? Is there a way, in sql, to declare a table for in memory in query use?
SELECT
at.Name
FROM
anotherTable aT,
(SLOT_ID, TRANS_ID, AGENT_ID
-------------------------
230743, 3270893, 2307203
078490, 230897, 237021) inner
WHERE
inner.trans_id = at.trans_id
AND INNER.agent_id = aT.trans_id
Just use a subquery:
SELECT at.Name
FROM anotherTable aT JOIN
(select 230743 as SLOT_ID, 3270893 as TRANS_ID, 2307203 as AGENT_ID from dual
select 078490, 230897, 237021 from dual
) i
on i.trans_id = at.trans_id AND i.agent_id = aT.trans_id;
Most systems will let you define a TEMP TABLE or TABLE VARIABLE: https://www.simple-talk.com/sql/t-sql-programming/temporary-tables-in-sql-server/
CREATE TABLE #temp (
SLOT_ID INT,
TRANS_ID INT,
AGENT_ID INT
);
INSERT INTO #temp(SLOT_ID, TRANS_ID, AGENT_ID)
(--inner query goes here)
--do your main query, then:
DROP TABLE #temp
IN MS SQL Server (not sure about other systems), you could possibly use a Common Table Expression (CTE): https://technet.microsoft.com/en-us/library/ms190766%28v=sql.105%29.aspx
WITH inner AS (
--inner query goes here
)
--main select goes here
Personally, since I generally work with MSSQL Server, I use CTE's quite a bit, as they can be created "on the fly", and can be a big help in organizing more complex queries.
The subquery method worked. Since this is Oracle, the syntax turned out to be:
SELECT aT.Name
FROM anotherTable aT,
(select 1907945 as SLOT_ID, 2732985 as TRANS_ID, 40157 as AGENT_ID FROM DUAL
union
select 1907945, 2732985, 40187 FROM DUAL
) inner
WHERE
inner.trans_id = aT.trans_id AND INNER.agent_id = aT.trans_id;