How would my output change if I remove exists statement from the following query.
UPDATE AR_CRDT C
set (OPERATOR_ID,UPDT_TS) = ( SELECT AD.OPERATOR_ID,sysdate
FROM
(
Select A.*
FROM AR1_CUSTOMER_CREDIT A
)AD
WHERE AD.CREDIT_ID = C.CRDT_ID
)
where exists ( SELECT 1
FROM
(
Select A.*
FROM AR1_CUSTOMER_CREDIT A
)AD
WHERE AD.CREDIT_ID = C.CRDT_ID
);
If you remove the exists, then OPERATOR_ID and UPDT_TS would be set to NULL for rows where the conditions do not match.
Why would you write this with the extra subqueries?
UPDATE AR_CRDT C
SET (OPERATOR_ID, UPDT_TS) = (SELECT AD.OPERATOR_ID, sysdate
FROM AR1_CUSTOMER_CREDIT A
WHERE A.CREDIT_ID = C.CRDT_ID
)
WHERE EXISTS (SELECT 1
FROM AR1_CUSTOMER_CREDIT A
WHERE A.CREDIT_ID = C.CRDT_ID
);
The EXISTS currently causes the updates to AR_CRDT to be limited to those records where the AR_CRDT record is associated with an AR1_CUSTOMER_CREDIT record.
Removing that clause will mean that ALL records of AR_CRDT will be updated. Some will have values for the sub-query and some will be NULL where there is no link between AR_CRDT and AR1_CUSTOMER_CREDIT.
Related
My query should stop inserting values, as the not exists statement is satisfied (I have checked both tables) and matching incidents exist in both tables, any ideas why values are still being returned?
Here is the code:
INSERT INTO
odwh_system.ead_incident_credit_control_s
(
incident
)
SELECT DISTINCT
tp.incident
FROM
odwh_data.ead_incident_status_audit_s ei
INNER JOIN odwh_data.ead_incident_s tp ON ei.incident=tp.incident
WHERE
ei.status = 6
OR
ei.status = 7
AND NOT EXISTS
(
SELECT
true
FROM
odwh_system.ead_incident_credit_control_s ead
WHERE
ead.incident = tp.incident
)
AND EXISTS
(
SELECT
true
FROM
odwh_work.ead_incident_tp_s tp
WHERE
tp.incident = ei.incident
);
dont reuse table aliases
use sane aliases
avoid AND/OR conflicts; prefer IN()
INSERT INTO odwh_system.ead_incident_credit_control_s (incident)
SELECT -- DISTINCT
tp.incident
FROM odwh_data.ead_incident_s dtp
WHERE NOT EXISTS (
SELECT *
FROM odwh_system.ead_incident_credit_control_s sic
WHERE sic.incident = dtp.incident
)
AND EXISTS (
SELECT *
FROM odwh_work.ead_incident_tp_s wtp
JOIN odwh_data.ead_incident_status_audit_s dis ON wtp.incident = dis.incident AND dis.status IN (6 ,7)
WHERE wtp.incident = dtp.incident
);
I have table1 and table2 (both have the same columns), I want to insert all records in table2 into table1 if they do not exists in table1, overwise I want to update table1's columns with all non NULL columns of table2.
I didnt manage to find a way to produce one sql that does both things.
As for the first part i manged with INSERT OR IGNORE.
The 2nd part is the problem.
This is what i have:
UPDATE main.datas
SET ot=(
SELECT ot FROM cards.datas
WHERE main.datas.id = cards.datas.id AND cards.datas.ot <> NULL
);
problem is, is that the whole (SELECT...) return NULL because of the cards.datas.ot <> NULL part. i tried doing cards.datas.ot IS NOT NULL instead but it just ignores it and sets NULL values as well.
Put the WHERE ... IS NOT NULL condition in the UPDATE statement:
UPDATE main.datas
SET ot = (SELECT ot FROM cards.datas WHERE main.datas.id = cards.datas.id)
WHERE (SELECT ot FROM cards.datas WHERE main.datas.id = cards.datas.id) is not null
or use coalesce():
UPDATE main.datas
SET ot=coalesce((
SELECT ot FROM cards.datas
WHERE main.datas.id = cards.datas.id AND cards.datas.ot IS NOT NULL
), ot);
The typical way to write this uses not exists:
UPDATE main.datas md
SET ot = (SELECT cd.ot
FROM cards.datas cd
WHERE md.id = cd.id AND cd.ot IS NOT NULL
)
WHERE NOT EXISTS (SELECT cd.ot
FROM cards.datas cd
WHERE md.id = cd.id AND cd.ot IS NOT NULL
);
This runs the risk of an error if the first subquery returns more than one row. For that reason, you might want to include LIMIT 1 or an aggregation function.
So, i have two tables, the target table and the source one. I need to delete the rows that exists in the target table, but doesn't exists in the source table.
And the code:
MERGE INTO (SELECT id_car_bk, car_brand_bk, car_type_bk, new_car
FROM car_catalog_backup) CB
USING (SELECT id_car, car_brand, car_type FROM car_catalog) C
ON (CB.id_car_bk = b.id_car)
WHEN NOT MATCHED THEN
INSERT
(CB.id_car_bk, CB.car_brand_bk, CB.car_type_bk)
VALUES
(C.id_car, C.car_brand, C.car_type)
WHEN MATCHED THEN
UPDATE SET CB.car_brand_bk = C.car_brand;
You can use
DELETE car_catalog_backup b
WHERE not exists
( SELECT 0
FROM car_catalog c
WHERE b.id_car_bk = c.id_car );
or
DELETE car_catalog_backup b
WHERE b.id_car_bk not in
( SELECT c.id_car
FROM car_catalog c );
assuming car_catalog is the source, and car_catalog_backup is the target. The First one is preferable, since it's more performant.
If your aim is to find out with a MERGE statement similar to your case, then use the following
MERGE INTO car_catalog_backup a
USING (SELECT id_car, car_brand, car_type, car_brand_bk
FROM car_catalog
JOIN car_catalog_backup
ON id_car_bk = id_car
) b
ON (a.id_car_bk = b.id_car)
WHEN MATCHED THEN
UPDATE SET a.new_car = 1
DELETE
WHERE a.car_brand_bk != b.car_brand
WHEN NOT MATCHED THEN
INSERT
(id_car_bk, car_brand_bk, car_type_bk)
VALUES
(b.id_car, b.car_brand, b.car_type)
to delete the records matched for id columns ( a.id_car_bk = b.id_car ) but not matched for brand code columns ( a.car_brand_bk != car_brand ) as an example.
Demo
Delete from target
Where not exists
(
Select 1
From source
Where join of source and target
)
With a left join:
DELETE target
FROM target LEFT JOIN source
ON target.someid = source.otherid
WHERE source.otherid IS NULL;
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 need to update a field on a table to be true only if a matching row exists in another table, for all the rows where the column is currently null in the main table.
This is a description of what I want to achieve:
UPDATE [LenqReloaded].[dbo].[Enquiry] A
SET [ResponseLetterSent] = 1
WHERE [ResponseLetterSent] IS NULL
AND EXISTS
(
SELECT * FROM [LenqReloaded].[dbo].[Attachment] B
WHERE A.[EnquiryID] = B.[EnquiryID]
)
This isn't syntactically correct.
I can't code it via an IF EXISTS... statement because I don't have the [EnquiryID] without reading the data from the table.
How should I format my UPDATE statement?
You weren't far off...
UPDATE A
SET A.[ResponseLetterSent] = 1
FROM [LenqReloaded].[dbo].[Enquiry] A
WHERE A.[ResponseLetterSent] IS NULL
AND EXISTS ( SELECT * FROM [LenqReloaded].[dbo].[Attachment] B WHERE A.[EnquiryID] = B.[EnquiryID] )
You need to use a join in your update:
UPDATE [LenqReloaded].[dbo].[Enquiry] SET [ResponseLetterSent] = 1
FROM [LenqReloaded].[dbo].[Enquiry] A
join [LenqReloaded].[dbo].[Attachment] B on A.[EnquiryID] = B.[EnquiryID]
WHERE A.[ResponseLetterSent] IS NULL
This seems counterintuitive, but you need to establish a table alias in a From clause but use that alias in the Update Clause...
Update E Set
ResponseLetterSent = 1
From LenqReloaded.dbo.Enquiry E
Where ResponseLetterSent Is Null
And Exists (Select * From LenqReloaded.dbo.Attachment
Where EnquiryID = E.EnquiryID)
The thing you are missing is the 'from' clause, which is a t-sql extension - it is the only way to assign an alias to the updated table
update [lenqreloaded].[dbo].[enquiry]
set [responselettersent] = 1
from [lenqreloaded].[dbo].[enquiry] a
where [responselettersent] is null
and exists (
select *
from [lenqreloaded].[dbo].[attachment] b
where a.[enquiryid] = b.[enquiryid]
)