Think of my two tables have the same columns. One column is the ID, and the other one is the text. Is it possible to implement the following pseudo code in PLSQL?
Compare each row (They will have the same ID)
If anything is different about them
Run a couple of queries: an Update, and an Insert
ElseIf they are the same
Do nothing
Else the row does not exist
So add the row to the table compared on
Is it easy to do this using PLSQL or should I create a standalone application to do do this logic.
As your table have the same columns, by using NATURAL JOIN you can easily check if two corresponding rows are identical -- without need to update your code if a column is added to your table.
In addition, using OUTER JOIN allow you to find the rows present in one table but not in the other.
So, you can use something like that to achieve your purpose:
for rec in (
SELECT T.ID ID1,
U.ID ID2,
V.EQ
FROM T
FULL OUTER JOIN U ON T.ID = U.ID
FULL OUTER JOIN (SELECT ID, 1 EQ FROM T NATURAL JOIN U) V ON U.ID = V.ID)
loop
if rec.id1 is null
then
-- row in U but not in T
elsif rec.id2 is null
then
-- row in T but not in U
elsif rec.eq is null
-- row present in both tables
-- but content mismatch
end if
end loop
Else the row does not exist
So add the row to the table compared on
Is this condition means that rows can be missed in both tables? If only in one, then:
insert into t1 (id, text)
select id, text
from t2
minus
select id, text
from t1;
If missed records can be in both tables, you need the same query that inserts into table t2 rows from t1.
If anything is different about them
If you need one action for any amount of different rows, then use something like this:
select count(*)
into a
from t1, t2
where t1.id = t2.id and t1.text <> t2.text;
if a > 0 then
...
otherwise:
for i in (
select *
from t1, t2
where t1.id = t2.id and t1.text <> t2.text) loop
<do something>
end loop;
A 'merge' statement is what u needed.
Here is the syntax:
MERGE INTO TARGET_TABLE
USING SOURCE_TABLE
ON (CONDITION)
WHEN MATCHED THEN
UPDATE SET (DO YOUR UPDATES)
WHEN NOT MATCHED THEN
(INSERT YOUR NEW ROWS)
Google MERGE syntax for more about the statement.
Just use MINUS.
query_1
MINUS
query_2
In your case, if you really want to use PL/SQL, then select count into a local variable. Write a logic, if count > 0 then do other stuff.
Related
This is on 11g. I have an INSERT ALL statement which uses a SELECT to build up the values to insert. The select has some subqueries that check that the record doesn't already exist. The problem is that the insert is taking over 30 minutes, even when there are zero rows to insert. The select statement on its own runs instantly, so the problem seems to be when it is used in conjunction with the INSERT ALL. I rewrote the statement to use MERGE but it was just as bad.
The table has no triggers. There is a primary key index, and a unique constraint on two of the columns, but nothing else that looks like it might be causing an issue. It currently has about 15000 rows, so definitely not big.
Has anyone a suggestion for what might be causing this, or how to go about debugging it?
Here's the INSERT ALL statement.
insert all
into template_letter_merge_fields (merge_field_id, letter_type_id,table_name,field_name,pretty_name, tcl_proc)
values (template_let_mrg_fld_sequence.nextval,letter_type_id,table_name,field_name, pretty_name, tcl_proc)
select lt.letter_type_id,
i.object_type as table_name,
i.interface_key as field_name,
i.pretty_name as pretty_name,
case
when w.widget = 'dynamic_select' then
'dbi::'||i.interface_key||'::get_name'
when w.widget = 'category_tree' and
i.interface_key not like '%_name' and
i.interface_key not like '%_desc' then
'dbi::'||i.interface_key||'::get_name'
else
'dbi::'||i.interface_key||'::get_value'
end as tcl_proc
from template_letter_types lt,
dbi_interfaces i
left outer join acs_attributes aa on (aa.object_type||'_'||aa.attribute_name = i.interface_key
and decode(aa.object_type,'person','party','aims_organisation','party',aa.object_type) = i.object_type)
left outer join flexbase_attributes fa on fa.acs_attribute_id = aa.attribute_id
left outer join flexbase_widgets w on w.widget_name = fa.widget_name
where i.object_type IN (select linked_object_type
from template_letter_object_map lom
where lom.interface_object_type = lt.interface_object_type
union select lt.interface_object_type from dual
union select 'template_letter' from dual)
and lt.interface_object_type = lt.interface_object_type
and not exists (select 1
from template_letter_merge_fields m
where m.sql_code is null
and m.field_name = i.interface_key
and m.letter_type_id = lt.letter_type_id)
and not exists (select 1
from template_letter_merge_fields m2
where m2.pretty_name = i.pretty_name
and m2.letter_type_id = lt.letter_type_id)
I have this table F_Flight which I am trying to insert into from 3 different tables. The first, fourth and fifth columns are from the same, and the second and third columns from different tables. When I execute the code, I get a "single-row subquery returns more than one row" error.
insert when 1 = 1 then into F_Flight (planeid, groupid, dateid, flightduration, kmsflown) values
(planeid, (select b.groupid from BridgeTable b where exists (select p.p1id from pilotkeylookup p where b.pilotid = p.p1id)),
(select dd.id from D_Date dd where exists (select p.launchtime from PilotKeyLookup p where dd."Date" = p.launchtime)),
flightduration, kmsflown) select * from PilotKeyLookup p;
Your subqueries get multiple rows back, which is what the error message says. There is no correlation between the various bits of data and subqueries you're trying to insert into a single row.
This can be done as a much simpler insert...select with joins, something like:
insert into f_flight (planeid, groupid, dateid, flightduration, kmsflown)
select pkl.planeid, bt.groupid, dd.id, pkl.flightduration, pkl.kmsflown
from pilotkeylookup pkl
join bridgetable bt on bt.pilotid = pkl.p1id
join d_date dd on dd."Date" = pkl.launchtime;
This joins the main PilotKeyLookup table to the other two on the keys you used in your subqueries.
Storing an ID value instead of an actual date is unusual, and if launchtime has a time component - which seems likely from the name - and your d_date entries are just dates (i.e. all with time at midnight) then you won't find matches; you might need to do:
join d_date dd on dd."Date" = trunc(pkl.launchtime);
It also seems like this could be a view, as you're storing duplicate data - everything in f_flight could, obviously, be found from the other tables.
I want to copy records from one table to another.
The only records from table 1 that will be copied to table 2 are the ones that still dont exist in table 2.
If duplicate records exists in Table 1 then only be copied to table 2 the record with the larger size name.
I could already implement a query that almost does what I want.
The problem I have is when there are names with the same maximum size of characters.
In these cases, my query returns more than one record and I just want to insert one new record in table 2.
Does anyone know how I can fix this?
Here is my code:
For x in (Select distinct xdd.id_t, xdd.name_t
From table1 xdd
Where xdd.id_t not in (Select distinct det.id_t2
From table2 det)
And LENGTH(xdd.name_t) in (Select Max(LENGTH(xdd2.name_t))
From table1 xdd2
Where xdd2.id_t = xdd.id_t)
) Loop
Insert into id_t2 (id_t2, name_t2)
Values (x.id_t, x.name_t);
End loop;
Can you give me an example to solve this?
Sure. If I understood requirements correctly, then the merge statement will look similar to this one:
We use row_number() analytic function to choose a duplicate record with longer name_t
merge into table_two t2
using(
select id_t
, name_t
from (select id_t
, name_t
, row_number() over(partition by id_t
order by length(name_t) desc) as rn
from table_one) q
where q.rn = 1
) t1
on (t2.id_t = t1.id_t)
when not matched then
insert(id_t, name_t)
values(t1.id_t, t1.name_t)
SQLFiddle demo
This is a merge statement that should "upsert" data from table 1 into table 2. Matching keys should update only when the name field in table1 is greater than that of table 2. And inserts should occur when keys from table one are not matched to table 2.
MERGE INTO table2 D
USING (SELECT table1.id_t, table1.name_t FROM table1) S
ON (D.id_t2 = S.id_t)
WHEN MATCHED THEN UPDATE SET D.name_t2 = S.name_t
WHERE (LENGTH(S.name_t) > LENGTH(D.name_t2))
WHEN NOT MATCHED THEN INSERT (D.id_t, D.name_t)
VALUES (S.id_t2, S.name_t2);
I've faced with a weird problem now. The query itself is huge so I'm not going to post it here (I could post however in case someone needs to see). Now I have a table ,TABLE1, with a CHAR(1) column, COL1. This table column is queried as part of my query. When I filter the recordset for this column I say:
WHERE TAB1.COL1=1
This way the query runs and returns a very big resultset. I've recently updated one of the subqueries to speed up the query. But after this when I write WHERE TAB1.COL1=1 it does not return anything, but if I change it to WHERE TAB1.COL1='1' it gives me the records I need. Notice the WHERE clause with quotes and w/o them. So to make it more clear, before updating one of the sub-queries I did not have to put quotes to check against COL1 value, but after updating I have to. What feature of Oracle is it that I'm not aware of?
EDIT: I'm posting the tw versions of the query in case someone might find it useful
Version 1:
SELECT p.ssn,
pss.pin,
pd.doc_number,
p.surname,
p.name,
p.patronymic,
to_number(p.sex, '9') as sex,
citiz_c.short_name citizenship,
p.birth_place,
p.birth_day as birth_date,
coun_c.short_name as country,
di.name as leg_city,
trim( pa.settlement
|| ' '
|| pa.street) AS leg_street,
pd.issue_date,
pd.issuing_body,
irs.irn,
irs.tpn,
irs.reg_office,
to_number(irs.insurer_type, '9') as insurer_type,
TO_CHAR(sa.REG_CODE)
||CONVERT_INT_TO_DOUBLE_LETTER(TO_NUMBER(SUBSTR(TO_CHAR(sa.DOSSIER_NR, '0999999'), 2, 3)))
||SUBSTR(TO_CHAR(sa.DOSSIER_NR, '0999999'), 5, 4) CONVERTED_SSN_DOSSIER_NR,
fa.snr
FROM
(SELECT pss_t.pin,
pss_t.ssn
FROM EHDIS_INSURANCE.pin_ssn_status pss_t
WHERE pss_t.difference_status < 5
) pss
INNER JOIN SSPF_CENTRE.file_archive fa
ON fa.ssn = pss.ssn
INNER JOIN SSPF_CENTRE.persons p
ON p.ssn = fa.ssn
INNER JOIN
(SELECT pd_2.ssn,
pd_2.type,
pd_2.series,
pd_2.doc_number,
pd_2.issue_date,
pd_2.issuing_body
FROM
--The changed subquery starts here
(SELECT ssn,
MIN(type) AS type
FROM SSPF_CENTRE.person_documents
GROUP BY ssn
) pd_1
INNER JOIN SSPF_CENTRE.person_documents pd_2
ON pd_2.type = pd_1.type
AND pd_2.ssn = pd_1.ssn
) pd
--The changed subquery ends here
ON pd.ssn = p.ssn
INNER JOIN SSPF_CENTRE.ssn_archive sa
ON p.ssn = sa.ssn
INNER JOIN SSPF_CENTRE.person_addresses pa
ON p.ssn = pa.ssn
INNER JOIN
(SELECT i_t.irn,
irs_t.ssn,
i_t.tpn,
i_t.reg_office,
(
CASE i_t.insurer_type
WHEN '4'
THEN '1'
ELSE i_t.insurer_type
END) AS insurer_type
FROM sspf_centre.irn_registered_ssn irs_t
INNER JOIN SSPF_CENTRE.insurers i_t
ON i_t.irn = irs_t.new_irn
OR i_t.old_irn = irs_t.old_irn
WHERE irs_t.is_registration IS NOT NULL
AND i_t.is_real IS NOT NULL
) irs ON irs.ssn = p.ssn
LEFT OUTER JOIN SSPF_CENTRE.districts di
ON di.code = pa.city
LEFT OUTER JOIN SSPF_CENTRE.countries citiz_c
ON p.citizenship = citiz_c.numeric_code
LEFT OUTER JOIN SSPF_CENTRE.countries coun_c
ON pa.country_code = coun_c.numeric_code
WHERE pa.address_flag = '1'--Here's the column value with quotes
AND fa.form_type = 'Q3';
And Version 2:
SELECT p.ssn,
pss.pin,
pd.doc_number,
p.surname,
p.name,
p.patronymic,
to_number(p.sex, '9') as sex,
citiz_c.short_name citizenship,
p.birth_place,
p.birth_day as birth_date,
coun_c.short_name as country,
di.name as leg_city,
trim( pa.settlement
|| ' '
|| pa.street) AS leg_street,
pd.issue_date,
pd.issuing_body,
irs.irn,
irs.tpn,
irs.reg_office,
to_number(irs.insurer_type, '9') as insurer_type,
TO_CHAR(sa.REG_CODE)
||CONVERT_INT_TO_DOUBLE_LETTER(TO_NUMBER(SUBSTR(TO_CHAR(sa.DOSSIER_NR, '0999999'), 2, 3)))
||SUBSTR(TO_CHAR(sa.DOSSIER_NR, '0999999'), 5, 4) CONVERTED_SSN_DOSSIER_NR,
fa.snr
FROM
(SELECT pss_t.pin,
pss_t.ssn
FROM EHDIS_INSURANCE.pin_ssn_status pss_t
WHERE pss_t.difference_status < 5
) pss
INNER JOIN SSPF_CENTRE.file_archive fa
ON fa.ssn = pss.ssn
INNER JOIN SSPF_CENTRE.persons p
ON p.ssn = fa.ssn
INNER JOIN
--The changed subquery starts here
(SELECT ssn,
type,
series,
doc_number,
issue_date,
issuing_body
FROM
(SELECT ssn,
type,
series,
doc_number,
issue_date,
issuing_body,
ROW_NUMBER() OVER (partition BY ssn order by type) rn
FROM SSPF_CENTRE.person_documents
)
WHERE rn = 1
) pd --
--The changed subquery ends here
ON pd.ssn = p.ssn
INNER JOIN SSPF_CENTRE.ssn_archive sa
ON p.ssn = sa.ssn
INNER JOIN SSPF_CENTRE.person_addresses pa
ON p.ssn = pa.ssn
INNER JOIN
(SELECT i_t.irn,
irs_t.ssn,
i_t.tpn,
i_t.reg_office,
(
CASE i_t.insurer_type
WHEN '4'
THEN '1'
ELSE i_t.insurer_type
END) AS insurer_type
FROM sspf_centre.irn_registered_ssn irs_t
INNER JOIN SSPF_CENTRE.insurers i_t
ON i_t.irn = irs_t.new_irn
OR i_t.old_irn = irs_t.old_irn
WHERE irs_t.is_registration IS NOT NULL
AND i_t.is_real IS NOT NULL
) irs ON irs.ssn = p.ssn
LEFT OUTER JOIN SSPF_CENTRE.districts di
ON di.code = pa.city
LEFT OUTER JOIN SSPF_CENTRE.countries citiz_c
ON p.citizenship = citiz_c.numeric_code
LEFT OUTER JOIN SSPF_CENTRE.countries coun_c
ON pa.country_code = coun_c.numeric_code
WHERE pa.address_flag = 1--Here's the column value without quotes
AND fa.form_type = 'Q3';
I've put separating comments for the changed subqueries and the WHERE clause in both queries. Both versions of the subqueries return the same result, one of them is just slower, which is why I decided to update it.
With the most simplistic example I can't reproduce your problem on 11.2.0.3.0 or 11.2.0.1.0.
SQL> create table tmp_test ( a char(1) );
Table created.
SQL> insert into tmp_test values ('1');
1 row created.
SQL> select *
2 from tmp_test
3 where a = 1;
A
-
1
If I then insert a non-numeric value into the table I can confirm Chris' comment "that Oracle will rewrite tab1.col1 = 1 to to_number(tab1.col1) = 1", which implies that you only have numeric characters in the column.
SQL> insert into tmp_test values ('a');
1 row created.
SQL> select *
2 from tmp_test
3 where a = 1;
ERROR:
ORA-01722: invalid number
no rows selected
If you're interested in tracking this down you should gradually reduce the complexity of the query until you have found a minimal, reproducible, example. Oracle can pre-compute a conversion to be used in a JOIN, which as your query is complex seems like a possible explanation of what's happening.
Oracle explicitly recommends against using implicit conversion so it's wiser not to use it at all; as you're finding out. For a start there's no guarantees that your indexes will be used correctly.
Oracle recommends that you specify explicit conversions, rather than rely on implicit or automatic conversions, for these reasons:
SQL statements are easier to understand when you use explicit data type conversion functions.
Implicit data type conversion can have a negative impact on performance, especially if the data type of a column value is converted to that of a constant rather than the other way around.
Implicit conversion depends on the context in which it occurs and may not work the same way in every case. For example, implicit conversion from a datetime value to a VARCHAR2 value may return an unexpected year depending on the value of the NLS_DATE_FORMAT
parameter.
Algorithms for implicit conversion are subject to change across software releases and among Oracle products. Behavior of explicit conversions is more predictable.
If you do only have numeric characters in the column I would highly recommend changing this to a NUMBER(1) column and I would always recommend explicit conversion to avoid a lot of pain in the longer run.
It's hard to tell without the actual query. What I would expect is that TAB1.COL1 is in some way different before and after the refactoring.
Candidates differences are Number vs. CHAR(1) vs. CHAR(x>1) vs VARCHAR2
It is easy to introduce differences like this with subqueries where you join two tables which have different types in the join column and you return different columns in your subquery.
To hunt that issue down you might want to check the exact datatypes of your query. Not sure how to do that right now .. but an idea would be to put it in a view and use sqlplus desc on it.
Recently I fixed the some bug: there was rownum in the join condition.
Something like this: left join t1 on t1.id=t2.id and rownum<2. So it was supposed to return only one row regardless of the “left join”.
When I looked further into this, I realized that I don’t understand how Oracle evaluates rownum in the "left join" condition.
Let’s create two sampe tables: master and detail.
create table MASTER
(
ID NUMBER not null,
NAME VARCHAR2(100)
)
;
alter table MASTER
add constraint PK_MASTER primary key (ID);
prompt Creating DETAIL...
create table DETAIL
(
ID NUMBER not null,
REF_MASTER_ID NUMBER,
NAME VARCHAR2(100)
)
;
alter table DETAIL
add constraint PK_DETAIL primary key (ID);
alter table DETAIL
add constraint FK_DETAIL_MASTER foreign key (REF_MASTER_ID)
references MASTER (ID);
prompt Disabling foreign key constraints for DETAIL...
alter table DETAIL disable constraint FK_DETAIL_MASTER;
prompt Loading MASTER...
insert into MASTER (ID, NAME)
values (1, 'First');
insert into MASTER (ID, NAME)
values (2, 'Second');
commit;
prompt 2 records loaded
prompt Loading DETAIL...
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (1, 1, 'REF_FIRST1');
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (2, 1, 'REF_FIRST2');
insert into DETAIL (ID, REF_MASTER_ID, NAME)
values (3, 1, 'REF_FIRST3');
commit;
prompt 3 records loaded
prompt Enabling foreign key constraints for DETAIL...
alter table DETAIL enable constraint FK_DETAIL_MASTER;
set feedback on
set define on
prompt Done.
Then we have this query :
select * from master t
left join detail d on d.ref_master_id=t.id
The result set is predictable: we have all the rows from the master table and 3 rows from the detail table that matched this condition d.ref_master_id=t.id.
Result Set
Then I added “rownum=1” to the join condition and the result was the same
select * from master t
left join detail d on d.ref_master_id=t.id and rownum=1
The most interesting thing is that I set “rownum<-666” and got the same result again!
select * from master t
left join detail d on d.ref_master_id=t.id and rownum<-666.
Due to the result set we can say that this condition was evaluated as “True” for 3 rows in the detail table. But if I use “inner join” everything goes as supposed to be.
select * from master t
join detail d on d.ref_master_id=t.id and rownum<-666.
This query doesn’t return any row,because I can't imagine rownum to be less then -666 :-)
Moreover, if I use oracle syntax for outer join, using “(+)” everything goes well too.
select * from master m ,detail t
where m.id=t.ref_master_id(+) and rownum<-666.
This query doesn’t return any row too.
Can anyone tell me, what I misunderstand with outer join and rownum?
ROWNUM is a pseudo-attribute of result sets, not of base tables. ROWNUM is defined after rows are selected, but before they're sorted by an ORDER BY clause.
edit: I was mistaken in my previous writeup of ROWNUM, so here's new information:
You can use ROWNUM in a limited way in the WHERE clause, for testing if it's less than a positive integer only. See ROWNUM Pseudocolumn for more details.
SELECT ... WHERE ROWNUM < 10
It's not clear what value ROWNUM has in the context of a JOIN clause, so the results may be undefined. There seems to be some special-case handling of expressions with ROWNUM, for instance WHERE ROWNUM > 10 always returns false. I don't know how ROWNUM<-666 works in your JOIN clause, but it's not meaningful so I would not recommend using it.
In any case, this doesn't help you to fetch the first detail row for each given master row.
To solve this you can use analytic functions and PARTITION, and combine it with Common Table Expressions so you can access the row-number column in a further WHERE condition.
WITH numbered_cte AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY t.id ORDER BY d.something) AS rn
FROM master t LEFT OUTER JOIN detail d ON d.ref_master_id = t.id
)
SELECT *
FROM numbered_cte
WHERE rn = 1;
if you want to get the first three values from the join condition change the select statement like this.
select *
from (select *
from master t left join detail d on d.ref_master_id=t.id)
where rownum<3;
You will get the required output. Take care on unambigiously defined column names when using *
Let me give an absolute answer which u can run directly with out making any changes to the code.
select *
from (select t.id,t.name,d.id,d.ref_master_id,d.name
from master t left join detail d on d.ref_master_id=t.id)
where rownum<3;
A ROWNUM filter doesn't make any sense in a join, but it isn't being rejected as invalid.
The explain plan will either include the ROWNUM filter or exclude it. If it includes it, it will apply the filter to the detail table after applying the other join condition(s). So if you put in ROWNUM=100 (which will never be satisfied) all the detail rows are excluded and then the outer join kicks in.
If you put in ROWNUM=1 it seems to drop the filter.
And if you query
with
a as (select rownum a_val from dual connect by level < 10),
b as (select rownum*2 b_val from dual connect by level < 10)
select * from a left join b on a_val < b_val and rownum in (1,3);
you get something totally weird.
It probably should be rejected as an error, so expect nonsensical things to happen