i have a Stored Procedure which returns output as a ref cursor. I would like to store the output in another table using the MERGE statement. I'm having problems however mixing all the statements together (WITH, USING, MERGE etc..).
Can somebody assist? Thanks!
This is the table i want the output in (STOP_TIME is left out on purpose):
TABLE: **USER_ALLOCATION**
START_TIME date NOT NULL Primary Key
USER_ID number NOT NULL Primary Key
TASK_ID number NULL
This is the SP:
create or replace
PROCEDURE REPORT_PLAN_AV_USER
(
from_dt IN date,
to_dt IN date,
sysur_key IN number,
v_reservations OUT INTRANET_PKG.CURSOR_TYPE
)
IS
BEGIN
OPEN v_reservations FOR
with
MONTHS as (select FROM_DT + ((ROWNUM-1) / (24*2)) as DT from DUAL connect by ROWNUM <= ((TO_DT - FROM_DT) * 24*2) + 1),
TIMES as (select DT as START_TIME,(DT + 1/48) as STOP_TIME from MONTHS where TO_NUMBER(TO_CHAR(DT,'HH24')) between 8 and 15 and TO_NUMBER(TO_CHAR(DT,'D')) not in (1,7))
select
TIMES.START_TIME,
TIMES.STOP_TIME,
T.TASK_ID,
sysur_key USER_ID,
from
TIMES
left outer join (ALLOCATED_USER u INNER JOIN REQUIRED_RESOURCE r ON u.AU_ID = r.RR_ID INNER JOIN TASK t ON r.TASK_ID = t.TASK_ID)
ON u.USER_ID = sysur_key AND t.PLAN_TYPE = 3 AND TIMES.start_time >= TRUNC30(t.START_DATE) AND TIMES.start_time < TRUNC30(t.FINISH_DATE)
where u.USER_ID is null OR u.USER_ID = sysur_key
order by START_TIME ASC;
END;
I don't think you can resuse the cursor unless you write a lot of procedural code.
Can't you write a single merge statement and drop procedure REPORT_PLAN_AV_USER?
If you still need procedure REPORT_PLAN_AV_USE you can create a view that you use in procedure REPORT_PLAN_AV_USER and in your merge statement (to prevent code duplication).
Related
So I'm trying to build a function that returns the records of items that are included in some client subscription.
So I've been building up the following:
2 types:
CREATE OR REPLACE TYPE PGM_ROW AS OBJECT
(
pID NUMBER(10),
pName VARCHAR2(300)
);
CREATE OR REPLACE TYPE PGM_TAB AS TABLE OF PGM_ROW;
1 function:
CREATE OR REPLACE FUNCTION FLOGIN (USER_ID NUMBER) RETURN PGM_TAB
AS
SELECTED_PGM PGM_TAB;
BEGIN
FOR RESTRICTION
IN ( SELECT (SELECT LISTAGG (ID_CHANNEL, ',')
WITHIN GROUP (ORDER BY ID_CHANNEL)
FROM (SELECT DISTINCT CHA2.ID_CHANNEL
FROM CHANNELS_ACCESSES CHA2
JOIN CHANNELS CH2
ON CH2.ID = CHA2.ID_CHANNEL
WHERE CHA2.ID_ACCESS = CMPA.ID_ACCESS
AND CH2.ID_CHANNELS_GROUP = CG.ID))
AS channels,
(SELECT LISTAGG (ID_SUBGENRE, ',')
WITHIN GROUP (ORDER BY ID_SUBGENRE)
FROM (SELECT DISTINCT SGA2.ID_SUBGENRE
FROM SUBGENRES_ACCESSES SGA2
JOIN CHANNELS_ACCESSES CHA2
ON CHA2.ID_ACCESS = SGA2.ID_ACCESS
JOIN CHANNELS CH2
ON CH2.ID = CHA2.ID_CHANNEL
WHERE SGA2.ID_ACCESS = CMPA.ID_ACCESS
AND CH2.ID_CHANNELS_GROUP = CG.ID))
AS subgenres,
CG.NAME,
A.BEGIN_DATE,
A.END_DATE,
CMP.PREVIEW_ACCESS
FROM USERS U
JOIN COMPANIES_ACCESSES CMPA
ON U.ID_COMPANY = CMPA.ID_COMPANY
JOIN COMPANIES CMP ON CMP.ID = CMPA.ID_COMPANY
JOIN ACCESSES A ON A.ID = CMPA.ID_ACCESS
JOIN CHANNELS_ACCESSES CHA
ON CHA.ID_ACCESS = CMPA.ID_ACCESS
JOIN SUBGENRES_ACCESSES SGA
ON SGA.ID_ACCESS = CMPA.ID_ACCESS
JOIN CHANNELS CH ON CH.ID = CHA.ID_CHANNEL
JOIN CHANNELS_GROUPS CG ON CG.ID = CH.ID_CHANNELS_GROUP
WHERE U.ID = USER_ID
GROUP BY CG.NAME,
A.BEGIN_DATE,
A.END_DATE,
CMPA.ID_ACCESS,
CG.ID,
CMP.PREVIEW_ACCESS)
LOOP
SELECT PFT.ID_PROGRAM, PFT.LOCAL_TITLE
BULK COLLECT INTO SELECTED_PGM
FROM PROGRAMS_FT PFT
WHERE PFT.ID_CHANNEL IN
( SELECT TO_NUMBER (
REGEXP_SUBSTR (RESTRICTION.CHANNELS,
'[^,]+',
1,
ROWNUM))
FROM DUAL
CONNECT BY LEVEL <=
TO_NUMBER (
REGEXP_COUNT (RESTRICTION.CHANNELS,
'[^,]+')))
AND PFT.ID_SUBGENRE IN
( SELECT TO_NUMBER (
REGEXP_SUBSTR (RESTRICTION.SUBGENRES,
'[^,]+',
1,
ROWNUM))
FROM DUAL
CONNECT BY LEVEL <=
TO_NUMBER (
REGEXP_COUNT (RESTRICTION.SUBGENRES,
'[^,]+')))
AND (PFT.LAUNCH_DATE BETWEEN RESTRICTION.BEGIN_DATE
AND RESTRICTION.END_DATE);
END LOOP;
RETURN SELECTED_PGM;
END FLOGIN;
I expect the function tu return a table with 2 columns containing all the records from table PROGRAMS_FT that are included in the user access.
For some reason, I'm getting compilation warning ORA-000947.
My understanding of the error code is that it occurs when the values inserted does not match the type of the object receiving the values, and I can't see how this can be the case here.
You're selecting two scalar values and trying to put them into an object. That doesn't happen automatically, you need to convert them to an object:
...
LOOP
SELECT PGM_ROW(PFT.ID_PROGRAM, PFT.LOCAL_TITLE)
BULK COLLECT INTO SELECTED_PGM
FROM PROGRAMS_FT PFT
...
(It's an unhelpful quirk of PL/SQL that it says 'not enough values' rather than 'too many values', as you might expect when you try to put two things into one; I'm sure I came up with a fairly convincing explanation/excuse for that once but it escapes me at the moment...)
I'm not sure your loop makes sense though. Assuming your cursor query returns multiple rows, each time around the loop you're replacing the contents of the SELECTED_PGM collection - you might think you are appending to it, but that's not how it works. So you will end up returning a collection based only on the final iteration of the loop.
Aggregating and then splitting the data seems like a lot of work too. You could maybe use collections for those; but you can probably get rid of the cursor and loop and combine the cursor query with the inner query, which would be more efficient and would allow you to do a single bulk-collect for all the combined data.
Hey guys just here to see if you guys can help me solve this Procedure problem I am running into. Long story short I made a new table called
Create Table ClientHistoricalPurchases(
ClientID varchar2(6) constraint clientidhistorical references Clients,
DistinctProducts number (9),
TotalProducts number(9),
TotalCost number (9,2),
Primary Key (ClientID));
And I want to populate/update this table by running a procedure that reads primarily from the following table:
create table OrderDetails(
OrderID varchar2(6) CONSTRAINT orddetpk PRIMARY KEY,
ProductID varchar2(6) CONSTRAINT prdfk REFERENCES Products ,
UnitPrice number(10,2),
Quantity number(4),
Discount number(3),
ShippingDate date);
I do a couple of joins with two more tables called Orders and Clients but those are trivial joins using the Primary Key's/FK.
So the goal of this procedure is that when I run it I want to loop through order details and I want to calculate the distinct amount of products bought by a Client, the total products and the total purchase amount and I want to update an existing record with the new values if its in the new ClientHistoricalPurchases table if not I want to add a new record for it. So this is what I wrote but its giving me errors:
Create or Replace Procedure Update_ClientHistPurch as
Cursor C1 is
Select orderid, orders.clientid, productid, unitprice, quantity, discount
from orderdetails
Inner join orders on orderdetails.orderid = orders.clientid
for update of TotalCost;
PurchaseRow c1%RowType;
DistinctProducts orderdetails.quantity%type;
TotalProducts orderdetails.quantity%type;
ProposedNewBalance orderdetails.unitprice%type;
Begin
Begin
Begin
Begin
Open C1;
Fetch c1 into PurchaseRow;
While c1% Found Loop
Select count(distinct productid)
into DistinctProducts
from orderdetails
Inner join orders on orderdetails.orderid = orders.orderid
Inner join clients on orders.clientid = clients.clientid
where clients.clientid = purchaserow.clientid;
end;
Select count(ProductID)
into TotalProducts
from orderdetails
Inner join orders on orderdetails.orderid = orders.orderid
Inner join clients on orders.clientid = clients.clientid
where clients.clientid = purchaserow.clientid;
end;
Select sum((unitprice * quantity) - discount)
into ProposedNewBalance
from orderdetails
Inner join orders on orderdetails.orderid = orders.orderid
Inner join clients on orders.clientid = clients.clientid
where clients.clientid = purchaserow.clientid;
end;
If purchaserow.clientid not in ClientHistoricalpurchases.clientid then
insert into ClientHistoricalPurchases values (purchaserow.clientid,DistinctProducts, TotalProducts, ProposedNewBalance);
End if;
If purchaserow.clientid in ClientHistoricalPurchases.clientid then
Update Clienthistoricalpurchases
set clienthistoricalpurchases.distinctproducts = distinctproducts, clienthistoricalpurchases.totalproducts = totalproducts, clienthistoricalpurchases.totalcost = ProposedNewBalance
where purchaserow.clientid = clienthistoricalpurchases.clientid;
end if;
end loop;
end;
Errors are the following:
Error(27,4): PLS-00103: Encountered the symbol ";" when expecting one
of the following: loop The symbol "loop" was substituted for ";"
to continue.
Error(33,7): PLS-00103: Encountered the symbol "JOIN"
when expecting one of the following: , ; for group having
intersect minus order start union where connect
Any help is appreciated guys. Thanks!
In addition to the comments and answers you've already been given, I believe you have massively overcomplicated your procedure. You're doing things very procedurally, rather than thinking in sets as you should be. You are also getting the aggregated columns in three queries that are essentially identical (e.g. same tables, join conditions and predicates) - you could combine them all to get the three results in a single query.
It looks like you're trying to insert into the clienthistoricalpurchases table if a row doesn't already exist for that client, otherwise you update the row. That immediately screams "MERGE statement" to me.
Combining all that, I think your current procedure should contain just a single merge statement:
MERGE INTO clienthistoricalpurchases tgt
USING (SELECT clients.client_id,
COUNT(DISTINCT od.productid) distinct_products,
COUNT(od.productid) total_products,
SUM((od.unitprice * od.quantity) - od.discount) proposed_new_balance
FROM orderdetails od
INNER JOIN orders
ON orderdetails.orderid = orders.orderid
INNER JOIN clients
ON orders.clientid = clients.clientid
GROUP BY clients.client_id) src
ON (tgt.clientid = src.client_id)
WHEN NOT MATCHED THEN
INSERT (tgt.clientid,
tgt.distinctproducts,
tgt.totalproducts,
tgt.totalcost)
VALUES (src.clientid,
src.distinct_products,
src.total_products,
src.proposed_new_balance)
WHEN MATCHED THEN
UPDATE SET tgt.distinctproducts = src.distinct_products,
tgt.totalproducts = src.total_products,
tgt.totalcost = src.proposed_new_balance;
However, I have some concerns over your current logic and/or data model.
It seems like you're expecting at most one row per clientid to appear in clienthistoricalpurchases. What if a clientid has two or more different orders? Currently you would overwrite any existing row.
Also, do you really want to apply this logic across all orders every single time it gets run?
Line 28 of your code, the first END that follows WHILE, should be END LOOP
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 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.