how inner cursor use a field of outer cursor in oracle? - oracle

I have two nested cursors. I mean one cursor Is Inside of another one.
I want to use a field of outer cursor inside the inner one. something like this:
Inner_cursor.outer_cursor.outer_cursor_column;
but It does not work even I use like this:
Inner_cursor.(outer_cursor.outer_cursor_column);
Is there any way I could do this?
EDIT:
This Is My Code:
CREATE OR REPLACE PROCEDURE TEST1
AS
CURSOR loop_relation IS
SELECT * FROM RELATION_table;
relation_rec loop_relation%rowtype;
CURSOR loop_BIG_TABLE IS
SELECT * FROM BIG_TABLE;
BIG_TABLE_rec loop_BIG_TABLE%rowtype;
BEGIN
FOR RELATION_REC IN LOOP_RELATION
LOOP
FOR BIG_TABLE_rec in loop_BIG_TABLE
LOOP
IF (BIG_TABLE_REC.RELATION_REC.DESTINATION_PK IS NULL) THEN
UPDATE BIG_TABLE
SET BIG_TABLE.RELATION_REC.DESTINATION_PK = (
SELECT RELATION_REC.SOURCE_FK FROM RELATION_REC.SOURCE_TABLE
WHERE RELATION_REC.SOURCE_PK = BIG_TABLE_REC.RELATION_REC.SOURCE_PK)
WHERE BIG_TABLE_REC.ID = BIG_TABLE.ID;
END IF;
END LOOP;
END LOOP;
END TEST1;
/
my problem is in the lines that i use three dot(.) to use a value of outer cursor in inner cursor.

Here's an example of two nested cursors and variables from the outer one used in the inner one. I hope it helps you.
BEGIN
FOR r_outer in (
select tab1.field1
from table1 tab1 )
LOOP
FOR r_inner in (
select tab2.field2
from table2 tab2
where tab2.field2 = r_outer.field1 )
LOOP
dbms_output.put_line(r_outer.field1);
dbms_output.put_line(r_inner.field2);
END LOOP;
END LOOP;
END;

For reference, I created a procedure to display how to use outer cursor value inside inner cursor value. I hope this resolves your query.
CREATE OR REPLACE PROCEDURE cur_inside_cur(my_cur OUT sys_refcursor)
AS
CURSOR roy_cur IS
SELECT name FROM avrajit;
roy_cur1 roy_cur%ROWTYPE;
BEGIN
OPEN roy_cur;
LOOP
FETCH roy_cur INTO roy_cur1;
EXIT WHEN roy_cur%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(roy_cur1.name);
OPEN my_cur FOR
SELECT department FROM avrajit
WHERE name=roy_cur1.name;
END LOOP;
END cur_inside_cur;
OUTPUT
var c refcursor;
begin
cur_inside_cur(:c);
end;
print c;

Related

PL/SQL Cursor whose query is based on a variable

I've got a PL/SQL block that's basically
DECLARE
PIDM NUMBER(8);
CLM_TEST_SCORE NUMBER(5);
CURSOR C_STUDENT IS
select PIDM
from SOSC.DW_ALL_COLLECTOR
order by PIDM;
CURSOR C_CLM_SCORES IS
select max(to_number(SORTEST_TEST_SCORE))
from SATURN.SORTEST
where SORTEST_PIDM = pidm;
BEGIN
OPEN C_STUDENT;
LOOP
CLM_TEST_SCORE := '';
FETCH c_Student INTO pidm;
EXIT WHEN c_Student%notfound;
OPEN C_CLM_SCORES;
FETCH C_CLM_SCORES INTO CLM_TEST_SCORE;
CLOSE C_CLM_SCORES;
insert into some_table (CLM_TEST_SCORE)
values (CLM_TEST_SCORE);
END LOOP
END
As far as I'm aware, the pidm referred to in C_CLM_SCORES is the PIDM NUMBER(8) declared in line 2. That would mean that the query the cursor refers to mutates every iteration of the LOOP, depending on the current value of pidm. That doesn't jive with my understanding of cursors as a query-in-progress, as the underlying query changes every LOOP. Maybe it's the original author taking advantage of a clever DB algorithm?
This code works. I just have absolutely no idea why. What the heck is going on here?
You have an overly confusing block of code that is a nightmare to debug as you have:
SQL statements that refer to column name and local variables with the same identifier (PIDM and CLM_TEST_SCORE).
Cursors that change every iteration because they contain a bind variable referring to local variables (PIDM).
Highly inefficient use of loops.
If you want to make it clearer, you can rewrite the PL/SQL block so that you do not have duplicate identifiers and use a parameterised cursor:
DECLARE
v_PIDM SOSC.DW_ALL_COLLECTOR.PIDM%TYPE;
v_CLM_TEST_SCORE some_table.CLM_TEST_SCORE%TYPE;
CURSOR C_STUDENT IS
select PIDM
from SOSC.DW_ALL_COLLECTOR
order by PIDM;
CURSOR C_CLM_SCORES(p_pidm NUMBER) IS
select max(to_number(SORTEST_TEST_SCORE))
from SATURN.SORTEST
where SORTEST_PIDM = p_pidm;
BEGIN
OPEN C_STUDENT;
LOOP
FETCH c_Student INTO v_pidm;
EXIT WHEN c_Student%notfound;
OPEN C_CLM_SCORES(v_pidm);
FETCH C_CLM_SCORES INTO v_CLM_TEST_SCORE;
CLOSE C_CLM_SCORES;
insert into some_table (CLM_TEST_SCORE)
values (v_CLM_TEST_SCORE);
END LOOP;
END;
/
However, that is still very inefficient as each iteration performs a SELECT and an INSERT and will generate log entries. You can make it much simpler and more efficient to rewrite the whole thing as a single SQL statement:
INSERT INTO some_table (clm_test_score)
SELECT ( select max(to_number(SORTEST_TEST_SCORE))
from SATURN.SORTEST s
where s.SORTEST_PIDM = c.pidm )
FROM SOSC.DW_ALL_COLLECTOR c;
db<>fiddle here
The code in the question is an advertisement for "Why should implicit cursors be used?". If you rewrite your code as below it becomes much easier to understand:
BEGIN
FOR rowStudent IN (select PIDM
from SOSC.DW_ALL_COLLECTOR
order by PIDM)
LOOP
FOR rowScores IN (select max(to_number(SORTEST_TEST_SCORE)) AS CLM_TEST_SCORE
from SATURN.SORTEST
where SORTEST_PIDM = rowStudent.PIDM)
LOOP
insert into some_table (CLM_TEST_SCORE)
values (rowScores.CLM_TEST_SCORE);
END LOOP; -- rowScores
END LOOP; -- rowStudent
END;
This eliminates all of the variables and cursor definitions, and all the code is right in front of you where you can see it at a glance.
If you wanted to tighten it up a bit further you could use a join to get down to just one cursor:
BEGIN
FOR rowStudent_scores IN (SELECT d.PIDM, MAX(TO_NUMBER(s.SORTEST_TEST_SCORE)) AS CLM_TEST_SCORE
FROM SOSC.DW_ALL_COLLECTOR d
INNER JOIN SATURN.SORTEST s
ON s.SORTEST_PIDM = d.PIDM
GROUP BY d.PIDM)
LOOP
insert into some_table (CLM_TEST_SCORE)
values (rowStudent_scores.CLM_TEST_SCORE);
END LOOP; -- rowStudent_scores
END;

why if block not working within a procedure while comparing two columns of two tables

I need to check whether std_id is present same as in students table if this matches with std_id in std_grace_marks then I need to add that grace_marks of that std_id with marks column in students table.
I have created a procedure and created two cursors to fetch records in loop and I wrote if condition to check whether std_id matches if it is then I am adding marks with grace_marks but if condition is not working here... so please can anyone tell where I am going wrong
My code:
create or replace procedure std_info
IS
CURSOR stdcur IS SELECT std_id,std_name, marks,mark_status FROM students;
CURSOR gracer IS SELECT std_id,grace_marks from student_grace_marks;
myvar stdcur%ROWTYPE;
mycur gracer%ROWTYPE;
BEGIN
OPEN stdcur;
OPEN gracer;
LOOP
FETCH stdcur INTO myvar;
FETCH gracer INTO mycur;
EXIT WHEN stdcur%NOTFOUND;
DBMS_OUTPUT.PUT_LINE( myvar.std_id || ' '|| myvar.std_name||' '||myvar.marks );
if(myvar.std_id=mycur.std_id) then
update students set marks=myvar.marks+mycur.grace_marks;
end if;
END LOOP;
CLOSE stdcur;
CLOSE gracer;
END;
I'm not sure this will ever work. You're fetching a row of each resultset in a row variable, assuming that row 1 for the first resultset will match the std_id of row 1 for the 2nd resultset. There are 2 things wrong with this assumption
There is no ORDER BY clause in the statements, so std_id for the firs row of cursor stdcur could be 10 while std_id for the first row of cursor gracer could be 99. Oracle does not guarantee the order of the a resultset unless an ORDER BY clause is included in the statement.
If table student_grace_marks has more than 1 row, or no rows for a std_id, it will start failing from that row onwards since the count will no longer match.
One solution is to use explicit cursor for loops:
DECLARE
BEGIN
FOR r_student IN (SELECT * FROM students) LOOP
FOR r_student_gm IN (SELECT * FROM student_grace_marks WHERE std_id = r_student.std_id) LOOP
UPDATE students SET marks = marks + r_student_gm.grace_marks WHERE std_id = r_student.std_id;
END LOOP;
END LOOP;
END;
/
.. or .. if you want to use explicit cursors:
In this case the CURSOR gracer will have a where clause to only select the relevant row(s) for that particular student.
Note that I fixed some errors as well
DECLARE
--declare variable to be used in the where clause of the select for cursor gracer.
l_std_id students.std_id%TYPE;
CURSOR stdcur IS SELECT std_id,std_name, marks FROM students;
CURSOR gracer IS SELECT std_id,grace_marks from student_grace_marks WHERE std_id = l_std_id;
myvar stdcur%ROWTYPE;
mycur gracer%ROWTYPE;
BEGIN
OPEN stdcur;
LOOP
FETCH stdcur INTO myvar;
EXIT WHEN stdcur%NOTFOUND;
l_std_id := myvar.std_id;
OPEN gracer;
LOOP
FETCH gracer INTO mycur;
EXIT WHEN gracer%NOTFOUND;
-- use marks, not myvar.marks. If there is >1 record in student_grace_marks it will only add the last value.
-- add the where clause or every update will update all rows and every grace_marks will be added for every student in the table.
UPDATE students set marks= marks+mycur.grace_marks WHERE std_id = l_std_id;
END LOOP;
CLOSE gracer;
END LOOP;
CLOSE stdcur;
END;
/

Oracle cursor with variable columns/tables/criteria

I need to open a cursor while table name, columns and where clause are varying. The table name etc will be passed as parameter. For example
CURSOR batch_cur
IS
SELECT a.col_1, b.col_1
FROM table_1 a inner join table_2 b
ON a.col_2 = b.col_2
WHERE a.col_3 = 123
Here, projected columns, table names, join criteria and where clause will be passed as parameters. Once opened, i need to loop through and process each fetched record.
You need to use dynamic SQL something like this:
procedure dynamic_proc
( p_table_1 varchar2
, p_table_2 varchar2
, p_value number
)
is
batch_cur sys_refcursor;
begin
open batch_cur for
'select a.col_1, b.col_1
from ' || p_table_1 || ' a inner join || ' p_table_2 || ' b
on a.col_2 = b.col_2
where a.col_3 = :bind_value1';
using p_value;
-- Now fetch data from batch_cur...
end;
Note the use of a bind variable for the data value - very important if you will re-use this many times with different values.
From your question i guess you need a dynamic cursor. Oracle provides REFCURSOR for dynamic sql statements. Since your query will be built dynamically you need a refcursor to do that.
create procedure SP_REF_CHECK(v_col1 number,v_col2 date,v_tab1 number,v_var1 char,v_var2 varchar2)
is
Ref_cur is REF CURSOR;
My_cur Ref_cur;
My_type Table_name%rowtype;
stmt varchar2(500);
begin
stmt:='select :1,:2 from :3 where :4=:5';
open My_cur for stmt using v_col1,v_col2,v_tab1,v_var1,v_var2;
loop
fetch My_cur into My_type;
//do some processing //
exit when My_cur%notfound;
end loop;
close My_cur;
end;
Check this link for more http://docs.oracle.com/cd/B10500_01/appdev.920/a96624/11_dynam.htm

Creating a result set (using a select statement ) within a loop

I have created a cursor which returns me a set of rows. While iterating through each of the row, I want to get another result set (by forming a SELECT statement by with a WHERE clause having value from the processed row) from another table. I am a newbie in PLSQL. Can you please guide me on how this could be done? (Can we have a Cursor defined inside the loop while looping for the resultset of the cursor)?
Please excuse me if I am not able to make myself clear.
Thanks in advance
DECLARE
CURSOR receipts IS
SELECT CREATED_T, ACCT_NO, AMT FROM receipt_t
WHERE OBJ_TYPE='misc';
receipts_rec receipts%ROWTYPE;
BEGIN
-- Open the cursor for processing
IF NOT receipts%ISOPEN THEN
OPEN receipts;
END IF;
LOOP
FETCH receipts INTO receipts_rec;
EXIT WHEN receipts%NOTFOUND;
/* Loop through each of row and get the result set from another table */
newQuery := 'SELECT * FROM ageing_data WHERE ACCT_NO = ' || receipts_rec.ACCT_NO;
-- Execute the above query and get the result set, say RS
LOOP
-- For above result set-RS
END LOOP;
END LOOP;
CLOSE receipts;
END;
Yes, you can define a cursor that takes a set of parameters and use those values in the WHERE clause.
DECLARE
CURSOR c_cursor1 IS
SELECT field1, field2, ... , fieldN
FROM table1
WHERE conditions;
CURSOR c_cursor2 (p_parameter NUMBER) IS
SELECT field1, field2, ..., fieldN
FROM table2
WHERE table2.field1 = p_parameter;
BEGIN
FOR record1 IN c_cursor1 LOOP
FOR record2 IN c_cursor2(record1.field1) LOOP
dbms_output.put_line('cursor 2: ' || record2.field1);
END LOOP
END LOOP;
END;
Yes, you can do that, but there is absolutely no reason to. Try the following:
BEGIN
FOR aRow IN (SELECT rt.CREATED_T, rt.ACCT_NO, rt.AMT, ad.*
FROM RECEIPT_T rt
INNER JOIN AGEING_DATA ad
ON (ad.ACCT_NO = rt.ACCT_NO)
WHERE rt.OBJ_TYPE='misc')
LOOP
-- Process the data in aRow here
END LOOP;
END;
This does exactly the same work as the original "loop-in-a-loop" structure but uses the database to join the tables together on the common criteria instead of opening and closing cursors multiple times.
Share and enjoy.
Something like this can be done in the following manner:
DECLARE
CURSOR cursor1 IS
SELECT *
FROM table1;
CURSOR cursor2 IS
SELECT *
FROM table2
WHERE column1 = I_input_param;
BEGIN
FOR table_1_rec in cursor1 LOOP
I_input_param := table_1_rec.column_1;
FOR table_2_rec in cursor2 LOOP
....
....
END LOOP;
END LOOP;
END;
I have used an implicit open/fetch here. I hope you get the idea.

How to find number of rows in cursor

I would like to find the number of rows in a cursor. Is there a keyword that can help? Using COUNT, we have to write a query. Any help will be greatly appreciated.
The cursor_variable.%ROWCOUNT is the solution. But its value will be 0 if you check it after opening. You need to loop through all the records, to get the total row count. Example below:
DECLARE
cur sys_refcursor;
cur_rec YOUR_TABLE%rowtype;
BEGIN
OPEN cur FOR
SELECT * FROM YOUR_TABLE;
dbms_output.put_line(cur%rowcount);--returning 0
LOOP
FETCH cur INTO cur_rec;
EXIT WHEN cur%notfound;
dbms_output.put_line(cur%rowcount);--will return row number beginning with 1
dbms_output.put_line(cur_rec.SOME_COLUMN);
END LOOP;
dbms_output.put_line('Total Rows: ' || cur%rowcount);--here you will get total row count
END;
/
You must open the cursor and then fetch and count every row. Nothing else will work.
You can also use BULK COLLECT so that a LOOP is not needed,
DECLARE
CURSOR c
IS SELECT *
FROM employee;
TYPE emp_tab IS TABLE OF c%ROWTYPE INDEX BY BINARY_INTEGER;
v_emp_tab emp_tab;
BEGIN
OPEN c;
FETCH c BULK COLLECT INTO v_emp_tab;
DBMS_OUTPUT.PUT_LINE(v_emp_tab.COUNT);
CLOSE c;
END;
/
Edit: changed employee%ROWTYPE to c%ROWTYPE
You can use following simple single line code to print cursor count
dbms_output.put_line(TO_CHAR(cur%rowcount));
This should work for you
DECLARE
CURSOR get_data_ IS
SELECT *
FROM table_abc_
WHERE owner = user_; -- your query
counter_ NUMBER:= 0;
BEGIN
FOR data_ IN get_data_ LOOP
counter_ := counter_ + 1;
END LOOP;
dbms_output.put_line (counter_);
END;
DECLARE #STRVALUE NVARCHAR(MAX),
#CREATEDDATE DATETIME,
#STANTANCEVALUE NVARCHAR(MAX),
#COUNT INT=0,
#JOBCODE NVARCHAR(50)='JOB00123654',
#DATE DATETIME=GETDATE(),
#NAME NVARCHAR(50)='Ramkumar',
#JOBID INT;
CREATE TABLE #TempContentSplitValue (ITEMS NVARCHAR(200))
SELECT #JOBID = i.Id FROM JobHeader_TBL i WHERE Id=1201;
IF EXISTS (SELECT 1 FROM JobHeader_TBL WHERE Id=#JOBID)
BEGIN
SELECT #STRVALUE= Description from ContentTemplate_TBL where Id=1
INSERT INTO #TempContentSplitValue SELECT * FROM dbo.split(#STRVALUE, '_')
SET #STRVALUE=''
DECLARE db_contentcursor CURSOR FOR SELECT ITEMS FROM #TempContentSplitValue
OPEN db_contentcursor
FETCH NEXT FROM db_contentcursor
INTO #STANTANCEVALUE
WHILE (##FETCH_STATUS = 0)
BEGIN
SET #STRVALUE += #STANTANCEVALUE + 'JOB00123654'
SET #COUNT += 1
SELECT #COUNT
FETCH NEXT FROM db_contentcursor INTO #STANTANCEVALUE
END
CLOSE db_contentcursor
DEALLOCATE db_contentcursor
DROP TABLE #TempContentSplitValue
SELECT #STRVALUE
END
Here I am trying to count the total number of customers with age greater than 25. So store the result in the cursor first. Then count the size of the cursor inside the function or in the main begin itself.
DECLARE
cname customer24.cust_name%type;
count1 integer :=0;
CURSOR MORETHAN is
SELECT cust_name
FROM customer24
where age>25;
BEGIN
OPEN MORETHAN;
LOOP
FETCH MORETHAN into cname;
count1:=count1+1;
EXIT WHEN MORETHAN%notfound;
END LOOP;
-- dbms_output.put_line(count1);
dbms_output.put_line(MORETHAN%ROWCOUNT);
CLOSE MORETHAN;
END;
There is a possible work around that may be useful/needed because of the overhead of accessing a database server over a network (e.g., when using Ajax calls)
Consider this:
CURSOR c_data IS
SELECT per_first_name , null my_person_count
FROM person
UNION
SELECT null as per_first_name , count( distinct per_id ) as my_person_count
FROM person
order by my_person_count ;
The first row fetched has the count of records. One MUST add specific columns fetched (the use of the * does not work), and one can add additional filters.
Try this:
print(len(list(cursor)))
I always read that people loop through results. Why not using a count(*)?
An example from my production code:
PROCEDURE DeleteStuff___(paras_ IN Parameters_Type_Rec)
IS
CURSOR findEntries_ IS
select * from MyTable
where order_no = paras_.order_no;
counter_ NUMBER;
CURSOR findEntries_count_ IS
SELECT COUNT(*) from MyTable
where order_no = paras_.order_no;
BEGIN
OPEN findEntries_count_;
FETCH findEntries_count_ INTO counter_;
CLOSE findEntries_count_;
dbms_output.put_line('total records found: '||counter_);
IF (counter_ = 0) THEN
-- log and leave procedure
RETURN;
END IF;
FOR order_rec_ IN findEntries_ LOOP
EXIT WHEN findEntries_%NOTFOUND OR findEntries_%NOTFOUND IS NULL;
-- do stuff - i.e. delete a record.
API_Package.Delete(order_rec_);
END LOOP;
END DeleteStuff___;
If the query is small, that is my prefered way.
In this example, I just want to know (and log) how many entries I'll delete.
p.s. Ignore the three underlines. In IFS, this is used when you want private procedures or functions.
You can’t have cursor count at start. For that you need to fetch complete cursor; that is the way get cursor count.
declare
cursor c2 is select * from dept;
var c2%rowtype;
i number :=0;
begin
open c2;
loop
fetch c2 into var;
exit when c2%NOTFOUND;
i: = i+1;
end loop;
close c2;
dbms_output.put_line('total records in cursor'||i);
end;
You can use %ROWCOUNT attribute of a cursor.
e.g:
DECLARE
CURSOR lcCursor IS
SELECT *
FROM DUAL;
BEGIN
OPEN lcCursor ;
DBMS_OUTPUT.PUT_LINE(lcCursor%ROWCOUNT);
CLOSE lcCursor ;
END;

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