I am currently learning pl/sql using oracle 10g
I have a certain confusion
When should I use stored procedures and when should i go for functions?
Please help me out with some real world example.
Thank you.
A function returns a value, although that could actually be an object like a cursor.
Also only a function can be defined with the following (as of 11.1):
DETERMINISTIC option, which helps the optimizer avoid redundant function calls.
PARALLEL_ENABLED option, which allows the function to be used safely in slave sessions of parallel DML evaluations.
PIPELINED option, which returns the results of a table function iteratively.
RESULT_CACHE option, which stores function results in the PL/SQL function result cache.
RESULT_CACHE clause, which specifies the data sources on which the results of a function.
So if you need to return multiple values, use a procedure. However be aware that the above five features are then not available.
If you want to include a PL/SQL subprogram in a SQL statement then you probably want a function.
http://docs.oracle.com/cd/B28359_01/appdev.111/b28370/subprograms.htm#CHDBEJGF
DECLARE
l_user_id VARCHAR2(1);
l_received_user VARCHAR2(30);
PROCEDURE print_user_name(user_name_in IN VARCHAR2)
AS
BEGIN
DBMS_OUTPUT.PUT_LINE('The user''s name is: ' || INITCAP(user_name_in));
END print_user_name;
FUNCTION get_user_name(user_id_in IN VARCHAR2) RETURN VARCHAR2
AS
l_user_name VARCHAR2(30);
BEGIN
SELECT 'Amanda'
INTO l_user_name
FROM dual
WHERE dummy = user_id_in;
RETURN l_user_name;
END get_user_name;
BEGIN
-- excute an action --
print_user_name('John');
l_user_id := 'X';
-- hold action's result in a variable --
l_received_user := get_user_name(l_user_id);
-- work with the received result/variable --
DBMS_OUTPUT.PUT_LINE('The received user''s name is: ' || INITCAP(l_received_user));
IF l_received_user = 'John' THEN
DBMS_OUTPUT.PUT_LINE('The received user''s name is John');
ELSE
DBMS_OUTPUT.PUT_LINE('The received user''s name is not John');
END IF;
END;
/*
The user's name is: John
The received user's name is: Amanda
The received user's name is not John
*/
Difference is that sored procedure do something, while functions do something and return result (variable or table).
Related
This is the code:
CREATE PROCEDURE print_string(IN input_string VARCHAR(255))
BEGIN
DECLARE num_chars INT DEFAULT 0;
IF input_string IS NULL THEN
SET num_chars = 0;
ELSE
SET num_chars = CHAR_LENGTH(input_string);
END IF;
SELECT UPPER(input_string), num_chars;
END;
I get error:
PLS-00103: Encountered the symbol "IN" when expecting one of the following: <an identifier> <a double-quoted delimited-identifier>
current delete exists prior
Errors: check compiler log
How do I fix: current delete exists prior?
The immediate error is that you have the argument name and mode the wrong way around - it should be (input_string IN ... not (IN input_string .... But there are other problems:
Oracle recommends VARCHAR2 over VARCHAR.
arguments just have the data type, not a size (or precision/scale), so it should be (input_string IN VARCHAR2) not (input_string IN VARCHAR2(255).
you are missing the IS/AS keyword.
DECLARE comes before BEGIN in a PL/SQL block; having a nested block here would be valid, but you're missing a BEGIN and END; if you do that, and it isn't necessary so I don't think it's what you meant. And you don't need the DECLARE at all for a procedure, it's implied.
if you want a default value for a PL/SQL variable then assign it, rather than using DEFAULT. (You don't really need to do this here, as you always assign a value later anyway, but I'm sticking with your general approach.)
it's probably better to use native Oracle types, so NUMBER or PLS_INTEGER instead of INT.
assignment of values is with :=, not SET ... = ....
CHAR_LENGTH should just be LENGTH (unless you have your own function with that name).
in PL/SQL you have to select into something, and from something. But if you do that here, you still have to return it to the caller somehow.
given that you want to 'print' the string, you probably want dbms_output - though that relies on the client showing the result, which most don't by default, and it's generally only used for debugging...
So this would work:
CREATE PROCEDURE print_string(input_string IN VARCHAR2) AS
num_chars PLS_INTEGER := 0;
BEGIN
IF input_string IS NULL THEN
num_chars := 0;
ELSE
num_chars := LENGTH(input_string);
END IF;
DBMS_OUTPUT.PUT_LINE(UPPER(input_string) || ': ' || num_chars);
END;
/
BEGIN
DBMS_OUTPUT.ENABLE;
print_string('This is a test');
END;
/
1 rows affected
dbms_output:
THIS IS A TEST: 14
fiddle
But again, dbms_output isn't ideal. And it could be done much more simply (#Mto has shown one way), or without using PL/SQL at all.
You can fix the issues (listing in #Alex Poole's answer) and simplify the procedure to:
CREATE PROCEDURE print_string(
input_string IN VARCHAR2
)
IS
BEGIN
DBMS_OUTPUT.PUT_LINE(UPPER(input_string) || ', ' || COALESCE(LENGTH(input_string), 0));
END;
/
Then:
BEGIN
DBMS_OUTPUT.ENABLE;
print_string('This is a test');
print_string(NULL);
END;
/
Outputs:
THIS IS A TEST, 14
, 0
fiddle
The code syntax is incorrect here. It should be something like
CREATE OR REPLACE PROCEDURE print_string(input_string IN VARCHAR2)
IS
BEGIN
I have a stored procedure which I want to return cursor as the OUT parameter. I see the output in
dbms_output.put_line(as_return_val); like
Loan Purpose can not be Limited || /loanPurpose
THE PURPOSE OF PURCHASE IS NOT VALID || /loanPurpose
I need to read this response as a array of Objects(each ro one Object) in my service layer. Sorry I am not sure I need to send it as a cursor or like a varchar from here. I added as_return_val this variable to see whether I am getting correct response .
Procedure
create or replace PROCEDURE PR_LOGIC_CHECK_TEST
(in_loan_id IN NUMBER,
in_trans_id IN NUMBER)AS
BEGIN
DECLARE
as_errm VARCHAR2(2000);
curr_cursor_out SYS_REFCURSOR;
temp_cursor_row temp_cor_ll_cursor%rowtype;
as_return_val VARCHAR2(500);
BEGIN
pr_loan_logic_check(in_loan_id, in_trans_id, as_errm, curr_cursor_out);
LOOP
FETCH curr_cursor_out INTO temp_cursor_row;
EXIT WHEN curr_cursor_out%notfound;
as_return_val := temp_cursor_row.ret_value
|| ' || '
|| '/'||temp_cursor_row.xpath_name;
--dbms_output.put_line(as_return_val);
END LOOP;
close curr_cursor_out;
ROLLBACK;
END;
END PR_LOGIC_CHECK_TEST;
I'm still guessing at what you really want to happen since you haven't actually given us a reproducible test case (i.e. something that we can run locally or on dbfiddle or liveSQL that produces a particular output given a particular input).
Architecturally, it seems problematic to have a stored procedure whose only purpose is to format the output of a different procedure for human consumption. Formatting results would more properly be done in the display layer (the view of an MVC application but view means something else when we're talking about databases so I'm using "display layer") of the application not in a stored procedure. It would make more sense for your application to call pr_loan_logic_check directly and to let your display layer decide to concatenate the values from multiple columns together. If someone wants to change how the output is formatted later, you'd then just be changing code in the display layer not in your backend database.
My guess is that you want to return a collection like this. Note that I'm creating the collection type at the SQL level. You could create it in a PL/SQL package as well.
create or replace type varchar2_tbl
is table of varchar2(500);
create or replace PROCEDURE PR_LOGIC_CHECK_TEST (
in_loan_id IN NUMBER,
in_trans_id IN NUMBER,
out_strings OUT varchar2_tbl
)
AS
as_errm VARCHAR2(2000);
curr_cursor_out SYS_REFCURSOR;
temp_cursor_row temp_cor_ll_cursor%rowtype;
BEGIN
pr_loan_logic_check(in_loan_id, in_trans_id, as_errm, curr_cursor_out);
out_strings := out_strings();
LOOP
FETCH curr_cursor_out INTO temp_cursor_row;
EXIT WHEN curr_cursor_out%notfound;
out_strings.extend();
out_strings( out_strings.count ) :=
temp_cursor_row.ret_value
|| ' || '
|| '/'||temp_cursor_row.xpath_name;
END LOOP;
close curr_cursor_out;
-- I have trouble imagining why you'd put a `rollback` here
ROLLBACK;
END PR_LOGIC_CHECK_TEST;
What would be the PL/SQL equivalent of this SQL query:
SELECT * FROM table(OWNER.PACKAGE.get_exam('123456789'));
This is the Function that I am trying to call:
FUNCTION get_exam(id IN VARCHAR2)
RETURN ab_assign_v1
IS
CURSOR c_exams(cid VARCHAR2) IS
SELECT t_api_exam_v1(
sei.person_id, --unique id
l.description --loc description
)
FROM my_view sei
JOIN loc l
ON sei.loc_code = l.loc_code
v_collection ab_assign_v1;
BEGIN
OPEN c_exams(id);
FETCH c_exams BULK COLLECT INTO v_collection;
CLOSE c_exams;
RETURN v_collection;
EXCEPTION
WHEN OTHERS THEN
error_a1.raise_error(SQLCODE, SQLERRM);
END get_exam;
Hope this helps.
DECLARE
lv <COLLECTION_NAME>;
BEGIN
lv:= OWNER.PACKAGE.get_exam('123456789');
dbms_output.put_line(lv.COUNT);
END;
/
Assuming that you want to return the result of a function :
select owner.package.get_exam('123456789') from table
Your function returns a nested table type. You simply need to declare a variable of that type, and assign to it as you would if it were a scalar:
declare
l_coll your_collection_type;
begin
l_coll := OWNER.PACKAGE.get_exam('123456789');
end;
/
In this example your_collection_type is a placeholder for whatever object your function actually returns.
" I am getting this error: PLS-00201: identifier 'ab_assign_v1' must be declared "
ab_assign_v1 is the type used by your function. From the code posted in your revised question it seems that type is in the same schema which owns the package with the function. However your original pseudo-code prefixes the call with the schema name. So, putting two and two together, you need to revise the variable declaration to include the schema too. (You may need to grant EXECUTE on it too, if you haven't done this already).
declare
l_coll OWNER.ab_assign_v1;
begin
l_coll := OWNER.PACKAGE.get_exam('123456789');
end;
/
I am familiar with MSSQL and using a parameter within the query, but I am not sure how I would do this within PL/SQL.
DECLARE
LSITEID NUMBER := 100001;
BEGIN
SELECT * from invoicehead ih
JOIN sitemaster sm on sm.SITEIID = ih.SITEIID
JOIN invoiceline il on il.invoiceIID = ih.invoiceIID
WHERE
ih.StartDate BETWEEN '2015-12-01' AND '2016-03-07'
AND SITEIID IN ( LSITEID)
END;
Right now I am testing this within Pl/SQL. But essentially I would be passing in the query with the parameter from MSSQL Linked Server OPENQuery.
How I can run the above query in PL/SQL with the parameter?
There is plenty of other resource for finding an answer, e.g. here (Tutorialspoint) or specifically here (plsql-tutorial). But perhaps I have missed your point.
To not remain on merely citing links, your query could look like this:
DECLARE
LSITEID integer;
BEGIN
LSITEID := 100001;
-- dostuff
END;
Two things to note: First, in a declare part (as I have learnt it) you should avoid assigning values. Second, if you intend to pass in different parameters you could/should use a procedure.
In PL/SQL you just use the name of the argument. In the following example, the argument is P_VALUE, note select statement says where dummy = p_value.
DECLARE
FUNCTION dummycount (p_value IN DUAL.dummy%TYPE)
RETURN INTEGER
AS
l_ret INTEGER;
BEGIN
SELECT COUNT (*) c
INTO l_ret
FROM DUAL
WHERE dummy = p_value;
RETURN l_ret;
END dummycount;
BEGIN
DBMS_OUTPUT.put_line ('A: ' || dummycount (p_value => 'A'));
DBMS_OUTPUT.put_line ('X: ' || dummycount (p_value => 'X'));
END;
This results in the following output:
A: 0
X: 1
I have an existing Customers table and want to output each row from this table using a stored procedure. There is no input criteria, just need to output all of the records.
The stored procedure should basically be equivalent to:
"SELECT C_ID, LAST, FIRST, DOB, DPHONE, EMAIL FROM customers;"
This seems simple but I can't figure it out. All my searches haven't worked out for this case.
How would one accomplish this?
EDIT: Answered my question below. Very simple.
In Oracle your options are:
1. Use a function and return a REF CURSOR
2. Use a procedure and use a REF CURSOR as an OUT parameter
3. Use a PIPELINED function
4. Use a function and return a collection.
read this documentation
Overview of Table Functions
see similar question here Return collection from packaged function for use in select
simple sample of such function
CREATE FUNCTION StockPivot(p refcur_pkg.refcur_t) RETURN TickerTypeSet
PIPELINED IS
out_rec TickerType := TickerType(NULL,NULL,NULL);
in_rec p%ROWTYPE;
BEGIN
LOOP
FETCH p INTO in_rec;
EXIT WHEN p%NOTFOUND;
-- first row
out_rec.ticker := in_rec.Ticker;
out_rec.PriceType := 'O';
out_rec.price := in_rec.OpenPrice;
PIPE ROW(out_rec);
-- second row
out_rec.PriceType := 'C';
out_rec.Price := in_rec.ClosePrice;
PIPE ROW(out_rec);
END LOOP;
CLOSE p;
RETURN;
END;
/
Nevermind! Just got it. It is pretty simple. I just did this:
CREATE OR REPLACE PROCEDURE CustomerReport AS
BEGIN
FOR cus IN (SELECT C_ID, LAST, FIRST, DOB, DPHONE, EMAIL FROM customers)
LOOP
dbms_output.put_line(cus.C_ID||' '||cus.FIRST||' '||cus.LAST||' '||cus.DOB||' '||cus.DPHONE||' '||cus.EMAIL);
END LOOP;
END;