How to include a huge SQL statement into UTL_FILE procedure? - plsql

I wrote a procedure using UTL_FILE:
CREATE OR REPLACE PROCEDURE UTL_CREATE_FILE
(
output_file in UTL_FILE.file_type,
log_file in UTL_FILE.file_type,
filename in VARCHAR2 (64),
ddate in VARCHAR2 (19),
sep in NVARCHAR2 (3)
)
IS
BEGIN
sep := Chr(9);
ddate := TO_CHAR (SYSDATE, 'YYYYMMDD');
filename := 'EXT' || ddate || '.dat';
output_file := UTL_FILE.fopen ('C:/home/S/', filename, 'w', 32000);
log_file := UTL_FILE.fopen ('C:/home/S/', 'WEEKLY.log', 'a', 32000);
UTL_FILE.put_line (log_file, TO_CHAR (SYSDATE, 'DD-MM-YYYY HH24:MI:SS') || 'Started with file ' || filename);
select 'HUGE SQL STATEMENT'|| sep || 'Anykey' as OUTLINE from DUAL;
UTL_FILE.put_line (output_file, OUTLINE);
UTL_FILE.fclose (output_file);
UTL_FILE.put_line (log_file, TO_CHAR (SYSDATE, 'DD-MM-YYYY HH24:MI:SS') || 'Finished for file ' || filename);
UTL_FILE.fclose (log_file);
END;
But Toad returns Warning: compiled but with compilation errors.
Could anybody help me?
As a result I would like to receive a EXT.DAT (and logs) in C:/home/S/ directory. Thank you in advance.

TOAD should give you the compilation errors - they are probably on a separate tab (it's been a while since I used that particular IDE).
However, it easy to spot one bloomer: we cannot assign values to parameters defined in IN mode. The purpose of such parameters is that the calling program assigns their values.
However, in this case I think you need to assign ddate and filename, so you should move them out of the procedure's signature and into its declaration section.
sep I would keep as a parameter but give it a default value.
Bear in mind that SQL limits us to 4000 characters in a column . So if 'HUGE SQL STATEMENT' exceeds 3993 characters your code will hurl a runtime error.
If you're making these sorts of errors you're probably not up-to-speed with the intricacies of writing files from PL/SQL. I suggest you read this previous answer of mine and also this one regarding this topic.

You should be able to append this to the end of your script to get the errors (I don't use TOAD, but I'd expect it to support it). It goes after the last end;.
/
show errors;
The compilation errors that stand out to me -
The parameters are being assigned to. This is illegal as "in" parameters. They don't seem to be used for input, so they should probably be removed from the signature. If this is a code snippet and they do provi

Related

PL/SQL if then else statements not running

I have written following code in oracle pl/sql
create or replace procedure sorting_criteria(criteria in varchar)
as
begin
if(criteria='lowest price')
then
declare
p_name product.p_name%type;
cursor ptr is select p_name from product order by amount ASC;
begin
open ptr;
loop
fetch ptr into p_name;
exit when ptr%notfound;
dbms_output.put_line(p_name);
end loop;
close ptr;
end;
else if(criteria='highest price')
then
declare
p_name product.p_name%type;
cursor ptr is select p_name from product order by amount DESC;
begin
open ptr;
loop
fetch ptr into p_name;
exit when ptr%notfound;
dbms_output.put_line(p_name);
end loop;
close ptr;
end;
else
dbms_output.put_line('Enter valid criteria!');
end if;
end;
/
But it is giving following error: Error at line 35: PLS-00103: Encountered the symbol ";" when expecting one of the following: Please help
The ELSE-IF statement in PL/SQL has to be written as ELSIF. Otherwise, you should close the second IF with an other END IF; statement.
You can solve the issue by changing the ELSE IF at line 17 to an ELSIF
The answer by #GregorioPalamà correctly addresses your issues. But you can drastically reduce the workload by changing your thinking away from "If...then...else" to the "set of" and letting SQL do the work. In this case the only difference is sorting either ascending or descending on amount. The same effect can be achieved by sorting ascending on amount or minus amount; and SQL can make that decision. So you can reduce the procedure to validating the parameter and a single cursor for loop:
create or replace procedure sorting_criteria(criteria in varchar2)
as
cursor ptr(c_sort_criteria varchar2) is
select p_name
from product
order by case when c_sort_criteria = 'lowest price'
then amount
else -amount
end ;
begin
if criteria in ('lowest price', 'highest price')
then
for rec in ptr(criteria)
loop
dbms_output.put_line('Product: ' || rec.p_name );
end loop;
else
dbms_output.put_line('Enter valid criteria!');
end if;
end sorting_criteria;
/
See demo here. For demonstration purposed I added the amount to the dbms_output.
A couple notes:
While it is not incorrect using p_... as a column name, it is also
not a good idea. A very common convention (perhaps almost a
standard) to use p_... to indicate parameters. This easily leads to
confusion; confusion amongst developers is a bad thing.
IMHO it is a bug to name a local variable the same as a table
column name. While the compiler has scoping rules which one to use
it again leads to confusion. The statement "where table.name = name"
is always true, except when at least one of them is null, which possible could lead to updating/deleting every row in your table. In this
case p_name is both a column and a local variable.

Oracle APEX: Execute immediate on collection

I have the following code:
declare
y pls_integer := 0;
v_msg varchar2(4000);
plsql varchar(4000);
begin
if not apex_collection.collection_exists(p_collection_name=>'P16_COLLECTION') then
wwv_flow.debug('No Apex collection found!');
else
for x in (select * from apex_collections where collection_name = 'P16_COLLECTION' and seq_id > 1 order by seq_id)
loop
y := y+1;
FOR i IN 1..25
LOOP
plsql := 'begin apex_collection.update_member_attribute (p_collection_name=> ''P16_COLLECTION'', p_seq=>' || TO_CHAR(x.seq_id) || ',p_attr_number =>' || TO_CHAR(i) || ',p_attr_value=>wwv_flow.g_f' || TO_CHAR(i, 'FM00') || '(' || TO_CHAR(y) || ')); end;';
wwv_flow.debug(plsql);
EXECUTE IMMEDIATE plsql;
END LOOP;
end loop;
end if;
exception when others then
v_msg := ''||sqlerrm;
wwv_flow.debug('ERR: '||v_msg);
end;
This code is very similar to the one proposed here, but I loop through 25 columns. The issue with Oracle Apex is the max number of chars PL/SQL is allowed to have, so I am unable to just write 25 update_member_attribute - calls.
But instead of a it excecuting I get an error no data found.
I triple checked that the collection P16_COLLECTION exists.
The issue with Oracle Apex is the max number of chars PL/SQL is allowed to have
I'm not sure I understood this statement. It is PL/SQL you use. You declared a local PLSQL variable as VARCHAR2(4000). Why didn't you specify its max allowed size, 32767? Would that help?
Furthermore, saying that you got NO-DATA-FOUND exception: are you sure that this piece of code raised it? Because, there's no SELECT statement in there ... the one you used in a cursor FOR loop can't raise NO-DATA-FOUND; UPDATE either. Therefore, it must be something else, I presume.
Enable DEBUG, run the page and - when you get the error - view debug results and locate the culprit.

Using CLOB instead of VARCHAR2

We want to create an XML. The current code does it by appending one XML tag at a time to a VARCHAR2 variable.
xmlString VARCHAR2(32767);
....
....
xmlString := xmlString || '<' || elementName || '>' || elementValue || '</' || elementName || '>';
However due to size limitation of 32767 characters on VARCHAR2, we get the following error for a very long XML.
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
The solution we have is to declare a CLOB and write a procedure to keep flushing the VARCHAR2 variable to the CLOB.
v_result clob;
.....
.....
IF xmlString IS NOT NULL THEN
dbms_lob.writeappend( v_result, LENGTH(xmlString), xmlString);
xmlString := NULL;
END IF;
However this would require replacing lots of exiting code lines with calls to the new function. Is there a better way to do this?
Anything similar to Operator Overloading in PLSQL? Can I change the data type of xmlString variable to CLOB and make the || operator to do the work of dbms_lob.writeappend?
Yes, if you change the data type of xmlString to clob, the string concatenation operator will continue to work.
However, building XML this way would be a very poor architecture. That's the sort of architecture that has a high probability of generating invalid XML when, for example, one of the strings happens to have a character that needs to be escaped (or for any of a number of different reasons). Oracle provides a whole host of functions to generate XML (XMLElement, XMLForest, SYS_XMLGen, DBMS_XMLQuery, etc. depending on your use case). It would be far better architecturally to use those built-in functions.

Assign value to a field of rowtype where `field name` is a string

I want to assign a value to a rowtype's field but I don't know how to do it.
Suppose that I have a table X inside my database.
Suppose also that I have the following variables
a ( X%ROWTYPE ), representing a row of the table X
b ( VARCHAR2 ), containing a column name of the table X
c ( VARCHAR2 ), containing what I want to store inside a.b
What I want to do : something like a.b := c.
I've come up with something like this :
EXECUTE IMMEDIATE 'SELECT '|| c || ' INTO a.' || b || ' FROM DUAL';
Apparently, this isn't the right way to go. I get a ORA-0095: missing keyword error.
Can anyone help me with this ?
Here is the complete code :
DECLARE
tRow MyTable%ROWTYPE;
col_name VARCHAR(10) := 'Length';
nValue NUMBER(12,4) := 0.001;
dynamic_request VARCHAR(300);
BEGIN
dynamic_request := 'SELECT '|| nValue || ' INTO tRow.' || col_name || ' FROM DUAL';
EXECUTE IMMEDIATE dynamic_request;
END;
Ok, I solved it !
Short answer : Using a global variable does the trick
Answer Development
Let us consider two facts about dynamic PL/SQL blocks (i.e., PL/SQL blocks written as strings, to be executed trough an EXECUTE IMMEDIATE statement)
[1] There is no such thing as variable scope when you create a dynamic PLSQL block. What I mean by that is, if you do something like this :
CREATE OR REPLACE PROCEDURE DynamicVariableAssignment(
theString IN VARCHAR2
)
IS
BEGIN
EXECUTE IMMEDIATE 'BEGIN theString := ''test''; END; ';
END;
it will simply not work because the scope of theString is not transfered to the dynamic PL/SQL block. In other words, the dynamic PL/SQL block doesn't "inherit" of any variable, wherever it is executed.
[2] You might say "OK, no panic, I can give input/output arguments to my dynamic PL/SQL block, right ?". Sure you can, but guess what : you can only give SQL types as in/out ! True PL/SQL types on the other hand, such as a myTable%rowtype, are not accepted as an input for a dynamic PL/SQL block. So the answer of hmmftg won't work either :
-- I've reduced the code to the interesting part
dynamic_request := 'BEGIN :t_row.' || col_name || ':= 0.001; END;';
EXECUTE IMMEDIATE dynamic_request USING IN OUT tRow;
-- (where tRow is of type myTable%ROWTYPE)
since tRow is of MyTable%ROWTYPE, it is not a valid SQL type and is therefore not valid as an input to the dynamic PL/SQL block.
The Solution Who would have thought that global variables would come and save the day ? As we said in [1], we have no reference to any variable outside the dynamic PL/SQL block. BUT we can still access global variables defined in package headers !
Let us assume that I have a package kingPackage in which I define the following :
tempVariable myTable%ROWTYPE;
Then I can do this :
FINAL CODE (body only)
-- Copy tRow into temp variable
kingPackage.tempVariable := tRow;
-- We modify the column of the temp variable
vString := 'BEGIN kingPackage.tempVariable.' || col_val || ' := ' || TO_CHAR(vNumber) ||'; END;';
EXECUTE IMMEDIATE vString;
-- The column value has been updated \o/
tRow := kingPackage.tempVariable;
There you go, fellas !
Have a nice day
try this:
CREATE OR REPLACE PROCEDURE ROW_CHANGER(
tRow IN MyTable%ROWTYPE,
col_name IN VARCHAR,
nValue IN NUMBER)
AS
dynamic_request VARCHAR(300);
BEGIN
dynamic_request := 'BEGIN :t_row.'||COL_NAME ||':= :n_value; END;';
EXECUTE IMMEDIATE dynamic_request
USING IN OUT TROW, IN nValue;
END;
this is because in your EXECUTE IMMEDIATE the tRow MyTable%ROWTYPE is not defined,
so we defined it with using statement.

Looking for a utility that converts a SQL statement into a dynamic SQL statement

I am looking for a utility that will convert Oracle SQL to a string that can executed dynamically.
Edit:
Yes, consider this simple SQL
SELECT * FROM TABLE
WHERE COLUMN_NAME = 'VALUE'
I have a utility which for T-SQL which converts the above SQL to a synamic SQL as follows:
BEGIN
DECLARE #Exe_String VarChar(2000)
DECLARE #Qt Char(1)
DECLARE #Cr Char(1)
SET #Qt = Char(39)
SET #Cr = Char(10)
SET #Exe_String = 'SELECT * FROM TABLE ' + #Cr
SET #Exe_String = #Exe_String + 'WHERE COLUMN_NAME = ' + #Qt + 'VALUE' + #Qt + '' + #Cr
PRINT #Exe_String
--Execute (#Exe_String)
END
Granted that the code generated good probably be better, yo get the idea, I hope.
I'm looking for the same type of conversion for Oracle SQL.
Here is a tool that I have used a couple of times. You will have to change the output a little to get it to run but it sure beats having to figure out how to escape all the single ticks.
Sql Tuning
After you click on the link it will take you right to the site and a page with sample SQL. Click the "Static SQL to Dynamic SQL" button and you can see how it works. Then input your own sql you want converted and click the button again. Remove the extra tick (') marks in the end and beginning of each line with the exception of the first and last line and pipes (|) don't need to be there either. Hope this helps.
As a raw translation of your T-SQL to PL/SQL
DECLARE
Exe_String VarChar(2000);
Qt CONSTANT Char(1) := CHR(39);
Cr CONSTANT Char(1) := CHR(10);
BEGIN
exe_string := 'SELECT * FROM TABLE '||Cr;
exe_string := exe_string ||
'WHERE COLUMN_NAME = ' || Qt || 'VALUE' ||Qt || '' ||Cr;
dbms_output.put_line(exe_string);
--
EXECUTE IMMEDIATE exe_string;
END;
The obvious difference is that in Oracle the concatenation operator for strings is || rather than +.
Personally, I have a little string manipluation package (let's call it pstring) that I'd use in a case like this - includes functions like enquote(string), standard constants for newline,tab,etc and the ability to do C-style text replacement.
exe_string :=
pstring.substitute_text('SELECT * FROM %s \n WHERE %s = %s',
table_name,column_name,pstring.enquote(value));
Have you considered using bind variables - i.e. :value - rather than dealing with escaping all the internal quotes? It's a good defence against SQL injection.
Obviously there's some difficulty if you have varying numbers of variables (you need to use DBMS_SQL to link them to the statement rather than a simple EXECUTE IMMEDIATE) but for your simple case it would look like this.
PROCEDURE (table_name IN VARCHAR2, column_name IN VARCHAR2)
IS
Exe_String VarChar(2000);
BEGIN
exe_string :=
pstring.substitute_text('SELECT * FROM %s \n WHERE %s = :value',
table_name,column_name);
dbms_output.put_line(exe_string);
--
EXECUTE IMMEDIATE exe_string USING pstring.enquote(value);
END;
Although of course you have to do something with the results of your SQL.
EXECUTE IMMEDIATE exe_string INTO lresult USING pstring.enquote(value);
Which is difficult when the shape of the table may differ - again, you have to look at Type 4 dynamic SQL (DBMS_SQL).

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