I have this homework assignment :
Write an anonymous PL/SQL block that accepts a string as input and removes all of the vowels (a.e.i.o.u) from the string, then outputs the results.
The output should look like this:
Run the Program
SQL>#rm_vowels
Enter the String: A penny for your thoughts
SQL>****************************
SQL>The new string is: pnny fr yr thghts
And this does look like something really easy to do but I'm really lacking some PL/SQL experience to get this done.
From my searches so far I've realized I need to use something similar to this :
REGEXP_REPLACE(name,'[a,e,i,o,u,A,E,I,O,U]','')
Right ?
You can also use the translate function, which might be marginally faster than regexp_replace:
select translate('A penny for your thoughts', 'xaeiouAEIOU', 'x') new_str from dual;
NEW_STR
------------------
pnny fr yr thghts
You may wish to put a trim around to remove any leading/trailing spaces.
Technically, the assignment calls for an anonymous pl/sql block, and prompting user for input. So you'd have something like this:
set serveroutput on
set verify off
accept vstring prompt "Please enter your string: ";
declare
vnewstring varchar2(100);
begin
vnewstring := regexp_replace('&vstring', '[aeiouAEIOU]','');
dbms_output.put_line('The new string is: ' || vnewstring);
end;
/
You can put this in a file called "my_homework_from_SO.sql" and from the same directory the file is located, login to sqlplus and run it:
#my_homework_from_SO.sql
Please enter your string: This is a test
The new string is: Ths s tst
PL/SQL procedure successfully completed.
You can use REGEXP_REPLACE() (though you certainly don't need commas in the character class - plus you don't need to replace with anything):
SELECT REGEXP_REPLACE('A penny for your thoughts','[aeiouAEIOU]')
FROM dual;
You can also use the following which might well be more efficient that using regular expressions (and which will work in Oracle 9i or lower, as well):
SELECT TRANSLATE('A penny for your thoughts', 'AEIOUaeiou', ' ')
FROM dual
Yes, this function call should do the trick:
SELECT REGEXP_REPLACE('A penny for your thoughts','[a,e,i,o,u,A,E,I,O,U]','')
FROM dual;
Related
I know that I can escape strings in a statement like this:
select 'That''s a really funny ''joke''' from dual; --returns: That's a really funny 'joke'
Or like this:
select q'[That's a really funny 'joke']' from dual; --returns: That's a really funny 'joke'
Both are working fine.
Let's say I need to escape a string exactly in that select statement and I also need to use a function.
select q'[myfunction(somestringvariable)]' from dual;
Of course this only returns "myfunction(somestringvariable)"
As said, I need to escape the results of the function (can't be done inside the function, escape needs to happen in this select statement).
Can I use the function somehow inside a string escaped with "q"?
Thanks!
To double single quotes in the function result:
REPLACE(myfunction(somestringvariable), '''', '''''')
Oracle does not support template literals.
Just use:
SELECT myfunction(somestringvariable) FROM DUAL;
or, if the function does not return a string:
SELECT TO_CHAR(myfunction(somestringvariable)) FROM DUAL;
If you want to concatenate a quoted string literal and a function result then use string concatenation.
SELECT q'[That's a really funny 'joke']'
|| myfunction(somestringvariable)
FROM DUAL;
Hi I have a stored procedure which accepts parameter "Q_RES" from java. Its value is either "Y" or "N" . In my stored procedure I have a condition
If Q_RES = 'Y' THEN
sp_stat = 'TABLENAME.RES IN (' || Q_RES || ')';
END IF
nut I get error has ORA-00904: "Y" invalid Identifier
How can I fix this?
In PL/SQL assignment is Pascal style :=', not=`. Aside from that, I don't see any problem with the string concatenation shown here.
I suspect that sp_stat is being used later, in composing dynamic SQL. I would take a close look at the SQL being generated. It's probably goign to look like this:
... TABLENAME.RES IN (Y) ...
And if that is interpreted as SQL text, Oracle is going to see that bareword Y as an identifier, such as a column name, and attempt to resolve that. (If a table referenced in the query has a column named Y, the query wouldn't throw an error about an invalid identifier.
Just guessing here, but I suspect that we want Y to be a string literal. A string literal is enclosed in single quotes, like this:
... TABLENAME.RES IN ('Y') ...
To get a single quote inside a string literal, we can use two single quotes, e.g.
'I''m happy this is working'
Since we already know Q_RES is equal to 'Y', why not just do this:
sp_stat := 'TABLENAME.RES IN (''Y'')';
^^ ^^
or, if we want to reference Q_RES, enclose it in single quotes, like this:
sp_stat := 'TABLENAME.RES IN (''' || Q_RES || ''')';
^^ ^^
Input data:
abcdef_fhj_viji.dvc
Expected output:
fhj_viji.dvc
The part to be trimmed is not constant.
Use the REPLACE method
Select REPLACE('abcdef_fhj_viji.dvc','abcde','')
If you want this query for your table :
Select REPLACE(column,'abcde','') from myTable
For update :
UPDATE TABLE
SET column = REPLACE(column,'abcde','')
select substr('abcdef_fhj_viji.dvc',instr('abcdef_fhj_viji.dvc','_')+1) from dual
So, Its all depends on INSTR function, define from which position and which occurrence, you will get the index and pass that index to SUBSTR to get your string.
Since you didn't give a lot of information I'm gonna assume some.
Let's assume you want a prefix of some string to be deleted. A good way to do that is by using Regular Expressions. There's a function called regexp_replace, that can find a substring of a string, depending on a pattern, and replace it with a different string. In PL/SQL you could write yourself a function using regexp_replace, like this:
function deletePrefix(stringName in varchar2) return varchar2 is
begin
return regexp_replace(stringName, '^[a-zA-Z]+_', '');
end;
or just use this in plain sql like:
regexp_replace(stringName, '^[a-zA-Z]+_', '');
stringName being the string you want to process, and the ^[a-zA-Z]+_ part depending on what characters the prefix includes. Here I only included upper- and lowercase letters.
I have a table with a structure like this...
the_geom data
geom1 data1+3000||data2+1000||data3+222
geom2 data1+500||data2+900||data3+22232
I want to create a function that returns the records by user request.
Example: for data2, retrieve geom1,1000 and geom2, 900
Till now I created this function (see below) which works quite good but I am facing a parameter substitution problem... (you can see I am not able to substitute 'data2' for $1 in... BUT yes I can use $1 later
regexp_matches(t::text, E'(data2[\+])([0-9]+)'::text)::text)[2]::integer
MY FUNCTION
create or replace function get_counts(taxa varchar(100))
returns setof record
as $$
SELECT t2.counter,t2.the_geom
FROM (
SELECT (regexp_matches(t.data::text, E'(data2[\+])([0-9]+)'::text)::text)[2]::integer as counter,the_geom
from (select the_geom,data from simple_inpn2 where data ~ $1::text) as t
) t2
$$
language sql;
SELECT get_counts('data2') will work **but we should be able to make this substitution**:
regexp_matches(t::text, E'($1... instead of E'(data2....
I think its more a syntaxis issue, as the function execution gives no error, just interprets $1 as a string and gives no result.
thanks in advance,
A E'$1' is a string literal (using the escape string syntax) containing a dollar sign followed by a one. An unquoted $1 is the first parameter to your function. So this:
regexp_matches(t, E'($1[\+])([0-9]+)'))[2]::integer
as you've found, won't interpolate the $1 with the function's first parameter.
The regex is just a string, a string with an internal structure but still just a string. If you know that $1 will be a normal word then you could say:
regexp_matches(t, E'(' || $1 || E'[\+])([0-9]+)'))[2]::integer
to paste your strings together into a suitable regex. However, it is better to be a little paranoid, sooner or later someone is going to call your function with a string like 'ha ha (' so you should be prepared for it. The easiest way that I can think of to add an arbitrary string to a regex is to escape all the non-word characters:
-- Don't forget to escape the escaped escapes! Hence all the backslashes.
str := regexp_replace($1, E'(\\W)', E'\\\\\\1', 'g');
and then paste str into the regex as above:
regexp_matches(t, E'(' || str || E'[\+])([0-9]+)'))[2]::integer
or better, build the regex outside the regexp_matches to cut down on the nested parentheses:
re := E'(' || str || E'[\+])([0-9]+)';
-- ...
select regexp_matches(t, re)[2]::integer ...
PostgreSQL doesn't have Perl's \Q...\E and the (?q) metasyntax applies until the end of the regex so I can't think of any better way to paste an arbitrary string into the middle of a regex as a non-regex literal value than to escape everything and let PostgreSQL sort it out.
Using this technique, we can do things like:
=> do $$
declare
m text[];
s text;
r text;
begin
s = E'''{ha)?';
r = regexp_replace(s, E'(\\W)', E'\\\\\\1', 'g');
r = '(ha' || r || ')';
raise notice '%', r;
select regexp_matches(E'ha''{ha)?', r) into m;
raise notice '%', m[1];
end$$;
and get the expected
NOTICE: ha'{ha)?
output. But if you leave out the regexp_replace escaping step, you'll just get an
invalid regular expression: parentheses () not balanced
error.
As an aside, I don't think you need all that casting so I removed it. The regexes and escaping are noisy enough, there's no need to throw a bunch of colons into the mix. Also, I don't know what your standard_conforming_strings is set to or which version of PostgreSQL you're using so I've gone with E'' strings everywhere. You'll also want to switch your procedure to PL/pgSQL (language plpgsql) to make the escaping easier.
How can I parse the value of "request" in the following string in Oracle?
<!-- accountId="123" activity="add" request="add user" -->
The size and the position of the request is random.
You can use regular expressions to find this:
regexp_replace(str, '.*request="([^"]*)".*', '\1')
Use INSTR(givenstring, stringchartosearch,start_position) to find the position of 'request="' and to find the position of the closing '"'.
Then use substr(string, starting_position, length).
You'd use a combination of instr and substr
THIS EXAMPLE IS FOR EXAMPLE PURPOSES ONLY. DO NOT USE IT IN PRODUCTION CODE AS IT IS NOT VERY CLEAN.
substr(my_str,
-- find request=" then get index of next char.
instr(my_str, 'request="') + 9,
-- This is the second " after request. It does not allow for escapes
instr(substr(my_str,instr(my_str, 'request="')), 2))
Below is my tested variations from cwallenpoole and Craig. For the regexp - note that if "request=" does not exist, the result will be the entire string. user349433 was partly there too, a space before "request=" in the search works just as well:
SET serveroutput ON
DECLARE
l_string VARCHAR2(100) := '<!-- accountId="123" activity="add" request="add user" -->';
l_result_from_substr VARCHAR2(50);
l_result_from_regexp VARCHAR2(50);
BEGIN
SELECT SUBSTR(l_string, instr(l_string, 'request="') + 9, instr(SUBSTR(l_string,instr(l_string, 'request="')), '"', 2)-1),
regexp_replace(l_string, '.* request="([^"]*)".*', '\1')
INTO l_result_from_substr,
l_result_from_regexp
FROM dual;
dbms_output.put_line('Result from substr: '||l_result_from_substr);
dbms_output.put_line('Result from regexp: '||l_result_from_regexp);
END;
/
Please note the equal sign "=" does not necessarily have to come immediately after the request variable in the assignment. As such, it is not entirely correct to search for "request=". You should create a basic finite state machine using INSTR to first find "request", then find "=", ...