I have one challenge:
I have the following code in SQL Server and I want to move it to PostgreSQL DBMS.
I adapted it to PostgreSQL just like the following:
CREATE function public.SEMANA_ISO (fecha date) returns integer as $$
DECLARE
semana_ISO int= date_part ('week',fecha)+1
-date_part('week',CAST(date_part('year',fecha) as CHAR(4)) + '0104');
BEGIN
IF (semana_ISO=0)
THEN
semana_ISO=public.SEMANA_ISO(CAST(date_part('year',fecha)-1
AS CHAR(4)) + '12' + CAST(24 + date_part('day',fecha) AS CHAR(2)))+1;
ELSIF ((date_part('month',fecha)=12) AND ((date_part('day',fecha)-date_part('day',fecha))>=28))
THEN
semana_ISO=1;
END IF;
RETURN semana_ISO;
END;
$$ LANGUAGE plpgsql;
As you may see, I tried to make it look the most similar as in SQL Server is.
However when I try to run this function and test it:
Select public.SEMANA_ISO('28/12/2014');
The DMBS shows many errors:
ERROR: operator does not exist: character + unknown
LINE 2: ...rt('week',CAST(date_part('year',fecha) as CHAR(4)) + '0104')
HINT: No operator matches the name and type of the arguments. You may need to add explicit type casts.
QUERY: SELECT date_part ('week', date) +1
-date_part ('week', CAST (date_part ('year', date) as CHAR (4)) + '0104')
CONTEXT: PL / pgSQL function semana_iso (date) at line 5 during initialization of local variables in the statement block
What I try to do is the following.
From the following input date format: dd/mm/yyyy I want to use the function above to show it as the next output format:mm-dd-yyyy
I have thought in doing a simpler function that could receive the date in the format given (dd/mm/yyyy) and using the set datestyle = mdy statement change it in the body of the function and finally print it or return it.
What do you suggest folks?
Your help & time is always appreciated!
A guess you may need a Function like below
CREATE function a_date_conv (fecha date) returns text as $$
select to_char(fecha, 'mm-dd-yyyy');
$$ LANGUAGE sql;
select a_date_conv('08/10/2014')
Result
-------
10-08-2014
Related
I am getting this error message
RETURN statements in scalar valued functions must include an argument
when run this query:
create function gender(#gender nvarchar(40))
returns nvarchar(40)
as
begin
(select name,cast(DOB as date) as DOB from datenames where gender = #gender)
return
end
The write way to create a function in mysql for your example is as follows:
DELIMITER \\
create function gender(Igender nvarchar(40))
returns nvarchar(40)
begin
DECLARE customerLevel NVARCHAR(40);
IF EXISTS (select name,cast(DOB as date) as DOB from datenames where gender = Igender) THEN
SET customerLevel = 'SOMETHING1';
ELSE
SET customerLevel = 'SOMETHING2';
END IF;
RETURN (customerLevel);
end
No need to as
No need to # before input
You need to return something.
Don't forget to use DELIMITER.
If you use phpmyadmin and has problem with nvarchar read this post: Unrecognize data type nvarchar in database or simply change it to to varchar.
If I have a TABLE named MyTable which has columns say C1(type date) and C2 (type character) I want to create a stored function that takes an input and the input should always belong to C1, and the output of the stored function should be the corresponding element in C2. I have tried to do it using the 'select' statement followed by 'where' clause inside the stored function but was not able to achieve it. Is there any other way to accomplish this task.
DELIMITER $$
CREATE FUNCTION `MyFunction`
(`Date` datetime)
RETURNS char(10)
BEGIN
DECLARE MyVariable char(10)
SELECT MyVariable = `C2`
FROM MyTable
WHERE `Date` = `C1`; RETURN MyVariable;
END$$
DELIMITER ;
But this keeps giving me ERROR CODE: 1064
At first glance, I see a syntax error:
...
BEGIN
DECLARE MyVariable char(10) <-- needs a semicolon here
SELECT MyVariable = `C2`
...
Every statement within the body of your routine must end with a semicolon. See examples of DECLARE in this manual page: https://dev.mysql.com/doc/refman/8.0/en/local-variable-scope.html
It should be like this:
...
BEGIN
DECLARE MyVariable char(10);
SELECT MyVariable = `C2`
...
Re your comment:
Error 1415 means "cannot return a result set". Your stored function is doing a SELECT without putting the result into your declared local variable using an INTO keyword.
You appear to be trying to set the value of MyVariable using = but that's just making a comparison. It doesn't assign anything to MyVariable.
Without using INTO to assign the variable, your SELECT statement is by default returning a result set. This is allowed in a stored procedure, but not in a stored function. A stored function must return a single scalar value, not a result set.
...
BEGIN
DECLARE MyVariable char(10);
SELECT `C2` INTO MyVariable
FROM MyTable
WHERE `Date` = `C1`;
RETURN MyVariable;
END
P.S.: I edited your question to replace the term "user-defined function" with "stored function". These are two different things in MySQL. You are writing a stored function.
In MySQL, they use the term user-defined function (UDF) for a function you implement in C/C++ code and compile into the MySQL server. It's less common for developers to write this type of extension.
We have a monitor on our databases to check for ids approaching max-int or max-bigint. We just moved from MySQL, and I'm struggling to get a similar check working on PostgreSQL. I'm hoping someone can help.
Here's the query in MySQL
SELECT table_name, auto_increment FROM information_schema.tables WHERE table_schema = DATABASE();
I'm trying to get the same results from PostgreSQL. We found a way to do this with a bunch of calls to the database, checking each table individually.
I'd like to make just 1 call to the database. Here's what I have so far:
CREATE OR REPLACE FUNCTION getAllSeqId() RETURNS SETOF record AS
$body$
DECLARE
sequence_name varchar(255);
BEGIN
FOR sequence_name in SELECT relname FROM pg_class WHERE (relkind = 'S')
LOOP
RETURN QUERY EXECUTE 'SELECT last_value FROM ' || sequence_name;
END LOOP;
RETURN;
END
$body$
LANGUAGE 'plpgsql';
SELECT last_value from getAllSeqId() as(last_value bigint);
However, I need to somehow add the sequence_name to each record so that I get output in records of [table_name, last_value] or [sequence_name, last_value].
So I'd like to call my function something like this:
SELECT sequence_name, last_value from getAllSeqId() as(sequence_name varchar(255), last_value bigint);
How can I do this?
EDIT: In ruby, this creates the output we're looking for. As you can see, we're doing 1 call to get all the indexes, then 1 call per index to get the last value. Gotta be a better way.
def perform
find_auto_inc_tables.each do |auto_inc_table|
check_limit(auto_inc_table, find_curr_auto_inc_id(auto_inc_table))
end
end
def find_curr_auto_inc_id(table_name)
ActiveRecord::Base.connection.execute("SELECT last_value FROM #{table_name}").first["last_value"].to_i
end
def find_auto_inc_tables
ActiveRecord::Base.connection.execute(
"SELECT c.relname " +
"FROM pg_class c " +
"WHERE c.relkind = 'S'").map { |i| i["relname"] }
end
Your function seems quite close already. You'd want to modify it a bit to:
include the sequences names as literals
returns a TABLE(...) with typed columns instead of SET OF RECORD because it's easier for the caller
Here's a revised version:
CREATE OR REPLACE FUNCTION getAllSeqId() RETURNS TABLE(seqname text,val bigint) AS
$body$
DECLARE
sequence_name varchar(255);
BEGIN
FOR sequence_name in SELECT relname FROM pg_class WHERE (relkind = 'S')
LOOP
RETURN QUERY EXECUTE 'SELECT ' || quote_literal(sequence_name) || '::text,last_value FROM ' || quote_ident(sequence_name);
END LOOP;
RETURN;
END
$body$
LANGUAGE 'plpgsql';
Note that currval() is not an option since it errors out when the sequence has not been set in the same session (by calling nextval(), not sure if there's any other way).
Would something as simple as this work?
SELECT currval(sequence_name) from information_schema.sequences;
If you have sequences that aren't keys, I guess you could use PG's sequence name generation pattern to try to restrict it.
SELECT currval(sequence_name) from information_schema.sequences
WHERE sequence_name LIKE '%_seq';
If that is still too many false positives, you can get table names from the information_schema (or the pg_* schemata that I don't know very well) and refine the LIKE parameter.
I am trying to have a conditional change in a parameter for update statement.
I am getting the following error when I try the following function
/home/y/bin/mysql -u root < testpri.sql > out
ERROR 1415 (0A000) at line 4: Not allowed to return a result set from a function
Contents of testpri.sql are as follows:
use `zestdb`;
DROP FUNCTION IF EXISTS UPDATEPASSWD;
DELIMITER //
CREATE FUNCTION UPDATEPASSWD(n INT) RETURNS varchar(255) DETERMINISTIC
BEGIN
DECLARE mypasswd varchar(255);
IF (n = 1) THEN
SET mypasswd = '12ccc1e5c3c9203af7752f937fca4ea6263f07a5';
SELECT 'n is 1' AS ' ';
ELSE
SET mypasswd = '1a7bc371cc108075cf8115918547c3019bf97e5d';
SELECT 'n is 0' AS ' ';
END IF;>
SELECT CONCAT('mypasswd is ', mypasswd) AS ' ';
RETURN mypasswd;
END //
DELIMITER ;
CALL UPDATEPASSWD(0);
What am I missing?
I think it's actually your debugging SELECT calls.
From the docs:
Statements that return a result set can be used within a stored procedure but not within a stored function. This prohibition includes SELECT statements that do not have an INTO var_list clause...
I arrived in search of answers to the same question, and found another way to work around the issue, so that I can use the SELECT statement that is the heart and soul of the MySQL function that elicited the warning.
Consider the following snippet.
SET intNMatches = ( SELECT COUNT(*) ...
SET coerces the SELECT statement to return its one and only column, a row count, into intNMatches, a local variable cast to BIGINT. Since it contains trade secrets, I can't show the rest of the query. Suffice it to say that the query installs without causing the MySQL engine to issue a warning.
I am using a pl/pgsql function that uses custom_variable_class, the function code is
CREATE OR REPLACE FUNCTION can_connect("pUserId" character varying)
RETURNS boolean AS
$BODY$DECLARE
user_id integer ;
BEGIN
SELECT users.user_serial INTO user_id
FROM public.users
WHERE users.user_id="pUserId"
;
set public.userId to user_id ;
set public.companyId to "pUserId" ;
RETURN true ;
EXCEPTION
WHEN OTHERS THEN
raise notice ' error %',sqlerrm ;
END ;
$BODY$
LANGUAGE plpgsql VOLATILE
Now using the function
select can_connect ('amr' );
t
it's ok, the return value is t as expected.
But when trying to retrive the session variable values
select current_setting('public.userId') ;
the result is
user_id
Which is variable name not the value
the same thing when using the function argument
select current_setting('public.pUserId') ;
the result is
pUserId
Thank you.
Use plpgsql EXECUTE to force the parser to interpolate the values of the variables:
EXECUTE 'set public.userId to ' || quote_literal(user_id);
EXECUTE 'set public.companyId to ' || quote_literal( "pUserId");
As a bonus it will also work with older versions of PostgreSQL.
It is allowed to SET only PostgreSQL's configuration parameters this way.
On PostgreSQL 9.1 I have the following output:
SET user_id TO bbb;
ERROR: unrecognized configuration parameter "user_id"
As PostgreSQL has no packages, the best way to keep state is to use temporary tables.