Is it possible to shortner your SQL function like in C# or Java with lambda.
set serveroutput on;
CREATE OR REPLACE
FUNCTION Two(n IN INT) RETURN FLOAT AS
s FLOAT;
Begin
s:=0;
FOR i in 0..n LOOP
s:=s+1 / POWER(2,i);
END LOOP;
return s;
END Two;
/
Begin
DBMS_OUTPUT.PUT_LINE(Two(2));
END;
/
This is how my functions looks like, I feel it's kind of long for the job it does.
How could I shortner it ?
Is it possible to shortner your SQL function like in C# or Java with lambda.
No, there is no lambda syntax in PL/SQL.
How could I shortner it ?
You can just use 2 - 2-n:
CREATE FUNCTION Two(n IN INT) RETURN FLOAT
AS
BEGIN
RETURN 2 - POWER(2,-n);
END Two;
/
db<>fiddle here
Related
My database (PostgreSQL 11) has a function that must be called to execute an action. The return is not important, as long as there's no error. This function has arguments that must be passed as parameters.
I cannot directly use TFDConnection.ExecSQL because I use parameters of type array that is not supported by the method (to my knowledge). So, I use TFDQuery.ExecSQL like this:
msql1: = 'DO $$ BEGIN PERFORM DoIt (:id,:items); END $$; ';
{... create FDQuery (fq), set connection, set SQL.Text to msql1}
fq.Params.ParamByName ('id'). AsInteger: = 1;
{$ REGION 'items'}
fq.ParamByName ('items'). DataType: = ftArray;
fq.ParamByName ('items'). ArrayType: = atTable; // Must be atTable, not atArray
if length (items)> 0 then
begin
fq.ParamByName ('items'). ArraySize: = length (items);
for it: = 0 to length (items) -1 do
fq.ParamByName ('items'). AsIntegers [it]: = items [it];
end;
fq.ExecSQL;
{$ ENDREGION}
When executing the above code, the error above message raises
"Parameter 'id' not found".
After some research that suggested using fq.Params.ParamByName I was also unsuccessful.
However, if you change the way the function is called to
select DoIt (:id,:items); and obviously replacing the execution with fq.Open works perfectly.
Is it possible to execute a PL / pgSQL block that contains parameters in the function called by this block using TFDConnection / TFDQuery?
PS: I'm using Delphi Rio 10.3.3
When you assign a value to TFDQuery.SQL, FireDAC does some pre-processing of the SQL based on various options. ResourceOptions.CreateParams option controls whether parameters should be processed. This is enabled by default.
The preprocessor recognizes string literals in your SQL and doesn't try to look for the parameters in them. You used dollar quoted string constant and that's why FireDAC doesn't recognize parameters in it. Even if you add parameter manually I think that FireDAC would not bind the value.
With that said, the proper way to execute stored procedures/function is to use TFDStoredProc. You just assign StoredProcName and call its Prepare method which will retrieve procedure's metadata (parameters) from database so you don't need to set ArrayType or DataType of the parameter.
In your code you set the DataType to ftArray which is wrong, because in case of array parameter it should be set to array's element type. Anyway, by setting fq.ParamByName ('items').AsIntegers you effectively set parameter's DataType to ftInteger. All you need to do is to set ArraySize
Here's what you should do instead:
procedure DoIt(Connection: TFDConnection; ID: Integer; const Items: TArray<Integer>);
var
StoredProc: TFDStoredProc;
ParamItems: TFDParam;
Index: Integer;
begin
StoredProc := TFDStoredProc.Create(nil);
try
StoredProc.Connection := Connection;
StoredProc.StoredProcName := 'DoIt';
StoredProc.Prepare;
StoredProc.Params.ParamByName('id').AsInteger := ID;
if Length(Items) > 0 then
begin
ParamItems := StoredProc.Params.ParamByName('items');
ParamItems.ArraySize := Length(Items);
for Index := Low(Items) to High(Items) do
ParamItems.AsIntegers[Index] := Items[Index];
end;
StoredProc.ExecProc;
finally
StoredProc.Free;
end;
end;
Alternatively you can use ExecFunc to get the result of stored function.
Example:
Figure_t base class (super class)
sphere_t under figure_t
pyramid_t under figure_t
both has volume.
How to do objects comparison using map or order function?
What I am doing is using the map member function in the super class for comparing using the volume. I have tried with/without override of the map function in the subclass but still no luck. I can compare if I create the same object twice but not if I create different ones.
In example below I paste just the sphere since it is almost the same for both sphere and pyramid.
This is my super class:
CREATE OR REPLACE TYPE figure_t AS OBJECT (
v_volume NUMBER,
v_area NUMBER,
MAP MEMBER FUNCTION compare RETURN NUMBER, PRAGMA restrict_references ( compare, wnds, trust )
);
/
CREATE OR REPLACE TYPE BODY figure_t AS
MAP MEMBER FUNCTION compare RETURN NUMBER IS
BEGIN
RETURN v_volume;
END;
END;
/
ALTER TYPE figure_t NOT FINAL
CASCADE;
/
Then, this is my subtype:
CREATE OR REPLACE TYPE sphere_t UNDER figure_t (
v_radio NUMBER,
CONSTRUCTOR FUNCTION sphere_t (
radio NUMBER
) RETURN SELF AS RESULT,
MEMBER FUNCTION get_volume RETURN NUMBER,
MEMBER FUNCTION get_area RETURN NUMBER,
OVERRIDING MAP MEMBER FUNCTION compare RETURN NUMBER
);
/
CREATE OR REPLACE TYPE BODY sphere_t AS
CONSTRUCTOR FUNCTION sphere_t (
radio NUMBER
) RETURN SELF AS RESULT IS
BEGIN
self.v_radio := radio;
self.v_volume := ( 4 / 3 ) * 3.141592654 * power(radio, 3);
self.v_area := 4 * 3.141592654 * power(radio, 2);
return;
END;
MEMBER FUNCTION get_volume RETURN NUMBER IS
BEGIN
RETURN v_volume;
END;
MEMBER FUNCTION get_area RETURN NUMBER IS
BEGIN
RETURN v_area;
END;
OVERRIDING
MAP MEMBER FUNCTION compare RETURN NUMBER IS
BEGIN
RETURN self.v_volume;
END;
END;
/
For doing the comparison it looks like:
DECLARE
sphere_v sphere_t;
pyramid_v pyramid_t;
BEGIN
pyramid_v := pyramid_t(120, 90, 30);
sphere_v := sphere_t(10);
IF ( sphere_v != pyramid_v ) THEN
dbms_output.put_line('NOT EQUAL');
END IF;
END;
There should be a way for this comparison since figures have a super class in common.
There should be a way for this comparison since figures have a super
class in common
Am not very sure as what you wanted to achieve here. Also what is definition of pyramid_t which you are using in your comparison.
IF ( sphere_v != pyramid_v ) THEN
The above condition looks dicey to me as this will always be the case.
When you do sphere_v := sphere_t(10); means you try to get all the return of the sphere_t to sphere_v.
So it would be good if you could compare the volume and area of the Sphere and pyramid separately. See below demo how you could take these value:
DECLARE
sphere_v sphere_t;
-- pyramid_v pyramid_t;
BEGIN
sphere_v := sphere_t(10);
dbms_output.put_line('Input Radio -->'||sphere_v.v_radio);
dbms_output.put_line('Volume of Sphere-->'||sphere_v.v_volume);
dbms_output.put_line('Area Of Sphere -->'||sphere_v.v_area);
--Similarly you can take the values of `volume` and `area`
--of pyramid and get it compared with that of Sphere.
-- pyramid_v := pyramid_t(120, 90, 30);
-- dbms_output.put_line('Input Radio Pyramid -->'||pyramid_v.v_radio);
-- dbms_output.put_line('Volume of Pyramid -->'||pyramid_v.v_volume);
-- dbms_output.put_line('Area Of Pyramid -->'||pyramid_v.v_area);
-- If sphere_v.v_volume = pyramid_v.v_volume then
-- dbms_output.put_line('Equal');
-- Else
-- dbms_output.put_line('Not Equal');
END;
Assumption: pyramid_t also have the same Object Body definition having volume and area calculation.
There should be a way for this comparison since figures have a super class in common.
There is a way, it's just not obvious.
When the types are exactly the same e.g. two instances of the same subtype we can invoke the map function implicitly. So we can compare two spheres like this:
IF ( sphere_1 != sphere_2 ) THEN ...
However, to compare two different subtypes we need to invoke the parent map function, and to make this happen we must reference it explicitly:
IF ( sphere_v.compare() != pyramid_v.compare() ) THEN ...
Yes, this is clunky. But Oracle is an RDBMS not an ORDBMS (whatever they claimed back in the version 8.0 days).
I have SMDBGrid component with show filter bar option set to true, but filter just working in case-sensitive mode
1.Try with lower case
2.Try with upper case
I have tried to insert the code in SMDBgrid.pas like this
procedure TSMDBGrid.ApplyFilter;
var
TempCol: Integer;
begin
if (eoFilterAutoApply in ExOptions) then
begin
TempCol := LeftCol;
BeginUpdate;
try
if DataLink.Active then
begin
DataLink.DataSet.CheckBrowseMode;
DataLink.DataSet.Filtered := False;
DataLink.DataSet.OnFilterRecord := nil;
DataLink.DataSet.OnFilterRecord := OnFilterRecord;
DataLink.DataSet.FilterOptions := [foCaseInsensitive]; <-- this the inserted code
DataLink.DataSet.Filtered := not FilterIsEmpty();//True;
end;
finally
LeftCol := TempCol;
EndUpdate;
end;
end;
if Assigned(OnFilterChanged) then
OnFilterChanged(Self);
end;
But no luck, Is posible filter the record ignoring the case?
PS:
I use Delphi 2009
You may use the OnAccentStringConvert event to transform the value for filter in column before compare:
begin
Result := UpperCase(S)
end;
Looks like I cope with this problem too. Trying to find any solution for Delphi XE 10.3 community edition and wrote to author of SMDBGrid and he found workaround.
Please use SQL ADOQuery as follows.
SELECT UPPER(field) FROM your_table
then use event OnAccentStringConvert and uppercase S String as follows:
function TYourFormName.DBGrridNameAccentStringConvert(Sender: TObject; const S: string): string;
begin
Result := UpperCase(S)
end;
This works very ugly, but at least works. Or you may just create filter by yourself for every table.
I have written a function minimum2 which take two numbers as arguments and returns the minimum number. This function compiles without any error. when I call the function minimum(1,2); I get the errors PLS-00103. Here is the function and the function call:
CREATE OR REPLACE FUNCTION minimum2(v1 number, v2 number) RETURN number IS
BEGIN
IF v1 < v2 THEN
RETURN v1;
ELSE
RETURN v2;
END IF;
END;
--I call the function asl follow
minimum2(1,2);
What did I do wrong? I wrote this code in sql developer
You need to run a select
select minimum2(1,2)
from dual
You also need to end the function with a /:
For details on how and why to use the / see here
Are you aware that there is a built-in function for that?
select least(1,2)
from dual
--specifying 'in' and 'out' to parameters is important or it can work as it is, but best practice is to use:
CREATE OR REPLACE FUNCTION minimum2(v1 IN number, v2 IN number) RETURN number IS
BEGIN
IF v1 < v2 THEN
RETURN v1;
ELSE
RETURN v2;
END IF;
END;
--I call the function as follows through anonymous block and you can not call the function directly.
set serveroutput on;
begin
dbms_output.put_line('Output is ' || minimum2(1,2));
END;
/
I have to move around 50+ validation functions into Oracle. I'm looking for the approach that runs fastest, but also would like to get around a boolean issue if possible. The return object for them all needs to be the same so that the application can react off the result in a consistent fashion and alert the user or display whatever popups, messages we may need. I created a valObj for this, but not sure yet if that is the best approach. The return format can be changed because the front-end that reacts off of it is not developed yet. In the end it will contain many different validation functions, from integer, number, phone, email, IPv4, IPv6, etc... This is what I have so far...
/***
This is the validation object.
It stores 1 for valid, 0 for not valid and some helper text that can be relayed back to the user.
***/
create or replace type valObj as object (
result number(1),
resultText varchar(32000)
);
/***
Coming from ColdFusion this seems clean to me but the function
will end up being a couple thousand lines long.
***/
create or replace function isValid(v in varchar2, format in varchar2)
return valObj
is
test number;
begin
if format = 'number' then
begin
test := to_number(v);
return valObj(1,null);
exception when VALUE_ERROR then return valObj(0,'Invalid number. Valid formats are: 12345, 12345.67, -12345, etc...');
end;
elsif format = 'integer' then
null; --TO DO
elsif format = 'email' then
null; --TO DO
elsif format = 'IPv4' then
null; --TO DO
elsif format = 'IPv6' then
null; --TO DO
end if;
--dozens of others to follow....
end;
/
/* Example Usage in SQL */
select isValid('blah','number') from dual; -- returns: (0, Invalid number. Valid formats are: 12345, 12345.67, -12345, etc...)
select isValid('blah','number').result from dual; -- returns: 0
select isValid('blah','number').resulttext from dual; -- returns: Valid formats are: 12345, 12345.67, -12345, etc...
select isValid(1234567890.123,'number') from dual; -- returns: 1,{null}
select isValid(1234567890.123,'number').result from dual; -- returns: 1
select isValid(1234567890.123,'number').resulttext from dual; -- returns: {null}
/* Example Usage in PL/SQL */
declare
temp valObj;
begin
temp := isValid('blah','number');
if (temp.result = 0) then
dbms_output.put_line(temp.resulttext);
else
dbms_output.put_line('Valid');
end if;
end;
/
My questions are:
When using it in PL/SQL I would love to be able to do boolean checks instead like this: if (temp.result) then but I can't figure out a way, cause that won't work in SQL. Should I just add a 3rd boolean attribute to the valObj or is there another way I don't know of?
These validation functions could end up being called within large loops. Knowing that, is this the most efficient way to accomplish these validations?
I'd appreciate any help. Thanks!
UPDATE: I forgot about MEMBER FUNCTIONS. Thanks #Brian McGinity for reminding me. So I'd like to go with this method since it keeps the type and its functions encapsulated together. Would there be any speed difference between this method and a stand-alone function? Would this be compiled and stored the same as a stand-alone function?
create or replace type isValid as object (
result number(1),
resulttext varchar2(32000),
constructor function isValid(v varchar, format varchar) return self as result );
/
create or replace type body isValid as
constructor function isValid(v varchar, format varchar) return self as result as
test number;
begin
if format = 'number' then
begin
test := to_number(v);
self.result := 1;
self.resulttext := null;
return;
exception when VALUE_ERROR then
self.result := 0;
self.resulttext := 'Invalid number. Valid formats are: 12345, 12345.67, -12345, etc...';
return;
end;
elsif format = 'phone' then
null; --TO DO
end if;
--and many others...
end;
end;
/
/* Example Usage in SQL */
select isValid('a','number') from dual;
/* Example Usage in PL/SQL */
declare
begin
if (isValid('a','number').result = 1) then
null;
end if;
end;
/
TEST RESULTS:
/* Test isValid (the object member function), this took 7 seconds to run */
declare
begin
for i in 1 .. 2000000 loop
if (isValid('blah','number').result = 1) then
null;
end if;
end loop;
end;
/* Test isValid2 (the stand-alone function), this took 16 seconds to run */
declare
begin
for i in 1 .. 2000000 loop
if (isValid2('blah','number').result = 1) then
null;
end if;
end loop;
end;
Both isValid and isValid2 do the same exact code, they just run this line test := to_number(v); then do the exception if it fails and return the result. Does this appear to be a valid test? The Object member function method is actually faster than a stand-alone function???
The stand-alone function can be much faster if you set it to DETERMINISTIC and if the data is highly repetitive. On my machine this setting decreased run time from 9 seconds to 0.1 seconds. For reasons I don't understand that setting does not improve performance of the object function.
create or replace function isValid2(v in varchar2, format in varchar2)
return valObj
deterministic --<< Hit the turbo button!
is
test number;
begin
if format = 'number' then
begin
test := to_number(v);
return valObj(1,null);
exception when VALUE_ERROR then return valObj(0,'Invalid number. Valid formats are: 12345, 12345.67, -12345, etc...');
end;
end if;
end;
/
May also want to consider utilizing pls_integer over number. Don't know if it will buy you much, but documents suggest some gain will be had.
http://docs.oracle.com/cd/B10500_01/appdev.920/a96624/03_types.htm states,
"You use the PLS_INTEGER datatype to store signed integers. Its magnitude range is -2*31 .. 2*31. PLS_INTEGER values require less storage than NUMBER values. Also, PLS_INTEGER operations use machine arithmetic, so they are faster than NUMBER and BINARY_INTEGER operations, which use library arithmetic. For efficiency, use PLS_INTEGER for all calculations that fall within its magnitude range."