I want to write a function that will give me the next version number for a table. The table stores the existing version on each record. For example,
I have the cat table
cats
seqid 1
name Mr Smith
version number 1.2b.3.4
How can I write a program that will be able to increment these values based on various conditions?
This is my first attempt
if v_username is not null
then v_new_nbr = substr(v_cur_nbr, 1,7)||to_number(substr(v_cur_nbr, 8,1))+1
should be 1.2b.3.5
substr(v_cur_nbr, 1,7)||to_number(substr(v_cur_nbr, 8,1))+1
This hurls ORA-01722: invalid number. The reason is a subtle one. It seems Oracle applies the concatenation operator before the additions, so effectively you're adding one to the string '1.2b.3.4'.
One solution is using a TO_CHAR function to bracket the addition with the second substring before concatenating the result with the first substring:
substr(v_cur_nbr, 1,7) || to_char(to_number(substr(v_cur_nbr, 8,1))+1)
Working demo on db<>fiddle.
Incidentally, a key like this is a bad piece of data modelling. Smart keys are dumb. They always lead to horrible SQL (as you're finding) and risk data corruption. A proper model would have separate columns for each element of the version number. We can use virtual columns to concatenate the version number for display circumstances.
create table cats(
seqid number
,name varchar2(32)
,major_ver_no1 number
,major_ver_no2 number
,variant varchar2(1)
,minor_ver_no1 number
,minor_ver_no2 number
,v_cur_nbr varchar2(16) generated always as (to_char(major_ver_no1,'FM9') ||'.'||
to_char(major_ver_no2,'FM9') ||'.'||
variant ||'.'||
to_char(minor_ver_no1,'FM9') ||'.'||
to_char(minor_ver_no2,'FM9') ) );
So the set-up is a bit of a nause but incrementing the version numbers is a piece of cake.
update cats
set major_ver_no1 = major_ver_no1 +1
, major_ver_no2 = 0
, variant = 'a';
There's a db<>fiddle for that too.
Try searching mask for TO_NUMBER to be able to get the decimal number, this small example might help:
CREATE TABLE tmp_table (version varchar2(100));
INSERT INTO tmp_table(version) VALUES ('1.2b.3.4');
DECLARE
mainVersion NUMBER;
subVersion NUMBER;
currentVersion VARCHAR2(100);
BEGIN
SELECT version INTO currentVersion FROM tmp_table;
mainVersion := TO_NUMBER(SUBSTR(currentVersion,1,3),'9.9') + 0.1;
subVersion := TO_NUMBER(SUBSTR(currentVersion,6,3),'9.9') + 1.1;
UPDATE tmp_table SET version = (mainVersion||'b.'||subVersion);
END;
Related
We want to convert our database (oracle 11g) from this character set: ISO-8859-8
to this character set: AL32UTF8.
The new mode need to support European characters and more.
Those languages can appear in a lot of tables.
I want to get some estimate about the new size of tables\whole database
according to the the current data.
Is there a good way to do that?
I don't think it will change much. I presume your VARCHAR2 columns are currently defined like VARCHAR2(30), which by default means VARCHAR2(30 BYTE). And that will remain unchanged after the conversion. If you defined them as VARCHAR2(30 CHAR), I'm not sure what would happen. When you define a column with character symantics, I think Oracle reserves as much space as it might need, which is 4 bytes per character for AL32UTF8.
I don't understand why you are so concerned about the size. Perhaps the DB will be a few(!) percent larger, most likely you will not notice any difference.
Anyway, this PL/SQL should give some idea on the size:
declare
iso_size number;
utf8_size number;
iso_size_sum number := 0;
utf8_size_sum number := 0;
begin
for aCol in (select table_name, column_name from user_tab_cols where data_type = 'VARCHAR') loop
iso_size.extend;
utf8_size.extend;
execute immediate
'select sum(LENGTH('||aCol.column_name||')),
sum(LENGTHB(convert('||aCol.column_name||', ''AL32UTF8'')))
from '||aCol.table_name INTO iso_size, utf8_size;
iso_size_sum := iso_size_sum + iso_size;
utf8_size_sum := utf8_size_sum + utf8_size ;
end loop;
dbms_output.put_line('Current size: '||to_char(iso_size_sum/1024/1024))||' MiByte');
dbms_output.put_line('Estimated UTF-8 size: '||to_char(utf8_size_sum/1024/1024))||' MiByte');
end;
The two numbers should give you an indication(!) how much the database would grow. Note, the data in Oracle are organized in Blocks (typically 8 kiBytes) not bytes.
Due to performance reasons you should run the query only on one representative table not the entire schema.
Select count(*) from table where loc between 300 to 400.
loc is a varchar column.
it is not selecting all the data
checking the count, gives ORA :01722 error
exporting the results with error.
Edit from comment:
loc contains values less than 300, more than 400, and alphanumeric like 'GT' , '3KT1'
loc is a varchar column.
[From comment] The Loc column has char type value also like GJ, 3KT1
LOC contains values which are not convertible to numbers. This matters because your WHERE clause predicates are defined as numbers, so Oracle applies an implicit to_number(loc) to the query. This is why using proper data types is best practice: it doesn't help you now but please learn the lesson, and use NUMBER columns for numeric data.
In the meantime you have several options to deal with your shonky data model.
If you're lucky enough to be using Oracle 12c R2 you can use the new VALIDATE_CONVERSION() function to exclude values of loc which can't be cast to numbers. Find out more
If you're using an earlier version of Oracle you can build your own function:
create or replace function is_number
(p_str in varchar2) return number
is
n number;
rv number;
begin
begin
n := to_number(p_str);
rv := 1;
exception
when invalid_number then
rv := 0;
end;
return rv;
end;
The weakest option would be casting the predicates to strings. where loc between '300' to '400' would include '3000', '4' and various other values you probably don't want.
Here is a LiveSQL demo (free Oracle Technet account required, alas).
Your current query is trying to compare a varchar to a number. So it tries to convert the varchar to a number on the fly. This is called implicit conversion.
You should make it compare a varchar to a varchar.
Use single quotes so that you are comparing to varchars, not numbers
Select count(*) from table where loc between '300' to '400'
Then go and read about implicit conversion
Based on the update to your question, this column is a legitimate varchar and should not be converted to a numeric data type.
However you do need to work out whether you are incorrectly storing different types of data in the same column
I have function which returns column names and i am trying to use the column name as part of my select statement, but my results are coming as column name instead of values
FUNCTION returning column name:
get_col_name(input1, input2)
Can И use this query to the results of the column from table -
SELECT GET_COL_NAME(input1,input2) FROM TABLE;
There are a few ways to run dynamic SQL directly inside a SQL statement. These techniques should be avoided since they are usually complicated, slow, and buggy. Before you do this try to find another way to solve the problem.
The below solution uses DBMS_XMLGEN.GETXML to produce XML from a dynamically created SQL statement, and then uses XML table processing to extract the value.
This is the simplest way to run dynamic SQL in SQL, and it only requires built-in packages. The main limitation is that the number and type of columns is still fixed. If you need a function that returns an unknown number of columns you'll need something more powerful, like the open source program Method4. But that level of dynamic code gets even more difficult and should only be used after careful consideration.
Sample schema
--drop table table1;
create table table1(a number, b number);
insert into table1 values(1, 2);
commit;
Function that returns column name
create or replace function get_col_name(input1 number, input2 number) return varchar2 is
begin
if input1 = 0 then
return 'a';
else
return 'b';
end if;
end;
/
Sample query and result
select dynamic_column
from
(
select xmltype(dbms_xmlgen.getxml('
select '||get_col_name(0,0)||' dynamic_column from table1'
)) xml_results
from dual
)
cross join
xmltable
(
'/ROWSET/ROW'
passing xml_results
columns dynamic_column varchar2(4000) path 'DYNAMIC_COLUMN'
);
DYNAMIC_COLUMN
--------------
1
If you change the inputs to the function the new value is 2 from column B. Use this SQL Fiddle to test the code.
I am making a web application which uses a database in which I have a field I_ID which i want to automatically increment like I0 then I1 then I2 and so on with each record insertion in the database.
To achieve it I made a trigger for this table.But its not working fine.What can be the reason.Please help
My Trigger T1:
CREATE OR REPLACE TRIGGER "T1"
before
insert on "TBINDIVIDUAL"
for each row
declare
x varchar2(10);
mx varchar2(13);
mx2 varchar2(13);
y number(3);
begin
x:=:new.I_ID;
mx:=substr(x,1,1);
select max(I_ID) into mx2 from tbindividual where I_ID like mx||'%';
y:=to_number(substr(mx2,2));
:new.I_ID:=mx||to_char(y+1);
end t1;
/
EDITED :
As i do by answer
CREATE OR REPLACE TRIGGER "TBINDIVIDUAL_T1"
BEFORE
insert on "TBINDIVIDUAL"
for each row
begin
:new.I_ID = SEQ1.nextval;
end;
/
But it give two errors
Encountered the symbol "=" when expecting one of the following: := . ( # % ; indicator
Encountered the symbol "END"
Please help
So Oracle is not SQL Server...
if you want to get unique ID's, you need to populate them from a sequence.
for creating a sequence use:
create sequence myseq;
and in your code use (depends on the version):
:new.I_ID := myseq.nextval;
or
select myseq.nextval into :new.I_ID from dual;
the problem your code doesn't work is what :new and :old means...
I would recommend you reading about their meaning...
Hope I've been helpful...
Because of the discussion in the comments - here is a full example:
for this table:
CREATE TABLE test (A number);
to add a unique, sequential ID you need to first create a sequence:
CREATE SEQUENCE myseq;
and a trigger:
CREATE OR REPLACE TRIGGER "T1"
before
insert on "test"
for each row
begin
:new.I_ID := myseq.nextval;
end t1;
/
by the way - I would recommend to check before substituting :new.I_ID, if it is null or not, cause sometimes in upgrades people add a unique ID from an external resource.. (such as them getting a unique number from the sequence themselves...)
you can read more about sequences here:
http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_6015.htm#SQLRF01314
sorry for the way the code is displayed.. need to learn how to write code here...
One more thing - In Oracle - you cannot create such a PL/SQL to increase existing counter without locks.
Concurrent queries might run the first query in the PL/SQL simultaneously, which means multiple sessions will get the same I_ID.
Also notice that in your code you queried the max on varchar, which is not the same as max on number...
Adding concatenated text is unrelated to the unique ID. In your case it will look like:
:new.I_ID = substr(:new.I_ID,1,1)||to_char(myseq.nextval);
assuming x is being inputted with the char you want..
Example if an ID is 1213 i want show **13.
If it's a number
select '**' || substr(to_char(id),3)
from my_table
Or, if it's already a character
select '**' || substr(id,3)
from my_table
This concatenates ** onto the beginning of the string, using the Oracle concatenation operator || and removes the first two characters of the id using substr.
Here's a SQL Fiddle to demonstrate.
If you don't want to sacrifice performance too much, to mask first two characters you can use-
SQL> select regexp_replace('1213','(.)2','**') from dual; --if VARCHAR
MASKED
------------
**13
SQL> select regexp_replace(1213,'(.)2','**') from dual; --if NUMBER
MASKED
------------
**13
REGEXP_REPLACE will work alike on NUMBER and VARCHAR so you save some conversion time there.
Consecutively, you can create a Function Based Index on the regexp function operation to optimize the query like (considering you would always want to mask only first two characters of ID) -
CREATE INDEX
mask_id
ON
table_name
(regexp_replace(id,'(.)2','**'));