Before insert or update of any columns I want to update 1 system column with standard hash MD5 of all table columns, trigger is attached to. My intention is not to tailor this trigger with enumeration of all columns for each trigger and have a function that returns concatenated list of columns per table.
Table DDL:
create table TEST (
id int,
test varchar(100),
"_HASH" varchar(32)
);
Here is my trigger DDL that I would love to work :
CREATE TRIGGER TEST_SYS_HASH_BEFORE_INSERT_OR_UPDATE
BEFORE INSERT OR UPDATE
ON TEST
FOR EACH ROW
DECLARE
var_columns VARCHAR2(10000);
BEGIN
var_columns := FUNC_LISTAGG_EXT(‘TEST');
EXECUTE IMMEDIATE 'SELECT STANDARD_HASH(' || var_columns || ', ''MD5'') from dual'
INTO :new."_HASH";
END;
However this is simply taking headers and set same hash for every row. If I should do this manually , trigger would look like this, what works as I desire, but create it for several tens of tables would be overwhelming
CREATE OR REPLACE TRIGGER TEST_SYS_HASH_BEFORE_INSERT_OR_UPDATE
BEFORE INSERT OR UPDATE
ON TEST
FOR EACH ROW
DECLARE
var_columns VARCHAR(10000);
BEGIN
var_columns := FUNC_LISTAGG_EXT('TEST');
SELECT STANDARD_HASH( :new."ID" || :new."TEST" , 'MD5' )
INTO :new."_HASH";
FROM DUAL;
END;
So my question is whether solution is achievable
Note:
FUNC_LISTAGG_EXT function returns concatenated list of columns from system view
Related
I have a database of a video store, to ask the question that I have exposed, I thought about updating an age attribute that corresponds to the actors, but this doesn't make sense (as I show below in an example)
CREATE TABLE dobs ( dob date, age number(3));
insert into dobs values ((to_date('1999-10-04','yyyy-mm-dd')),NULL);
CREATE OR REPLACE FUNCTION get_age
(
fnacimiento date
)
return int
is edad int;
begin
select floor(months_between(sysdate,dob)/12) into edad
from dobs
where dob=fnacimiento;
return edad;
end get_age;
CREATE OR REPLACE TRIGGER agec before INSERT OR UPDATE ON dobs
FOR EACH ROW
BEGIN
:new.age := get_age(:new.dob);
END;
You don't need a function in order to update that column. Even no need to use a SELECT Statement. Just rearrange the trigger as :
CREATE OR REPLACE TRIGGER agec BEFORE INSERT OR UPDATE ON dobs
FOR EACH ROW
BEGIN
:new.age := floor(months_between(sysdate,:new.dob)/12);
END;
Trigger will be fired once at time of insert or update of record in the table so you will get the age of actor when insert/update is executed, not as of today.
So better solution is to create a view instead of trigger as follows:
Create or replace view dobs_vw
As
Select t.* floor(months_between(sysdate,t.dob)/12) as age_asof_today
From your_table t
I want to pass a table name and schema into a procedure, and have it generate insert, update and delete statements for the particular table. This is part of an automated testing solution (in a development environment) in which I need to test some change data capture. I want to make this dynamic as it is going to be need to be done for lots of different tables over a long period of time, and I need to call it via a REST request through ORDS, so don't want to have to make an endpoint for every table.
Update and delete are fairly easy, however I am struggling with the insert statement. Some of the tables being passed in have hundreds of columns with various constraints, fks etc. so I think it makes sense to just manipulate an existing record by changing only the primary key. I need to be able to modify the primary key to a new value known to me beforehand (e.g. '-1').
Ideally I would create a dynamic rowtype, and select into where rownum = 1, then loop round the primary keys found from all_constraints, and update the rowtype.pk with my new value, before inserting this into the table. Essentially the same as this but without knowing the table in advance.
e.g. rough idea
PROCEDURE manipulate_records(p_owner in varchar2, p_table in varchar2)
IS
cursor c_pk is
select column_name
from all_cons_columns
where owner = p_owner
and constraint_name in (select constraint_name
from all_constraints
where table_name = p_table
and constraint_type = 'P');
l_row tbl_passed_in%ROWTYPE --(I know this isn't possible but ideally)
BEGIN
-- dynamic sql or refcursor to collect a record
select * into tbl_passed_in from tablename where rownum = 1;
-- now loop through pks and reassign their values to my known value
for i in c_pk loop
...if matches then reassign;
...
end loop;
-- now insert the record into the table passed in
END manipulate_records;
I have searched around but haven't found any examples which fit this exact use case, where an unknown column needs to be modified and insert into a table.
Depending on how complex your procedure is, you might be able to store it as a template in a CLOB. Then pull it in, replace table and owner, then compile it.
DECLARE
prc_Template VARCHAR2(4000);
vc_Owner VARCHAR2(0008);
vc_Table VARCHAR2(0008);
BEGIN
vc_Table := 'DUAL';
vc_Owner := 'SYS';
-- Pull code into prc_Template from CLOB, but this demonstrates the concept
prc_Template := 'CREATE OR REPLACE PROCEDURE xyz AS r_Dual <Owner>.<Table>%ROWTYPE; BEGIN NULL; END;';
prc_Template := REPLACE(prc_Template,'<Owner>',vc_Owner);
prc_Template := REPLACE(prc_Template,'<Table>',vc_Table);
-- Create the procedure
EXECUTE IMMEDIATE prc_Template;
END;
Then you have the appropriate ROWTYPE available:
CREATE OR REPLACE PROCEDURE xyz AS r_Dual SYS.DUAL%ROWTYPE; BEGIN NULL; END;
But you can't create the procedure and run it in the same code block.
I am attempting to write a generic trigger that will provide all of the :NEW values for the row inserted. Ultimately I want to turn them into XML and insert the XML string into a binary field on another table.
There are a variable number of columns in each table - many times over 100 fields and over 100 tables in all, so individual mapping to XML per table is extremely time consuming.
Is there a way to reference the :NEW pseudorecord as a collection of column values - or perhaps a way to pass the whole :NEW record to a Stored Procedure that could pass it to a Java function (hosted on the database) that might make the individual values iterable?
I've found an example here:
https://docs.oracle.com/database/121/LNPLS/triggers.htm
Create history table and trigger:
CREATE TABLE tbl_history ( d DATE, old_obj t, new_obj t)
/
CREATE OR REPLACE TRIGGER Tbl_Trg
AFTER UPDATE ON tbl
FOR EACH ROW
BEGIN
INSERT INTO tbl_history (d, old_obj, new_obj)
VALUES (SYSDATE, :OLD.OBJECT_VALUE, :NEW.OBJECT_VALUE);
END Tbl_Trg;
/
This seems to imply there is some sort of way it is storing all of the values as a variable, but this appears to put them directly back into a database table. I want to get the 'text' values of the column values listed.
You can create a stored procedure to create your trigger
for table tbl like
create table tbl (id number, value varchar2(10));
and an history table like
create table tbl_history (d date,id number, value varchar2(10));
you can create your trigger like this
create or replace procedure CREATE_TRIGGER IS
trig_str VARCHAR2(32767);
col_str VARCHAR2(32767) := '(d';
values_str VARCHAR2(32767) := '(sysdate';
begin
trig_str := 'CREATE OR REPLACE TRIGGER Tbl_Trg AFTER UPDATE ON tbl FOR EACH ROW'||chr(10)||
'BEGIN'||chr(10)||chr(9)||'INSERT INTO tbl_history ';
for col in (
SELECT column_name FROM all_tab_columns where table_name = 'TBL'
) loop
col_str := col_str||','||col.column_name;
values_str := values_str||','||':OLD.'||col.column_name;
end loop;
col_str := substr(col_str,1,length(col_str)-1)||')';
values_str := substr(values_str,1,length(values_str)-1)||')';
trig_str := trig_str||col_str||' VALUES '||values_str||';'||chr(10)||'END;';
execute immediate trig_str;
END;
/
With an history table with old and new values it's a bit more complicated but same idea
I created a database in MySQL with ~10 tables, each starting with the column
SN INT NOT NULL AUTO_INCREMENT
SN doesn't mean anything, just the primary to differentiate between possibly repeating/similar names/titles, etc
I'm moving it to Oracle now, and found this post here on stackoverflow to make the trigger to auto increment the SN field. Basically,
CREATE SEQUENCE user_seq;
CREATE OR REPLACE TRIGGER user_inc
BEFORE INSERT ON users
FOR EACH ROW
BEGIN
SELECT user_seq.NEXTVAL
INTO :new.SN
FROM dual;
END;
/
Now, how can I rewrite that trigger once to apply to all the other tables? Because otherwise I have to rewrite it for many tables, just changing the trigger name and sequence name... I was picturing something like:
BEFORE INSERT ON users OR other_table OR another_one
I also found this post here, but the one answer there isn't helpful because I think it's reasonable for many tables to have the same SN field, or I'm misunderstanding the point.
Also, not Oracle 12c so no identity columns
Thanks in advance
I was going to just comment on the first post I mentioned but I can't comment without more reputation points :/
Creating a trigger referencing many tables in Oracle is not possible,
What you can do is to generate the triggers with a PL/SQL statement.
Below is an example on how could you achieve this
drop table tab_a;
drop table tab_b;
drop table tab_c;
drop sequence seq_tab_a_id;
drop sequence seq_tab_b_id;
drop sequence seq_tab_c_id;
--create test tables
create table tab_a (SN number, otherfield varchar2(30), date_field date);
create table tab_b (SN number, otherfield varchar2(30), date_field date);
create table tab_c (SN number, otherfield varchar2(30), date_field date);
-- this pl/sql block creates the sequences and the triggers
declare
my_seq_create_stmt varchar2(2000);
my_trigger_create_stmt varchar2(2000);
begin
for i in (select table_name
from user_tables
-- remember to change this where condition to filter
-- the tables that are relevant for you
where table_name in ('TAB_A', 'TAB_B', 'TAB_C') )loop <<TableLoop>>
my_seq_create_stmt := 'CREATE SEQUENCE '||'SEQ_'||i.table_name||'_ID '
||CHR(13)||' START WITH 1 INCREMENT BY 1 NOCYCLE ';
execute immediate my_seq_create_stmt;
my_trigger_create_stmt := 'CREATE OR REPLACE TRIGGER '||'TRG_'||i.Table_name||'_ID_BI '||' BEFORE INSERT ON '||i.table_name||' FOR EACH ROW '
||CHR(13)||'BEGIN '
||CHR(13)||' SELECT '||'SEQ_'||i.table_name||'_ID'||'.NEXTVAL '
||CHR(13)||' INTO :new.SN '
||CHR(13)||' FROM dual; '
||CHR(13)||'END; ';
execute immediate my_trigger_create_stmt;
end loop TableLoop;
end;
/
-- test the triggers and the sequences
insert into tab_a (otherfield, date_field) values ('test 1',sysdate);
insert into tab_a (otherfield, date_field) values ('test 2',sysdate);
commit;
Select * from tab_a;
The idea is, I want to clone the record as a CLOB when it is updated.
Why do it in such a way?
There are two different applications A1 and A2, A1 is depended on by A2.
Based on A1 values, calculations are made for values for A2.
The A2 process runs just once per day to calculate the values, but for A1 every field in the TABLE_NAME in question can be altered several times a day and doesn't have a history.
The aim is to create a history which is a CLOB field in a table "NEW_TABLE" of automatic form.
Sorry for my English, but if something is not understandable I can rewrite the question
My Code Here:
CREATE or REPLACE TRIGGER TRIGGER_NAME
AFTER UPDATE
ON TABLE_NAME
FOR EACH ROW
DECLARE
row_record NEW_TABLE%rowtype;
c_xml CLOB;
FUNCTION GetXML(a_tablela varchar2, a_key_1 varchar2, a_key_2 varchar2)
RETURN CLOB
is
x_xml CLOB;
BEGIN
select dbms_xmlgen.getxml('select * from '||a_tablela||' where key_1 = '''||a_key_1||''' and key_2 = '''||a_key_2||'''') into x_xml from dual;
return x_xml;
END;
BEGIN
--** TABLE_NAME Automatically fetches all columns and transforms them to CLOB
c_xml := GetXML('TABLE_NAME', :new.key_1, :new.key_2);
if c_xml is not null then
row_record.TABLE_NAME :=c_xml;
end if;
INSERT INTO NEW_TABLE VALUES row_record;
EXCEPTION
when others then
raise_application_error(-20000,'ERROR: '||to_char(sqlcode));
END;
Now I get error:
ORA-04091: table TABLE_NAME is mutating, trigger/function may not see it.
when I get this record across SELECT statement.
How do I convert row into CLOB in the applied TRIGGER AFTER UPDATE ?
Thanks.
The reason you can't use a select statement is because you're in the trigger, and the table is changing, or 'mutating', as the error says. The only way you can get the data from the row that's being updated here is using new and old:
old.column1
new.column1
Old being the value of the column before the update, new being the value after the update.
Example:
CREATE or REPLACE TRIGGER TRIGGER_NAME
AFTER UPDATE
ON TABLE_NAME
FOR EACH ROW
BEGIN
l_string := 'This is the old value for column 1: ' || old.column1 || '. This is the new value: ' || new.column1;
dbms_output.put_line(l_string);
END;
You won't be able to use dbms_xmlgen because it uses a select statement, which throws the mutating error exception.
I'm not sure I perfectly understand what you're trying to do, but you should be able to build the CLOB yourself just by concatenating yourself with the column names. Like this:
CREATE or REPLACE TRIGGER TRIGGER_NAME
AFTER UPDATE
ON TABLE_NAME
FOR EACH ROW
BEGIN
l_clob := 'Column1 ' || old.column1 || ', Column2 ' || old.column2; --For as many columns as are in the table
--Now you have a clob with all the old values, insert it where you want it
END;
And then go from there. If you really want the XML format you can do that yourself as well, just concatenate the strings together.