Let's say I've got two tables t1 and t2, and I'm inserting data into t1 using columns selected from t2.
create or replace package body for_update_test
as
procedure test(out_response out varchar2) as
v_id number;
begin
select id into v_id from t2 where id = 1 for update;
insert into t1
(
id
)
select
id
from
t2
where
id = 1
;
out_response:= 'success';
end test;
end for_update_test;
/
The above works, but is there a way to combine the insert-select with for update, something like (it obviously does not work, so wondering if it's just the syntax I am not getting right or if it's not supported):
create or replace package body for_update_test
as
procedure test(out_response out varchar2) as
v_id number;
begin
insert into t1
(
id
)
select
id
from
t2
where
id = 1
for update
;
out_response:= 'success';
end test;
end for_update_test;
/
Here's what I am trying to achieve: select data from a table (t2 here), modify the values, then insert into its gtt twin (t1 here). Then, the gtt data will be applied back into the actual table itself. The for update during the initial selection from t2 ensures the data written back to it eventually through t1 doesn't accidentally overwrite data written by a different procedure that also modifies (different columns) this way.
Way convoluted than it should be this being a legacy routine, but I've got very little leeway right now to change the whole design (like not having to go through GTT), so just locking the original table for updates to do controlled changes.
Related
So I usually get the Primary Key of a newly inserted record as the following while using a trigger.
insert into table1 (pk1, notes) values (null, "Tester") returning pk1
into v_item;
I am trying to use the same concept but with an insert using a select statement. So for example:
insert into table1 (pk1, notes) select null, description from table2 where pk2 = 2 returning pk1
into v_item;
Note:
1. There is a trigger on table1 which automatically creates a pk1 on insert.
2. I need to use a select insert because of the size of the table that is being inserted into.
3. The insert is basically a copy of the record, so there is only 1 record being inserted at a time.
Let me know if I can provide more information.
I don't believe you can do this with insert/select directly. However, you can do it with PL/SQL and FORALL. Given the constraint about the table size, you'll have to balance memory usage with performance using l_limit. Here's an example...
Given this table with 100 rows:
create table t (
c number generated by default as identity,
c2 number
);
insert into t (c2)
select rownum
from dual
connect by rownum <= 100;
You can do this:
declare
cursor t_cur
is
select c2
from t;
type t_ntt is table of number;
l_c2_vals_in t_ntt;
l_c_vals_out t_ntt;
l_limit number := 10;
begin
open t_cur;
loop
fetch t_cur bulk collect into l_c2_vals_in limit l_limit;
forall i in indices of l_c2_vals_in
insert into t (c2) values (l_c2_vals_in(i))
returning c bulk collect into l_c_vals_out;
-- You have access to the new ids here
dbms_output.put_line(l_c_vals_out.count);
exit when l_c2_vals_in.count < l_limit;
end loop;
close t_cur;
end;
You can't use that mechanism; as shown in the documentation railroad diagram:
the returning clause is only allowed with the values version, not with the subquery version.
I'm interpreting your second restriction (about 'table size') as being about the number of columns you would have to handle, possibly as individual variables, rather than about the number of rows - I don't see how that would be relevant here. There are ways to avoid having lots of per-column local variables though; you could select into a row-type variable first:
declare
v_item number;
v_row table1%rowtype;
begin
...
select null, description
into v_row
from table2 where pk2 = 2;
insert into table1 values v_row returning pk1 into v_item;
dbms_output.put_line(v_item);
...
or with a loop, which might make things look more complicated than necessary if you really only ever have a single row:
declare
v_item number;
begin
...
for r in (
select description
from table2 where pk2 = 2
)
loop
insert into table1 (notes) values (r.description) returning pk1 into v_item;
dbms_output.put_line(v_item);
...
end loop;
...
or with a collection... as #Dan has posted while I was answering this so I won't repeat! - though again that might be overkill or overly complicated for a single row.
I need this piece of code in a stored procedure so I can pass an array of ids and update the related records. I am wondering whether I have to use the loop rather than use an IN clause in the sp.
SET SERVEROUTPUT ON
DECLARE
P_IDS PKGINFO.t_ids; --type: table of NUMBER index by pls_integer;
P_RESULT NUMBER;
BEGIN
p_IDS(1) := 12345;
--this works fine:
for i in ( select * from table(p_ids))
loop
UPDATE TABLE1
SET FD1 = 'test'
WHERE P_ID = i.column_value;
end loop;
--this works fine too:
SELECT COUNT(*) INTO p_RESULT FROM TABLE1
WHERE P_ID IN (SELECT * FROM TABLE (p_ids));
--but this does not work, why????? how to make it work?
UPDATE TABLE1
SET FD1 = 'test'
WHERE P_ID IN (SELECT * FROM TABLE (p_ids));
END;
--==================PKGINFO.t_ids==================
CREATE OR REPLACE package dbname.PKGINFO as
-- package created to perform Associative array calls
type t_ids is table of NUMBER index by pls_integer;
end PKGINFO;
/
I expected the UPDATE can use IN clause, but it gives me an INVALID TYPE error.
Until fairly recently Oracle didn't allow PL/SQL types in SQL statements, including in a table collection expression. You seem to be using a version where support has been added for select but not (yet) for update. If you had one available then you could use a schema-level type. Also have a look at member of.
With the type you have now you could use FORALL, which would be more efficient than a loop with individual updates::
FORALL i IN p_ids.first..p_ids.last
UPDATE TABLE1
SET FD1 = 'test'
WHERE P_ID = p_ids(i);
I want to create a procedure in PL/SQL that has 5 steps. Step 1 and 2 execute first and return an ID. In step 3, we have a SELECT statement that has a condition with that returned ID. I want then to take all of the results of that SELECT statement and use them in a JOIN in another SELECT statement and use THOSE results in a 3rd SELECT statement again using JOIN. From what I've seen, I can't use CURSOR in JOIN statements. Some of my co-workers have suggested that I save the results in a CURSOR and then use a loop to iterate through each row and use that data for the next SELECT. However since I'm going to do 2 selects this will create a huge fork of inside loops and that's exactly what I'm trying to avoid.
Another suggestion was to use Temprary Tables to store the data. However this procedure could be executed at the same time by many users and the table's data would conflict with each other. Right now I'm looking at LOCAL Temporary tables that supposedly filter the data according the the session but I'm not really sure I want to create dummy tables for my procedures since I want to avoid leaving trash in the schema (this procedure is for a custom part of the application). Is there a standard way of doing this? Any ideas?
Sample:
DECLARE
USERID INT := 1000000;
TEXT1 VARCHAR(100);
TEXT_INDEX INT;
CURSOR NODES IS SELECT * FROM NODE_TABLE WHERE DESCRIPTION LIKE TEXT || '%';
CURSOR USERS IS SELECT * FROM USERGROUPS JOIN NODES ON NODES.ID = USERGROUPS.ID;
BEGIN
SELECT TEXT INTO TEXT1 FROM TABLE_1 WHERE ID = USERID;
TEXT_INDEX = INSTR(TEXT, '-');
TEXT = SUBSTR(TEXT, 0, TEXT_INDEX);
OPEN NODES;
OPEN USERS;
END;
NOTE: This does NOT work. Oracle doesn't support joins between cursors.
NOTE2: This CAN be done in a single query but for the sake of argument (and in my real use case) I want to break those steps down in a procedure. The sample code is a depiction of what I'm trying to achieve IF joins between cursors worked. But they don't and I'm looking for an alternative.
I ended up using a function (although a procedure could be used as well) along with tables. Things I've learned and one should pay attention to:
PL/SQL functions can only return types that have been declared in the schema in advance and are clear. You can't create a function that returns something like MY_TABLE%ROWTYPE, even though it seems the type information is available it is not acceptable. You have to instead create a custom type of MY_TABLE%ROWTYPE is you want to return it.
Oracle treats tables of declared types differently from tables of %ROWTYPE. This confused the hell out of me at first but from what I've gathered this is how it works.
DECLARE TYPE MY_CUSTOM_TABLE IS TABLE OF MY_TABLE%ROWTYPE;
Declares a collection of types of MY_TABLE row. In order to add to this we must use BULK COLLECT INTO from an SQL statement that queries MY_TABLE. The resulting collection CANNOT be used in JOIN statements is not queryable and CANNOT be returned by a function.
DECLARE
CREATE TYPE MY_CUSTOM_TYPE AS OBJECT (COL_A NUMBER, COL_B NUMBER);
CREATE TYPE MY_CUSTOM_TABLE AS TABLE OF MY_CUSTOM_TYPE;
my_custom_tab MY_CUSTOM_TABLE;
This create my_custom_tab which is a table (not a collection) and if populated can be queried at using TABLE(my_custmo_tab) in the FROM statement. As a table which is declared in advance in the schema this CAN be returned from a function. However it CANNOT be populated using BULK COLLECT INTO since it is not a collection. We must instead use the normal SELECT INTO statement. However, if we want to populate it with data from an existing table that has 2 number columns we cannot simply do SELECT * INTO my_custom_tab FROM DOUBLE_NUMBER_TABLE since my_custom_tab hasn't been initialized and doesn't contain enough rows to receive the data. And if we don't know how many rows a query returns we can't initialize it. The trick into populating the table is to use the CAST command and cast our select result set as a MY_CUSTOM_TABLE and THEN add it.
SELECT CAST(MULTISET(SELECT COL_A, COL_B FROM DOUBLE_NUMBER_TABLE) AS MY_CUSTOM_TABLE) INTO my_custom_tab FROM DUAL
Now we can easily use my_custom_tab in queries etc through the use of the TABLE() function.
SELECT * FROM TABLE(my_custom_tab)
is valid.
You can do such decomposition in many ways, but all of them have a significant performance penalty in comaration with single SQL statement.
Maintainability improvement are also questionable and depends on specific situation.
To review all possibilities please look through documentation.
Below is some possible variants based on simple logic:
calculate Oracle user name prefix based on given Id;
get all users whose name starts with this prefix;
find all tables owned by users from step 2;
count a total number of found tables.
1. pipelined
Prepare types to be used by functions:
create or replace type TUserRow as object (
username varchar2(30),
user_id number,
created date
)
/
create or replace type TTableRow as object (
owner varchar2(30),
table_name varchar2(30),
status varchar2(8),
logging varchar2(3)
-- some other useful fields here
)
/
create or replace type TUserList as table of TUserRow
/
create or replace type TTableList as table of TTableRow
/
Simple function to find prefix by user id:
create or replace function GetUserPrefix(piUserId in number) return varchar2
is
vUserPrefix varchar2(30);
begin
select substr(username,1,3) into vUserPrefix
from all_users
where user_id = piUserId;
return vUserPrefix;
end;
/
Function searching for users:
create or replace function GetUsersPipe(
piNameStart in varchar2
)
return TUserList pipelined
as
vUserList TUserList;
begin
for cUsers in (
select *
from
all_users
where
username like piNameStart||'%'
)
loop
pipe row( TUserRow(cUsers.username, cUsers.user_id, cUsers.created) ) ;
end loop;
return;
end;
Function searching for tables:
create or replace function GetUserTablesPipe(
piUserNameStart in varchar2
)
return TTableList pipelined
as
vTableList TTableList;
begin
for cTables in (
select *
from
all_tables tab_list,
table(GetUsersPipe(piUserNameStart)) user_list
where
tab_list.owner = user_list.username
)
loop
pipe row ( TTableRow(cTables.owner, cTables.table_name, cTables.status, cTables.logging) );
end loop;
return;
end;
Usage in code:
declare
vUserId number := 5;
vTableCount number;
begin
select count(1) into vTableCount
from table(GetUserTablesPipe(GetUserPrefix(vUserId)));
dbms_output.put_line('Users with name started with "'||GetUserPrefix(vUserId)||'" owns '||vTableCount||' tables');
end;
2. Simple table functions
This solution use same types as a variant with pipelined functions above.
Function searching for users:
create or replace function GetUsers(piNameStart in varchar2) return TUserList
as
vUserList TUserList;
begin
select TUserRow(username, user_id, created)
bulk collect into vUserList
from
all_users
where
username like piNameStart||'%'
;
return vUserList;
end;
/
Function searching for tables:
create or replace function GetUserTables(piUserNameStart in varchar2) return TTableList
as
vTableList TTableList;
begin
select TTableRow(owner, table_name, status, logging)
bulk collect into vTableList
from
all_tables tab_list,
table(GetUsers(piUserNameStart)) user_list
where
tab_list.owner = user_list.username
;
return vTableList;
end;
/
Usage in code:
declare
vUserId number := 5;
vTableCount number;
begin
select count(1) into vTableCount
from table(GetUserTables(GetUserPrefix(vUserId)));
dbms_output.put_line('Users with name started with "'||GetUserPrefix(vUserId)||'" owns '||vTableCount||' tables');
end;
3. cursor - xml - cursor
It's is a specific case, which may be implemented without user-defined types but have a big performance penalty, involves unneeded type conversion and have a low maintainability.
Function searching for users:
create or replace function GetUsersRef(
piNameStart in varchar2
)
return sys_refcursor
as
cUserList sys_refcursor;
begin
open cUserList for
select * from all_users
where username like piNameStart||'%'
;
return cUserList;
end;
Function searching for tables:
create or replace function GetUserTablesRef(
piUserNameStart in varchar2
)
return sys_refcursor
as
cTableList sys_refcursor;
begin
open cTableList for
select
tab_list.*
from
(
XMLTable('/ROWSET/ROW'
passing xmltype(GetUsersRef(piUserNameStart))
columns
username varchar2(30) path '/ROW/USERNAME'
)
) user_list,
all_tables tab_list
where
tab_list.owner = user_list.username
;
return cTableList;
end;
Usage in code:
declare
vUserId number := 5;
vTableCount number;
begin
select count(1) into vTableCount
from
XMLTable('/ROWSET/ROW'
passing xmltype(GetUserTablesRef(GetUserPrefix(vUserId)))
columns
table_name varchar2(30) path '/ROW/TABLE_NAME'
)
;
dbms_output.put_line('Users with name started with "'||GetUserPrefix(vUserId)||'" owns '||vTableCount||' tables');
end;
Of course, all variants may be mixed, but SQL looks better at least for simple cases:
declare
vUserId number := 5;
vUserPrefix varchar2(100);
vTableCount number;
begin
-- Construct prefix from Id
select max(substr(user_list.username,1,3))
into vUserPrefix
from
all_users user_list
where
user_list.user_id = vUserId
;
-- Count number of tables owned by users with name started with vUserPrefix string
select
count(1) into vTableCount
from
all_users user_list,
all_tables table_list
where
user_list.username like vUserPrefix||'%'
and
table_list.owner = user_list.username
;
dbms_output.put_line('Users with name started with "'||vUserPrefix||'" owns '||vTableCount||' tables');
end;
P.S. All code only for demonstration purposes: no optimizations and so on.
I'm relatively new to PL/SQL, so please bear with me.
I'm creating two tables that will be used in the FOR loop cursor. My intention was to create these two tables at the start (before the cursor loop), truncate them inside the cursor loop whenever I need it cleared and insert new values, then drop them at after the cursor loop completes.
(After looking a bit on SO, I think this can be done with REF CURSOR, but I'm not very clear on how to use that so I decided to go ahead with the first approach.)
I tried creating the tables in the DECLARE section, then in the BEGIN section before the loop starts, but it raises the error 'ORA-065500 and PLS-00103 Encountered the symbol CREATE when expecting begin function pragma ...'
Note that I am dropping the tables after the LOOP ends but before the END section of the cursor.
Should I create the tables outside the cursor , before the DECLARE section, and drop them after the cursor END section? I thought it should be possible to create permanent oracle tables inside cursors?
Update: Posting code here-
1)
DECLARE
CREATE TABLE T1
(
col1 VARCHAR2(128),
col2 VARCHAR2(128),
col3 NUMBER(3) NOT NULL,
col3 FLOAT(100)
);
CREATE TABLE T2 AS
SELECT * FROM other_table WHERE 1 = 0;
CURSOR CUR IS ...
BEGIN
FOR rec IN CUR
LOOP
--Do stuff here
END LOOP;
Drop table T1;
Drop table T2;
END;
/
2)
DECLARE
CURSOR CUR IS ...
BEGIN
CREATE TABLE T1
(
col1 VARCHAR2(128),
col2 VARCHAR2(128),
col3 NUMBER(3) NOT NULL,
col3 FLOAT(100)
);
CREATE TABLE T2 AS
SELECT * FROM other_table WHERE 1 = 0;
FOR rec IN CUR
LOOP
--Do stuff here
END LOOP;
Drop table T1;
Drop table T2;
END;
/
(1) and (2) both don't work.
Update- Do we need EXECUTE IMMEDIATE for this? How do I know when I need EXECUTE IMMEDIATE? Do we also need EXECUTE IMMEDIATE for truncating tables in cursors?
Usually you don't perform DDLs (create, alter, drop) inside your PL/SQL procedure. If you need a table to store some temporary data, you can create temporary tables for this purpose. In your case I would first create the tables
CREATE GLOBAL TEMPORARY TABLE T1
(
col1 VARCHAR2(128),
col2 VARCHAR2(128),
col3 NUMBER(3) NOT NULL,
col3 FLOAT(100)
);
CREATE GLOBAL TEMPORARY TABLE T2 AS
SELECT * FROM other_table WHERE 1 = 0;
And then the procedure would look like this
DECLARE
CURSOR CUR IS ...
BEGIN
FOR rec IN CUR
LOOP
--Do stuff here
END LOOP;
DELETE FROM T1;
DELETE FROM T2;
END;
/
Of course the tables would not be dropped after that, but I suppose you want to use your PL/SQL procedure regularly, not only once, right?
If you still want to peform DDL in your procedure, then you must use dynamic sql (execute immediate). However you have to be aware that DDL operations perform implicit commits, so your procedure would not be a single atomic transaction.
I want to be able to delete by rowid then immediately insert the data being deleted in an audit table.
There are far too many records to
INSERT INTO ... SELECT CRITERIA then DELETE ... CRITERIA.
I already know how to do everything just using rowid and INSERT INTO ... SELECT.
Inside package body:
TYPE some_type IS RECORD (
row_id ROWID,
full_row table_name%ROWTYPE
);
TYPE some_type_list IS TABLE OF some_type
INDEX BY BINARY_INTEGER;
PROCEDURE do_stuff
IS
lc_data SYS_REFCURSOR;
lt_recs some_type_list;
BEGIN
OPEN lc_date FOR
SELECT rowid, a.*
FROM table_name;
LOOP
FETCH lc_data
BULK COLLECT INTO lt_recs
LIMIT 50000;
EXIT WHEN lt_recs.COUNT = 0;
--
FORALL i IN lt_recs.FIRST..lt_recs.LAST
DELETE table_name
WHERE ROWID = lt_recs(i).row_id;
--
FORALL i IN lt_recs.FIRST..lt_recs.LAST
INSERT INTO table_name_audit VALUES lt_recs(i).full_row;
END LOOP;
END;
If I try that i get the following error:
Line: 117 Column: 25 Type: error Text: PLS-00597: expression 'LT_RECS' in the INTO list is of wrong type
Oracle versions prior to 11gR2 restrict us to use BULK COLLECT into a collection (nested table or varray) of records. Read more here on Oracle Docs.
If you want to see how it is done in 11gR2, scroll down to EDIT 2 section of this answer.
An alternative tho this can be the use of separate collections for every column- an approach that is most widely used. In this you can have:
/*
TYPE some_type IS RECORD (
row_id ROWID,
full_row table_name%ROWTYPE
);
TYPE some_type_list IS TABLE OF some_type
INDEX BY BINARY_INTEGER;
-- */
CREATE TYPE t_row_id IS TABLE OF ROWID;
CREATE TYPE t_col1 IS TABLE OF table_name.col1%TYPE;
CREATE TYPE t_col2 IS TABLE OF table_name.col2%TYPE;
CREATE TYPE t_col3 IS TABLE OF table_name.col3%TYPE;
...
...
CREATE TYPE t_colN IS TABLE OF table_name.colN%TYPE;
PROCEDURE do_stuff
IS
lc_data SYS_REFCURSOR;
-- lt_recs some_type_list;
row_id t_row_id;
col1 t_col1;
col2 t_col2;
col3 t_col3;
...
...
colN t_colN;
BEGIN
OPEN lc_date FOR
SELECT rowid, a.*
FROM table_name;
LOOP
FETCH lc_data
BULK COLLECT INTO row_id, col1, col2, col3, ..., colN
LIMIT 50000;
EXIT WHEN lt_recs.COUNT = 0;
--
FORALL i IN row_id.FIRST..row_id.LAST
DELETE table_name
WHERE ROWID = row_id(i);
--
FORALL i IN col1.FIRST..col1.LAST
INSERT INTO table_name_audit VALUES (col1(i), col2(i), col3(i), ..., colN(i));
END LOOP;
END;
I have not removed many of the rows in your program in order to let you understand the changes.
EDIT : Refer to the "Restrictions on BULK COLLECT" section of the Oracle Docs link I have given above and also here.
EDIT #2 :
You have to use CREATE TYPE ... IS OBJECT instead of RECORD. Also, You need to modify the SELECT statement the way I have done when I tried it. Please see the Oracle Docs here and a StackOverflow question here for further reference.
The code I tried on my machine (runs Oracle 11g R2) is as follows:
-- SELECT * FROM user_objects WHERE object_type = 'TYPE';
CLEAR SCREEN;
SET SERVEROUTPUT ON;
CREATE OR REPLACE TYPE temp_t_test AS OBJECT ( -- << OBJECT, not RECORD.
test_id INTEGER
, test_val VARCHAR2(50)
);
/
CREATE OR REPLACE TYPE temp_tbl_test AS TABLE OF TEMP_T_TEST;
/
DECLARE
v_test TEMP_TBL_TEST;
BEGIN
SELECT temp_t_test(t_id, t_val) -- << Notice the syntax
-- I'm selecting the columns as the defined OBJECT type.
BULK COLLECT INTO v_test
FROM (SELECT 1 AS t_id, 'ABCD' AS t_val FROM dual
UNION ALL
SELECT 2, 'WXYZ' FROM dual
UNION ALL
SELECT 3, 'PQRS' FROM dual);
dbms_output.put_line('Bulk Collect Successful!');
END;
/
** OUTPUT **:
TYPE temp_t_test compiled
TYPE temp_tbl_test compiled
anonymous block completed
Bulk Collect Successful!
I don't think that I'd take this approach at all, to be honest.
A faster method would be along the lines of performing a multitable insert:
insert the table columns into the audit table, possibly using direct path (APPEND hint) for efficiency
insert the rowid's into an on-commit-delete-rows global temporary table.
Then perform a delete against the original table using DELETE .. WHERE ROWID IN (SELECT ORIGINAL_ROWID FROM MY_GLOBAL_TEMP_TAB)
... and then commit.
Faster, and less code I think.
What you're trying to works in 11gR2 - what version are you on?.
The only wrong-looking thing in your post is this:
OPEN lc_date FOR
SELECT rowid, a.*
FROM table_name;
It ought to be this ...
OPEN lc_data FOR
SELECT a.rowid, a.*
FROM table_name a;
... but these may simply be typos you introduced when sanitizing your code to post here.