We have a sql script to update a set of sequences after seed data populated our tables. The code below would not work:
declare
cursor c1 is
select
'select nvl(max(id),0) from '||uc.table_name sql_text,
uc.table_name||'_SEQ' sequence_name
from
user_constraints uc,
user_cons_columns ucc
where uc.constraint_type='P'
and ucc.constraint_name = uc.constraint_name
and ucc.column_name='ID'
and uc.owner='ME';
alter_sequence_text varchar2(1024);
TYPE generic_cursor_type IS REF CURSOR;
max_id number;
c2 generic_cursor_type;
begin
for r1 in c1 loop
open c2 for r1.sql_text;
fetch c2 into max_id;
close c2;
if( max_id != 0 ) then
dbms_output.put_line( 'seq name = '||r1.sequence_name );
execute immediate 'alter sequence '||r1.sequence_name||' increment by '||to_char(max_id);
dbms_output.put_line( 'max_id = '||to_char(max_id) );
execute immediate 'select '||r1.sequence_name||'.nextval from dual';
dbms_output.put_line( 'sequence value = '||to_char(next_id) );
execute immediate 'alter sequence '||r1.sequence_name||' increment by 1';
dbms_output.put_line( 'sequence: '||r1.sequence_name||' is at '||to_char(max_id+1) );
end if;
end loop;
end;
After searching I found a reference that stated I needed to change the line:
execute immediate 'select '||r1.sequence_name||'.nextval from dual'
and add 'into next_id;' (of course declaring next_id appropriately) so the result would be:
execute immediate 'select '||r1.sequence_name||'.nextval from dual into next_id;
I've only dealt lightly with pl/sql and sql in general and am interested to know why this change was necessary to make the script work correctly.
Thanks.
When you are using select inside PL/SQL block you have to place data returned by that select statement somewhere. So you have to declare a variable of appropriate data type and use select into clause to put data select returns into that variable even if select statement is executed by execute immediate statement.
Examples
declare
x number;
begin
select count(*)
into x
from all_objects;
end;
declare
x number;
begin
execute immediate 'select count(*)from all_objects' into x;
end;
So your execute immediate statement would be
execute immediate 'select '||sequence_name||'.nextval from dual' into newseqval;
If you are using Oracle 11g onward you can assign sequence's value directly to a variable, there is no need of using select into clause.
declare
x number;
begin
x := Sequence_Name.nextval;
end;
select seq_name.nextval from dual implies the implicit cursor creation and the results of the cursor should be fetched somewhere so you need fetch it into any externally declared bind variable.
Related
Background
I'm trying to make a re-usable PL/SQL procedure to move data from one
database to another.
For this purpose, I'm using dynamic SQL.
The procedure executes perfectly if I use a REPLACE with placeholders.
However, for security reasons, I want to use bind variables.
Question
How can I make an entire PL/SQL code block dynamic (with bind
variables)? If I use a REPLACE instead of the bind variables, it works
fine.
How to replicate
To replicate this in your database, create the following procedure as it is:
create or replace procedure move_data(i_schema_name in varchar2, i_table_name in varchar2, i_destination in varchar2) as
l_sql varchar2(32767);
l_cursor_limit pls_integer := 500;
l_values_list varchar2(32767);
begin
select listagg('l_to_be_moved(i).' || column_name, ', ') within group (order by column_id)
into l_values_list
from all_tab_cols
where owner = i_schema_name and
table_name = i_table_name and
virtual_column = 'NO';
l_sql := q'[
declare
l_cur_limit pls_integer := :l_cursor_limit;
cursor c_get_to_be_moved is
select :i_table_name.*, :i_table_name.rowid
from :i_table_name;
type tab_to_be_moved is table of c_get_to_be_moved%rowtype;
l_to_be_moved tab_to_be_moved;
begin
open c_get_to_be_moved;
loop
fetch c_get_to_be_moved
bulk collect into l_to_be_moved limit l_cur_limit;
exit when l_to_be_moved.count = 0;
for i in 1.. l_to_be_moved.count loop
begin
insert into :i_table_name#:i_destination values (:l_values_list);
exception
when others then
dbms_output.put_line(sqlerrm);
l_to_be_moved.delete(i);
end;
end loop;
forall i in 1.. l_to_be_moved.count
delete
from :i_table_name
where rowid = l_to_be_moved(i).rowid;
for i in 1..l_to_be_moved.count loop
if (sql%bulk_rowcount(i) = 0) then
raise_application_error(-20001, 'Could not find ROWID to delete. Rolling back...');
end if;
end loop;
commit;
end loop;
close c_get_to_be_moved;
exception
when others then
rollback;
dbms_output.put_line(sqlerrm);
end;]';
execute immediate l_sql using l_cursor_limit, i_table_name, i_destination, l_values_list;
exception
when others then
rollback;
dbms_output.put_line(sqlerrm);
end;
/
And then you can execute the procedure with the following:
begin
move_data('MySchemaName', 'MyTableName', 'MyDatabaseLinkName');
end;
/
Due to many reasons(inability to generate an appropriate execution plan, security checking, etc.) Oracle does not allow identifiers binding (table names, schema names, column names and so on). So if it's really necessary, the only way is to hard code those identifiers after some sort of validation (to prevent SQL injection).
If I understand well, you could try a trick, by using a dynamic SQL inside a dynamic SQL.
setup:
create table tab100 as select level l from dual connect by level <= 100;
create table tab200 as select level l from dual connect by level <= 200;
create table tabDest as select * from tab100 where 1 = 2;
This will not work:
create or replace procedure testBind (pTableName in varchar2) is
vSQL varchar2(32000);
begin
vSQL := 'insert into tabDest select * from :tableName';
execute immediate vSQL using pTableName;
end;
But this will do the trick:
create or replace procedure testBind2 (pTableName in varchar2) is
vSQL varchar2(32000);
begin
vSQL := q'[declare
vTab varchar2(30) := :tableName;
vSQL2 varchar2(32000) := 'insert into tabDest select * from ' || vTab;
begin
execute immediate vSQL2;
end;
]';
execute immediate vSQL using pTableName;
end;
I think you can do it simpler.
create or replace procedure move_data(i_schema_name in varchar2, i_table_name in varchar2, i_destination in varchar2) as
l_sql varchar2(32767);
begin
select listagg('l_to_be_moved(i).' || column_name, ', ') within group (order by column_id)
into l_values_list
from all_tab_cols
where owner = i_schema_name and
table_name = i_table_name and
virtual_column = 'NO';
l_sql := 'insert into '||i_destination||'.'||i_table_name||' select * from '||i_schema_name||'.'||i_table_name;
execute immediate l_sql;
end;
If you are concerned about SQL-Injection, have a look at package DBMS_ASSERT. This PL/SQL package provides function to validate properties of input values.
I have a table A which has column A which holds table names as values.
All these tables have a common column C. I need maximum value of this column for each table.
I tried this using dynamic SQL but I'm getting errors. Please suggest.
DECLARE
query1 VARCHAR2(100);
c_table VARCHAR2(40);
c_obj VARCHAR2(20);
Cursor cursor_a IS
SELECT a FROM A;
BEGIN
Open cursor_a;
LOOP
Fetch cursor_a INTO c_table2;
EXIT WHEN cursor_a%notfound;
query1 := 'SELECT max(object_ref) AS "c_obj" FROM c_table' ;
EXECUTE IMMEDIATE query1;
dbms_output.put_line('Maximum value: '|| c_table || c_obj);
END LOOP;
Close cursor_a;
END;
Dynamic SQL can't see your PL/SQL variable: you need to pass it a string which can be executed in the scope of the SQL engine. So you need to concatenate the table name with the statement's boilerplate text:
query1 := 'SELECT max(c) FROM ' || variable_name;
You also need to return the result of the query into a variable.
Here is how it works (I've stripped out some of the unnecessary code from your example):
DECLARE
c_table VARCHAR2(40);
c_obj VARCHAR2(20);
BEGIN
for lrec in ( select a as tab_name from A )
LOOP
EXECUTE IMMEDIATE 'SELECT max(object_ref) FROM ' || lrec.tab_name
into c_obj ;
dbms_output.put_line('Maximum value: '|| lrec.tab_name
|| '='|| c_obj);
END LOOP;
END;
There is some miss match in veriables that you had used i.e.
declared as "c_table" but accessing as "c_table2"
Each table common column name is "C" but accessing as "object_ref"
In dynamic query use INTO keyword to store the value to your varibale
Suggestions
Use concat() function to prepare the query dynamically i.e. something like:
SET #SQL := CONCAT('SELECT max(c) INTO ', c_obj, ' FROM ',c_table);
Steps of implementing dynamic query is:
SET #SQL = <your dynamic query>
PREPARE stmt FROM #SQL;
EXECUTE stmt;
Sample code:
DECLARE
query1 VARCHAR2(100);
c_table VARCHAR2(40);
c_obj VARCHAR2(20);
CURSOR cursor_a IS
SELECT a FROM A;
BEGIN
OPEN cursor_a;
LOOP
FETCH cursor_a INTO c_table;
EXIT WHEN cursor_a%notfound;
SET #SQL := CONCAT('SELECT max(object_ref) AS c_obj INTO ', c_obj, ' FROM ',c_table);
PREPARE stmt FROM #SQL;
EXECUTE stmt;
dbms_output.put_line('Maximum value: '|| c_table || c_obj);
END LOOP;
CLOSE cursor_a;
END;
I need to create procedure which will delete all data from tables in one schema. I try something like that
CREATE OR REPLACE PROCEDURE CLEAR_ALL
IS
sql_truncate VARCHAR2(50);
cursor c1 is
SELECT table_name
FROM all_tables
WHERE owner = 'KARCHUDZ_S';
BEGIN
sql_truncate := 'TRUNCATE TABLE :text_string';
FOR table_name in c1
LOOP
EXECUTE IMMEDIATE sql_truncate USING table_name;
END LOOP;
END CLEAR_ALL;
But it gives me two errors which i cannot understand and fix.
Error(13,7): PL/SQL: Statement ignored
Error(13,44): PLS-00457: Statment must be type of SQL <-- (This error
i had to translate, cause i use University Oracle 11g base which have
Polish lang)
Why not just generate the statement and call it, like this?
CREATE OR REPLACE PROCEDURE CLEAR_ALL
IS
vs_statement VARCHAR2(100);
cursor c1 is
SELECT table_name
FROM all_tables
WHERE owner = 'KARCHUDZ_S';
BEGIN
FOR table_rec in c1
LOOP
vs_statement := 'TRUNCATE TABLE ' || table_rec.table_name;
EXECUTE IMMEDIATE vs_statement;
END LOOP;
END CLEAR_ALL;
You can't use bind variables (i.e. your using clause) as a placeholder for an object name. If you could, you wouldn't need to use dynamic SQL in the first place. You'll have to use concatenation or substitution instead:
CREATE OR REPLACE PROCEDURE CLEAR_ALL
IS
sql_truncate CONSTANT VARCHAR2(50) := 'TRUNCATE TABLE [text_string]';
cursor c1 is
SELECT table_name
FROM all_tables
WHERE owner = 'KARCHUDZ_S';
BEGIN
FOR row in c1
LOOP
EXECUTE IMMEDIATE replace(sql_truncate, '[text_string]', row.table_name);
END LOOP;
END CLEAR_ALL;
I am working on Oracle stored procedures.
My requirement is below
IF variable1 := 'true"
THEN
tableName=abr
ELSE
tableName=mvr
END IF;
FOR i IN (select unique(row1) as sc from tableName t where t.row2 = 'name') LOOP
BEGIN
-- required Logic
END
END LOOP;
But here I am not able to pass the table name in tableName parameter. How to do it?
You'll need to use Execute Immediate - it's designed for operations that aren't known until run time.
For normal operations, Oracle must know the tables and columns at compile time. You can't do SELECT * FROM tableName because it has no idea what tableName is and therefore it can't be compiled correctly.
Instead, you can do EXECUTE IMMEDIATE 'SELECT * FROM ' || tableName;
You can select your results INTO a variable, loop the result set, or BULK COLLECT into a structure and then iterate that.
For a simple select into, you can do this:
EXECUTE IMMEDIATE 'SELECT COL1, COL2 FROM ' || tableName INTO V_COL1, V_COL2
V_COL1 & V_COL2 are just local variables, tableName is a string representing your table name, and COL2 and COL2 are columns in the table you're selecting from. You can use the likes of ALL_TAB_COLUMNS to get the structure of a table dynamically.
Here is an example from Oracle docs:
CREATE OR REPLACE PROCEDURE query_invoice(
month VARCHAR2,
year VARCHAR2) IS
TYPE cur_typ IS REF CURSOR;
c cur_typ;
query_str VARCHAR2(200);
inv_num NUMBER;
inv_cust VARCHAR2(20);
inv_amt NUMBER;
BEGIN
query_str := 'SELECT num, cust, amt FROM inv_' || month ||'_'|| year
|| ' WHERE invnum = :id';
OPEN c FOR query_str USING inv_num;
LOOP
FETCH c INTO inv_num, inv_cust, inv_amt;
EXIT WHEN c%NOTFOUND;
-- process row here
END LOOP;
CLOSE c;
END;
/
http://docs.oracle.com/cd/B12037_01/appdev.101/b10795/adfns_dy.htm
You are going to have to build a for loop for each table then use your logic to determine which loop you will execute.
I need a help on this.
I am trying to create a pl/sql anonymous block and when I run that it shows its completed but it don't run the code. It should give me an error saying name is already used by an existing object. Can someone help me on this.
I am actually creating procedures but just trying this code as a sample.
DECLARE
V_REF_TBL VARCHAR2(100);
V_SQL LONG;
begin
V_REF_TBL :='My_TABLE';
v_SQL :='truncate table '||V_REF_TBL ;
EXECUTE IMMEDIATE V_SQL;
EXECUTE IMMEDIATE 'CREATE TABLE '|| V_REF_TBL ||' parallel 9 nologging pctfree 0 as
select * from dual';
End;
Possibly you're looking for this:
<<my_block>>
Declare
table_name varchar2(30);
counter number;
Begin
table_name := 'my_table';
select count(*)
into counter
from user_tables
where table_name = Upper(Trim(my_block.table_name)) and
dropped = 'NO';
if counter = 0
then
execute immediate 'create table '||table_name||' as ... etc';
else
execute immediate 'truncate table '||table_name;
execute immediate 'insert into '||table_name' select ... etc';
end if;
end my_block;