This code, works. It runs a row count the way you'd expect, I want to tweek it, mostly to do a count over a db_link for tables dictated as I see fit.
declare
n number;
begin
for i in (select table_name from user_tables) loop
execute immediate' select count(*) from '||i.table_name into n;
dbms_output.put_line('Table Name: '||i.table_name||' Count of Row''s: '||n);
end loop;
end;
/
So, this is the adapted code... it includes a variable with the name of the link. (The link works fine) But how to reference it is probably where I'm coming unstuck.
declare
l_dblink varchar2(100) := 'DB1';
n number;
begin
for i in (select table_name from my_tables) loop
execute immediate' select count(*) from '||i.table_name#||l_dblink into n;
dbms_output.put_line('Table Name: '||i.table_name||' Count of Row''s: '||n);
end loop;
end;
/
Can someone please have a look and tell me where I'm going wrong? I just want the SQL to pick up the table names from a local table, and then use the names to count the rows in those tables, which reside in the remote database.
Monkey is on the wrong tree and can't eat a banana.
SQL> create table my_tables (table_name varchar2(20));
Table created.
SQL> insert into my_tables values ('dual');
1 row created.
SQL> set serveroutput on
SQL> declare
2 l_dblink varchar2(100) := 'db1';
3 n number;
4 begin
5 for i in (select table_name from my_tables) -- has to be like this
6 loop -- vvv
7 execute immediate' select count(*) from '||i.table_name || '#' || l_dblink into n;
8 dbms_output.put_line('Table Name: '||i.table_name||' Count of Row''s: '||n);
9 end loop;
10 end;
11 /
Table Name: dual Count of Row's: 1
PL/SQL procedure successfully completed.
Related
I need a query that will get the column names of the result of another query. The other query can be anything - I can't make any assumptions about it but it will typically be some SELECT statement.
For example, if I have this table Members
Id | Name | Age
---|------|----
1 | John | 25
2 | Amir | 13
And this SELECT statement
SELECT Name, Age FROM Members
Then the result of the query I'm trying to write would be
Name
Age
In SQL Server, there is a function - sys.dm_exec_describe_first_result_set - that does this but I can't find an equivalent in Oracle.
I tried to use this answer but I can't use CREATE TYPE statements because of permissions issues and I probably can't use CREATE FUNCTION statements for the same reason.
Suppose you have a query like this:
select *
from (select deptno, job, sal from scott.emp)
pivot (avg(sal) as avg_sal for job in
('ANALYST' as analyst, 'CLERK' as clerk, 'SALESMAN' as salesman)
)
order by deptno
;
This produces the result:
DEPTNO ANALYST_AVG_SAL CLERK_AVG_SAL SALESMAN_AVG_SAL
---------- --------------- ------------- ----------------
10 1300
20 3000 950
30 950 1400
Notice the column names (like ANALYST_AVG_SAL) - they don't appear exactly in that form anywhere in the query! They are made up from two separate pieces, put together with an underscore.
Now, if you were allowed to create views (note that this does not create any data in your database - it just saves the text of a query), you could do this:
Create the view (just add the first line of code to what we already had):
create view q201028_vw as
select *
from (select deptno, job, sal from scott.emp)
pivot (avg(sal) as avg_sal for job in
('ANALYST' as analyst, 'CLERK' as clerk, 'SALESMAN' as salesman)
)
order by deptno
;
(Here I assumed you have some way to identify the query, an id like Q201028, and used that in the view name. That is not important, unless you need to do this often and for a large number of queries at the same time.)
Then you can find the column names (and also their order, and - if needed - their data type, etc.) by querying *_TAB_COLUMNS. For example:
select column_id, column_name
from user_tab_columns
where table_name = 'Q201028_VW'
order by column_id
;
COLUMN_ID COLUMN_NAME
---------- --------------------
1 DEPTNO
2 ANALYST_AVG_SAL
3 CLERK_AVG_SAL
4 SALESMAN_AVG_SAL
Now you can drop the view if you don't need it for anything else.
As an aside: The "usual" way to "save" queries in the database, in Oracle, is to create views. If they already exist as such in your DB, then all you need is the last step I showed you. Otherwise, were is the "other query" (for which you need to find the columns) coming from in the first place?
I would use the dbms_sql package and the following code example should show you how to start:
DECLARE
cursorID INTEGER;
status INTEGER;
colCount INTEGER;
rowCount INTEGER;
description dbms_sql.desc_tab;
colType INTEGER;
stringValue VARCHAR2(32676);
sqlCmd VARCHAR2(32767);
BEGIN
-- open cursor
cursorID := dbms_sql.open_cursor;
-- parse statement
dbms_sql.parse(cursorID, 'select * from user_tables', dbms_sql.native);
-- describe columns
dbms_sql.describe_columns(cursorID, colCount, description);
-- cursor close
dbms_sql.close_cursor(cursorID);
-- open cursor
cursorID := dbms_sql.open_cursor;
-- assemble a new select only using up to 5 the "text" columns
FOR i IN 1 .. description.COUNT LOOP
IF (i > 5) THEN
EXIT;
END IF;
IF (description(i).col_type IN (1, 112)) THEN
IF (sqlCmd IS NOT NULL) THEN
sqlCmd := sqlCmd || ', ';
END IF;
sqlCmd := sqlCmd || description(i).col_name;
END IF;
END LOOP;
sqlCmd := 'SELECT ' || sqlCmd || ' FROM user_tables';
dbms_output.put_line(sqlCmd);
-- parse statement
dbms_sql.parse(cursorID, sqlCmd, dbms_sql.native);
-- describe columns
dbms_sql.describe_columns(cursorID, colCount, description);
-- define columns
FOR i IN 1 .. description.COUNT LOOP
dbms_sql.define_column(cursorID, i, stringValue, 4000);
END LOOP;
-- execute
status := dbms_sql.execute(cursorID);
-- fetch up to 5 rows
rowCount := 0;
WHILE (dbms_sql.fetch_rows(cursorID) > 0) LOOP
rowCount := rowCount + 1;
IF (rowCount > 5) THEN
EXIT;
END IF;
dbms_output.put_line('row # ' || rowCount);
FOR i IN 1 .. description.COUNT LOOP
dbms_sql.column_value(cursorID, i, stringValue);
dbms_output.put_line('column "' || description(i).col_name || '" = "' || stringValue || '"');
END LOOP;
END LOOP;
-- cursor close
dbms_sql.close_cursor(cursorID);
END;
/
As astentx suggested, you can use a common table expression function to package the PL/SQL code into a SQL statement. This solution is just a single SQL statement, and requires no non-default privileges and does not create any permanent objects.
(The only downside is that not all SQL tools understand these kinds of WITH clauses, and they may throw an error expecting a different statement terminator.)
SQL> create table members(id number, name varchar2(100), age number);
Table created.
SQL> with function get_result_column_names(p_sql varchar2) return sys.odcivarchar2list is
2 v_cursor_id integer;
3 v_col_cnt integer;
4 v_columns dbms_sql.desc_tab;
5 v_column_names sys.odcivarchar2list := sys.odcivarchar2list();
6 begin
7 v_cursor_id := dbms_sql.open_cursor;
8 dbms_sql.parse(v_cursor_id, p_sql, dbms_sql.native);
9 dbms_sql.describe_columns(v_cursor_id, v_col_cnt, v_columns);
10
11 for i in 1 .. v_columns.count loop
12 v_column_names.extend;
13 v_column_names(v_column_names.count) := v_columns(i).col_name;
14 end loop;
15
16 dbms_sql.close_cursor(v_cursor_id);
17
18 return v_column_names;
19 exception when others then
20 dbms_sql.close_cursor(v_cursor_id);
21 raise;
22 end;
23 select *
24 from table(get_result_column_names(q'[select name, age from members]'));
25 /
COLUMN_VALUE
--------------------------------------------------------------------------------
NAME
AGE
Need your or guidance on how I can execute a select on multiple databases provided in the list. the goal behind this code is to query multiple remote databases and insert the output in current database.
Need to db_link to be fetched from a list or table
insert into xxxx.DB_tracker value(SELECT d.name FROM v$database#**opXXX_du**);
Dynamic SQL.
Suppose that database links are stored in the link table:
SQL> select * From links;
LINK
---------
dbl_ora10
dbl_ora11
dbl_orcl
You'd then use a loop, create an insert statement and execute it. As I don't have those database links, I'm just displaying statements to the screen. You'd uncomment the execute immediate line.
SQL> set serveroutput on
SQL> declare
2 l_str varchar2(200);
3 begin
4 for cur_r in (select link from links) loop
5 l_str := 'insert into db_tracker ' ||
6 'select name from v$database#' || cur_r.link;
7 dbms_output.put_line(l_str);
8
9 -- execute immediate l_str;
10 end loop;
11 end;
12 /
insert into db_tracker select name from v$database#dbl_ora10
insert into db_tracker select name from v$database#dbl_ora11
insert into db_tracker select name from v$database#dbl_orcl
PL/SQL procedure successfully completed.
SQL>
If you want to actually select name and display it on the screen, then you need the into clause. Something like this:
SQL> set serveroutput on
SQL>
SQL> declare
2 l_name varchar2(30);
3 begin
4 for cur_r in (select link from links) loop
5 execute immediate 'select name from v$database#' || cur_r.link
6 into l_name;
7 dbms_output.put_line(l_name);
8 end loop;
9 end;
10 /
XE
PL/SQL procedure successfully completed.
SQL>
my current sequence no is 203 i need to jump to 1203 without dropping the sequence.
First alter the sequence increment, given you stated 203 to 1203, I'm adding 1000, adjust as appropriate.
ALTER SEQUENCE yourSequence INCREMENT BY 1000;
Then request a value
SELECT yourSequence.NextVal FROM dual;
Then alter it back to incrementing by 1 (assuming it was 1 in the first place)
ALTER SEQUENCE yourSequence INCREMENT BY 1;
You really don't want to do this if the sequence is in active use - since it could jump up multiple thousands.
You may create such a procedure on your desired schema of DB as follows :
SQL>Create or Replace Procedure Pr_Set_Sequence( i_seq_name varchar2, i_val pls_integer ) is
v_val pls_integer;
begin
for c in (
Select u.sequence_name seq
From User_Sequences u
Where u.sequence_name = upper(i_seq_name)
)
loop
execute immediate 'select '||i_seq_name||'.nextval from dual' INTO v_val;
execute immediate 'alter sequence '||i_seq_name||' increment by ' ||
to_char(-v_val+i_val) || ' minvalue 0';
execute immediate 'select '||i_seq_name||'.nextval from dual' INTO v_val;
execute immediate 'alter sequence '||i_seq_name||' increment by 1 minvalue 0';
end loop;
end;
and call with the desired value ( in my case a create a new one called my_seq ) :
SQL> create sequence my_seq;
Sequence created
SQL> select my_seq.nextval from dual;
NEXTVAL
----------
1
SQL> begin
2 pr_set_sequence('my_seq',1203);
3 end;
4 /
PL/SQL procedure successfully completed
SQL> select my_seq.currval from dual;
NEXTVAL
----------
1203
Just do a WHILE loop, selecting from the sequence until it's up to the value you need. It's quite fast.
declare
v_sequence_value number;
begin
while v_sequence_value <= 1203 loop
select my_sequence.nextval into v_sequence_value from dual;
end loop;
end;
/
Lets assume, I have a string that holds a query string.
How can I select the rows from that query string in oracle ?
I tried execute immediate but it returns nothing.
declare
hello varchar(30000);
begin
hello:='select * from test_table';
execute immediate hello;
end;
You would use a dynamic cursor.
Here's an example with SQL*Plus:
SQL> var dyn_cur refcursor
SQL> DECLARE
2 l_sql_query VARCHAR2(1000);
3 BEGIN
4 -- complex function that returns a query:
5 l_sql_query := 'SELECT 1, dummy FROM dual';
6 OPEN :dyn_cur FOR l_sql_query;
7 END;
8 /
PL/SQL procedure successfully completed.
SQL> print dyn_cur
1 DUM
---------- ---
1 X
You can use dynamic cursors in PL/SQL procedures and packages:
SQL> CREATE OR REPLACE PROCEDURE prc_dyn_cur(p_dyn_cursor OUT SYS_REFCURSOR) IS
2 BEGIN
3 OPEN p_dyn_cursor FOR 'SELECT 1, dummy FROM dual';
4 END;
5 /
Procedure created.
SQL> exec prc_dyn_cur(:dyn_cur);
PL/SQL procedure successfully completed.
SQL> print dyn_cur
1 DUM
---------- ---
1 X
declare
hello varchar(30000);
type tb is table of test_table$rowtype;
mytb tb;
begin
hello:='select * from test_table';
execute immediate hello bulk collect into mytb;
-- now you got all og youe data in the "array" mytb
end;
notice that this solution takes into account that you know what table you are selecting from.
plus, i think you should describe what exactly it is you are trying to achieve.
CREATE OR REPLACE PROCEDURE query_executer (string_query IN VARCHAR)
IS
c1 SYS_REFCURSOR;
v_last_name employees.last_name%TYPE; -- Selecting last_name
BEGIN
OPEN c1 FOR string_query; -- Opening c1 for the select statement
LOOP
FETCH c1 INTO v_last_name;
DBMS_OUTPUT.put_line (v_last_name);
EXIT WHEN (C1%NOTFOUND);
END LOOP;
END;
SET SERVEROUTPUT ON
EXECUTE query_executer('select last_name from employees');
OUTPUT
Procedure created.
Abel
Ande
Atkinso
PL/SQL procedure successfully completed.
I am trying to write a very simple sql script:
select * from table_X;
and I would like to see the results in oracle sqlplus, if there are any. These results are important for further analysis.
Also to mention, it depends, how many tables were created originally, so chances are that table_X may not be in the database at all. However I want to avoid getting an error, when parsing, that table_X doesn't exist, while running that script above.
So I was trying to wrap that SQL into some PLSQL dynamic code, like this:
Define table_X="MY_TAB"
DECLARE
stmt_ VARCHAR2(2000);
exist_ number := 0;
CURSOR table_exist IS
SELECT 1
FROM user_tables
WHERE table_name = '&table_X';
BEGIN
OPEN table_exist;
FETCH table_exist INTO exist_;
CLOSE table_exist;
IF exist_ = 1 THEN
stmt_ := 'SELECT * FROM &table_X';
EXECUTE IMMEDIATE stmt_;
ELSE
dbms_output.put_line('This functionality is not installed.');
END IF;
END;
/
Why I cannot see any result (records), if there is data in MY_TAB? Do I really need to bind some columns and use ex. dbms_output to be able to see some information?
Is there any simple way to query a table without getting 'ORA-00942: table or view does not exist'
if that table doesn't exist (ideally using SQL only)?
Thanks in advance
like this if you want it in sqlplus:
SQL> var c refcursor;
SQL> create or replace function get_table(p_tab in varchar2)
2 return sys_refcursor
3 is
4 v_r sys_refcursor;
5 NO_TABLE exception;
6 pragma exception_init(NO_TABLE, -942);
7 begin
8 open v_r for 'select * from ' || dbms_assert.simple_sql_name(p_tab);
9 return v_r;
10 exception
11 when NO_TABLE
12 then
13 open v_r for select 'NO TABLE ' || p_tab as oops from dual;
14 return v_r;
15 end;
16 /
Function created.
SQL> exec :c := get_table('DUAL2');
PL/SQL procedure successfully completed.
SQL> print c
OOPS
-----------------------------------------
NO TABLE DUAL2
SQL>
SQL> exec :c := get_table('DUAL');
PL/SQL procedure successfully completed.
SQL> print c
D
-
X
Instead of execute immediate 'query' you could use execute immediate 'query' bulk collect into and then loop over it and use dbms_output to print it.
http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/executeimmediate_statement.htm