Is it possible to pass a table name to a query using a result of another query?
SELECT T.MID, T.TID, M.NAME
FROM 'ONLINETRANSACTION#(' || SELECT ONLINEDBLINK FROM PARAMETERTABLE ||')' T
LEFT JOIN 'ONLINEMERCHANT#(' || SELECT ONLINEDBLINK FROM PARAMETERTABLE ||')' M
ON T.MID = M.MID
I have tried with the above code but it doesn't work.
This is a simple example based on Scott's schema.
lines 5 - 7 select your "table name" (actually, it appears that it is a database link name in your code. Doesn't matter, the principle is just the same)
line 9 uses that "table name" and concatenates it with the rest of the SELECT statement; finally, it executes it using EXECUTE IMMEDIATE
SQL> create table param (table_name varchar2(30));
Table created.
SQL> insert into param values ('EMP');
1 row created.
SQL> set serveroutput on
SQL> declare
2 l_table_name param.table_name%type;
3 l_max_sal emp.sal%type;
4 begin
5 select table_name into l_table_name
6 from param
7 where rownum = 1;
8
9 execute immediate 'select max(sal) from ' || l_table_name into l_max_sal;
10 dbms_output.put_line('Max salary = ' || l_max_sal);
11 end;
12 /
Max salary = 10000
PL/SQL procedure successfully completed.
SQL>
Related
I have a huge database with 400+ tables. Each table has the same column id for the Primary key and "timestamp_modify" in which the last change of the table is done.
So what I want are 2 things:
Now I want a list of all changes by ID and table name like:
Table | id | timestamp_modiy
Kid | 1 | 24.10.2021 00:01
Parent | 1000 | 24.10.2021 00:02
The only, very bad way I could come up with, is that I make a view in which I include every damn table by hand and read out the values...
Is there a better way?
How about a pipelined function?
Just setting datetime format (you don't have to do that):
SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi:ss';
Session altered.
Types:
SQL> create or replace type t_row as object
2 (table_name varchar2(30),
3 id number,
4 timestamp_modify date)
5 /
Type created.
SQL> create or replace type t_tab is table of t_row;
2 /
Type created.
Function: querying user_tab_columns, its cursor FOR loop fetches tables that contain both ID and TIMESTAMP_MODIFY columns, dynamically creates select statement to return the last (MAX function, to avoid too_many_rows) columns' values for the last TIMESTAMP_MODIFY value (returned by the subquery).
SQL> create or replace function f_test
2 return t_tab pipelined
3 as
4 l_str varchar2(500);
5 l_id number;
6 l_timestamp_modify date;
7 begin
8 for cur_r in (select table_name from user_tab_columns
9 where column_name = 'ID'
10 intersect
11 select table_name from user_tab_columns
12 where column_name = 'TIMESTAMP_MODIFY'
13 )
14 loop
15 l_str := 'select max(a.id) id, max(a.timestamp_modify) timestamp_modify ' ||
16 'from ' || cur_r.table_name || ' a ' ||
17 'where a.timestamp_modify = ' ||
18 ' (select max(b.timestamp_modify) ' ||
19 ' from ' || cur_r.table_name || ' b ' ||
20 ' where b.id = a.id)';
21 execute immediate l_str into l_id, l_timestamp_modify;
22 pipe row(t_row(cur_r.table_name, l_id, l_timestamp_modify));
23 end loop;
24 end;
25 /
Function created.
Testing:
SQL> select * from table(f_test);
TABLE_NAME ID TIMESTAMP_MODIFY
------------------------------ ---------- -------------------
TABA 1 24.10.2021 14:59:29
TAB_1 1 24.10.2021 15:03:16
TAB_2 25 24.10.2021 15:03:36
TEST 5 24.10.2021 15:04:24
SQL>
Yes, the only way is to union all all tables, like:
select id, timestamp_modify
from kid
union all
select id, timestamp_modify
from parent
union all
...
The performance will be awful, since all the tables will be scanned every time :(
I think that you might reconsider you db design...
You can build a procedure for this, but even so it will have some impact in performance. Although there is a loop, with SQL Dynamic, you might only need 400 iterations, and in each one you will insert all the ids of that table.
I am taking some assumptions
You want all the IDs and their corresponding timestamp_modify per table
I create a table to store the results. If you use it with the same name always it will recycle the object. If you not, you can keep a history
I am assuming that only one timestamp_modify row is present per ID
I filter only the tables of your schema that contain both columns.
The table contains also the table_name that you can identify where the record is coming from.
One example
create or replace procedure pr_build_output ( p_tmp_table in varchar2 default 'TMP_RESULT' )
is
vcounter pls_integer;
vsql clob;
vtimestamp date; -- or timestamp
begin
-- create table to store results
select count(*) into vcounter from all_tables where table_name = upper(p_tmp_table) and owner = 'MY_SCHEMA';
if vcounter = 1
then
execute immediate ' drop table '||p_tmp_table||' purge ' ;
end if;
vsql := ' create table '||p_tmp_table||'
( table_name varchar2(128) ,
id number,
timestamp_modify date -- or timestamp
) ';
execute immediate vsql ;
-- Populate rows
for h in
( select a.table_name from all_tables a
where a.owner = 'MY_SCHEMA'
and a.table_name in ( select distinct b.table_name from all_tab_columns b where b.owner = 'MY_SCHEMA'
and b.column_name = 'ID' and b.column_name = 'TIMESTAMP_MODIFY'
)
)
loop
vsql := ' insert into '||p_tmp_table||' ( table_name , id, timestamp_modify )
select '''||h.table_name||''' as table_name , id , timestamp_modify
from my_schema.'||h.table_name||'
' ;
execute immediate vsql ;
commit ;
end loop;
exception when others then raise;
end;
/
I'm trying to move rows between two tables which have many columns.
The table columns are identical other than the destination table (tab#db2) has a few more columns which causes a simple INSERT to fail.
I'd like to use a simple PL/SQL statement to build a list of the columns in tab#db2 dynamically instead of typing out the names of col1, col2, etc in the INSERT and SELECT clause. Example
declare a variable as var_col_list
set col_list = output of select * from tab (omitting rows)
INSERT INTO TAB *var_col_list* SELECT *var_cols_list* FROM TABLE TAB#db2
I've researched using %rowtype but cannot find a suitable example that would take less time than simply writing out the names of the columns!
Any advice is greatly appreciated
If you use e.g. TOAD, you can right-click the table and let it Generate statement - in your case, that would be INSERT. You'd slightly modify it (remove columns you don't need) and that's all.
Otherwise, this is how you might do it semi-manually.
This is my source table:
SQL> SELECT * FROM dept;
DEPTNO DNAME LOC
---------- -------------------- --------------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
Target table doesn't contain all columns:
SQL> CREATE TABLE target
2 (
3 deptno NUMBER,
4 dname VARCHAR2 (20)
5 );
Table created.
Code which loops through all TARGET table columns (i.e. a table which has less columns) and composes the INSERT INTO statement:
SQL> DECLARE
2 l_str VARCHAR2 (1000);
3 BEGIN
4 FOR cur_r IN (SELECT column_name
5 FROM user_tab_columns
6 WHERE table_name = 'TARGET')
7 LOOP
8 l_str := l_str || ', ' || cur_r.column_name;
9 END LOOP;
10
11 l_str :=
12 'insert into target select ' || LTRIM (l_str, ', ') || ' from dept';
13 DBMS_OUTPUT.put_line (l_str);
14
15 EXECUTE IMMEDIATE l_str;
16 END;
17 /
insert into target select DEPTNO, DNAME from dept --> this is the L_STR contents
PL/SQL procedure successfully completed.
SQL> SELECT * FROM target;
DEPTNO DNAME
---------- --------------------
10 ACCOUNTING
20 RESEARCH
30 SALES
40 OPERATIONS
Seems to be OK.
Using the solution provided by Littefoot, I made some minor tweaks to fit my requirement perfectly:
SQL> create table taba (col1 number,col2 number);
SQL> insert into taba values (1,2);
SQL> select * from taba;
COL1 COL2
---------- ----------
1 2
SQL> create table tabb (col1 number,col2 number, col3 number);
SQL> DECLARE
l_str VARCHAR2 (32767);
BEGIN
FOR cur_r IN (SELECT column_name
FROM user_tab_columns
WHERE table_name = 'TABA'
order by column_id asc)
LOOP
l_str := l_str || ', ' || cur_r.column_name;
END LOOP;
l_str :=
'insert into tabb (' || LTRIM (l_str, ', ') || ') ' ||' select ' || LTRIM (l_str, ', ') || ' from taba';
DBMS_OUTPUT.put_line (l_str);
EXECUTE IMMEDIATE l_str;
END;
/
Output of l_str (SQL INSERT):
insert into tabb (COL1, COL2) select COL1, COL2 from taba
Result:
SQL> select * from tabb;
COL1 COL2 COL3
---------- ---------- ----------
1 2
I have a table where I store records to be used as a column name for my queries where the record is an actual column on another table.
TBL_1
COL_1
==========
SAMPLE_COL
TBL_2
SAMPLE_COL_1 SAMPLE_COL2
============ ===========
ABC DEF
I'm having a problem using the record that I fetched to use as an actual column. I already tried a bunch of things like casting and using case (using case works but it's a bit of a brute force and I'm looking for a more elegant way of doing this).
This is a sample query that I have tried:
SELECT (SELECT column_1 FROM tbl_1)
FROM tbl_2
Expected output
SAMPLE_COL_1
============
ABC
Actual output
(SELECT column_1 FROM tbl_1)
============================
SAMPLE_COL_1
This is what I've tried that worked so far but a brute force technique
SELECT (
CASE
WHEN (SELECT column_1 FROM tbl_2) = 'SAMPLE_COL_1' THEN SAMPLE_COL_1
ELSE SAMPLE_COL_2
END
)
FROM tbl_2
Appreciate the help! Keep safe from COVID-19 everyone :)
It's not that easy as you'd want it to be - you'll have to use dynamic SQL. Here's an example, based on Scott's table(s).
Create a function that accepts table and column names and returns ref cursor.
SQL> create or replace function f_test
2 (par_table_name in varchar2, par_column_name in varchar2)
3 return sys_refcursor
4 is
5 rc sys_refcursor;
6 begin
7 open rc for 'select ' || dbms_assert.simple_sql_name(par_column_name) ||
8 ' from ' || dbms_assert.sql_object_name(par_table_name);
9 return rc;
10 end;
11 /
Function created.
Testing:
SQL> select f_test('dept', 'dname') from dual;
F_TEST('DEPT','DNAME
--------------------
CURSOR STATEMENT : 1
CURSOR STATEMENT : 1
DNAME
--------------
ACCOUNTING
RESEARCH
SALES
OPERATIONS
SQL> select f_test('dual', 'dummy') from dual;
F_TEST('DUAL','DUMMY
--------------------
CURSOR STATEMENT : 1
CURSOR STATEMENT : 1
D
-
X
SQL>
Another example, with column (and table) names stored in a table (something like you posted).
Table that contains those info and the function:
SQL> select * from tbl_1;
TNAM CNAME
---- -----
dept dname
dual dummy
SQL> create or replace function f_test
2 (par_table_name in varchar2)
3 return sys_refcursor
4 is
5 l_str varchar2(1000);
6 rc sys_refcursor;
7 begin
8 select 'select ' || dbms_assert.simple_sql_name(cname) ||
9 ' from ' || dbms_assert.sql_object_name(tname)
10 into l_str
11 from tbl_1
12 where tname = dbms_assert.sql_object_name(par_table_name);
13 open rc for l_str;
14 return rc;
15 end;
16 /
Function created.
Testing:
SQL> select f_test('dept') from dual;
F_TEST('DEPT')
--------------------
CURSOR STATEMENT : 1
CURSOR STATEMENT : 1
DNAME
--------------
ACCOUNTING
RESEARCH
SALES
OPERATIONS
SQL>
I'm trying to build a dynamic function in Oracle using a cursor for all the tables that need to be dropped and re-created again. For example, I have the following example table structure:
CREATE TABLE All_tmp_DATA AS
(SELECT 'T_tmp_test1' As Table_NM, 'TEST1' As Process_name FROM DUAL UNION ALL
SELECT 'T_tmp_test2' As Table_NM, 'TEST1' As Process_name FROM DUAL UNION ALL
SELECT 'T_tmp_test3' As Table_NM, 'TEST1' As Process_name FROM DUAL)
The above tables starting with "T_tmp" represent all the tables in the database which needs to be dropped if their counts are >1 when starting the TEST1 process. I really need a function to pass in the parameter Process_name where I can input "TEST1", and build a loop using a cursor by binding it to the Table_NM from All_tmp_DATA and inserting it into table_name in the following code:
BEGIN
SELECT count(*)
INTO l_cnt
FROM user_tables
WHERE table_name = 'MY_TABLE';
IF l_cnt = 1 THEN
EXECUTE IMMEDIATE 'DROP TABLE my_table';
END IF;
END;
In the beginning, I'd suggest you not to use mixed case when naming Oracle objects.
Test case:
SQL> select * From all_tmp_data;
TABLE_NM PROCE
----------- -----
T_tmp_test1 TEST1
T_tmp_test2 TEST1
T_tmp_test3 TEST1
SQL> create table "T_tmp_test1" as select * From dept;
Table created.
SQL> -- I don't have "T_tmp_test2"
SQL> create table "T_tmp_test3" as select * From emp;
Table created.
SQL>
SQL> select table_name From user_Tables where upper(table_name) like 'T_TMP%';
TABLE_NAME
------------------------------
T_tmp_test3
T_tmp_test1
Procedure which drops tables contained in ALL_TMP_DATA:
as opposed to your code, I concatenated table name with DROP
as you use table names with mixed case, you have to enclose their names into double quotes, always (did I say not do use that?)
As the final select shows, those tables don't exist any more.
SQL> declare
2 l_cnt number;
3 begin
4 for cur_r in (select table_nm from all_tmp_data) loop
5 select count(*) into l_cnt
6 from user_tables
7 where table_name = cur_r.table_nm;
8
9 if l_cnt > 0 then
10 execute immediate ('drop table "' || cur_r.table_nm || '"');
11 end if;
12 end loop;
13 end;
14 /
PL/SQL procedure successfully completed.
SQL> select table_name From user_Tables where upper(table_name) like 'T_TMP%';
no rows selected
SQL>
As of the process column: I have no idea what is it used for so I did exactly that - didn't use it.
You can use the exception handling to handle such scenario directly as follows:
DECLARE
TABLE_DOES_NOT_EXIST EXCEPTION;
PRAGMA EXCEPTION_INIT ( TABLE_DOES_NOT_EXIST, -00942 );
BEGIN
FOR CUR_R IN (
SELECT TABLE_NM
FROM ALL_TMP_DATA
) LOOP
BEGIN
EXECUTE IMMEDIATE 'drop table "' || cur_r.table_nm || '"';
DBMS_OUTPUT.PUT_LINE('"' || cur_r.table_nm || '" table dropped.');
EXCEPTION
WHEN TABLE_DOES_NOT_EXIST THEN
DBMS_OUTPUT.PUT_LINE('"' || cur_r.table_nm || '" table does not exists');
END;
END LOOP;
END;
/
I have to update all the tables having column name like '%DIV%' with a value DD wherever it is MG , I have written the script for it , but I am not getting the idea of how to verify if columns of all the tables are updated to value DD after the activity is performed. I have written this query .
SELECT 'SELECT '||OWNER||'.'||TABLE_NAME||', '||COLUMN_NAME||' FROM '||OWNER||'.'||TABLE_NAME||' WHERE '||COLUMN_NAME||' = ''MG'' ;'
FROM RADHA.CHANGE_TABLE
WHERE VALID_FLAG='Y'
I was planning to make a table structure like
OWNER TABLE_NAME PREV_COUNT
The PREV_COUNT will hold the count of rows having Column Value as MG and after the activity is performed , I will verify with following query if the corresponding rows have been updated to DD .
SELECT 'SELECT '||OWNER||'.'||TABLE_NAME||', '||COLUMN_NAME||' FROM '||OWNER||'.'||TABLE_NAME||' WHERE '||COLUMN_NAME||' = ''DD'' ;' FROM RADHA.CHANGE_TABLE WHERE VALID_FLAG='Y'
And the output of this query would go into table
OWNER TABLE_NAME NEW_COUNT
But I am not able to get how to fetch records from the Select query as it is the string which is written inside the select query but I want the result set such that I can insert the records in my table mentioned above, please guide how to approach further
I don't have your tables, but - based on Scott's sample schema, here's a script which search through all its tables for a column named JOB (line #8) and checks how many of them have value that looks like (hint: like) CLERK in it (line #12).
See how it works, adjust it so that it works for you.
SQL> DECLARE
2 l_str VARCHAR2(500);
3 l_cnt NUMBER := 0;
4 BEGIN
5 FOR cur_r IN (SELECT u.table_name, u.column_name
6 FROM user_tab_columns u, user_tables t
7 WHERE u.table_name = t.table_name
8 AND u.column_name = 'JOB'
9 )
10 LOOP
11 l_str := 'SELECT COUNT(*) FROM ' || cur_r.table_name ||
12 ' WHERE ' || cur_r.column_name || ' like (''%CLERK%'')';
13
14 EXECUTE IMMEDIATE (l_str) INTO l_cnt;
15
16 IF l_cnt > 0 THEN
17 dbms_output.put_line(l_cnt ||' : ' || cur_r.table_name);
18 END IF;
19 END LOOP;
20 END;
21 /
4 : EMP --> there are 4 CLERKs in the EMP table
PL/SQL procedure successfully completed.
SQL>