I have 50 databases.
All the table schema in all the databases are the same. If I have a new column to be added to one table, I will have to run 50 times to update in all databases. This is very difficult all the time.
Is there an editor for postgres where there is a way to execute a query in all databases?
Currently, I am using dbeaver. I have to change the connection all the time and execute the query. Please help.
Example: I had to alter a table by adding a column.
ALTER TABLE table-name ADD new-column-name column-definition;
It is very difficult to execute for 50 databases.
For executing this answer, you need to have dblink extension.
DO $$
DECLARE
i text;
BEGIN
FOR i in SELECT datname FROM pg_database
LOOP
EXECUTE 'select * from dblink(''host=localhost
user=postgres
password=postgres
dbname='||i||' port=5432'',''ALTER TABLE table-name ADD new-column-name column-definition'' ) tt(
updated text)'
END LOOP;
END $$
Related
Hey I'm new to Oracle SQL but I'm a frequent user of PostGreSQL and SQL Server. I'm currently trying to run a query that will materialize a table every time I run the query. The actual application is more complicated but here is the general idea:
declare
v_exists number:=0;
BEGIN
select count(1)
into v_exists
from all_tables
where table_name = 'FFF';
if v_exists >0 then
EXECUTE IMMEDIATE 'DROP TABLE FFF';
dbms_output.put_line('Table dropped');
end if;
END;
/
create table fff as
select *
from my_table;
Both blocks of code work if I run them separately but when I run them together it doesn't work. Is there a way to combine these kind of queries in just one script?
Thanks
This is a pattern which is common in SQL Server (and perhaps PostgreSQL too) but which is considered an anti-pattern in Oracle, Oracle provides much better ways of working with data sets than executing DDL on the fly.
One approach is to use PL/SQL collections to cache data in memory. This is suitable when the volumes of data are small, because collections are stored in session memory. Find out more.
Another approach is Global Temporary Tables which are permanent structures with transient data (restricted to scope of transaction or session). Find out more.
The enterprise edition comes with features to pin result sets in memory; this is useful when we want to share the result set across multiple sessions, and the life span of the result set is relatively long (i.e. slowly changing reference data). Find out more.
A further, and perhaps the best, approach is to write efficient queries which obviate the need for caching. DDL is an expensive operation which introduces risk and complexity into applications. The most performative way of doing something is usually to avoid doing it.
Try doing the second as dynamic SQL as well:
declare
v_exists number := 0;
BEGIN
select count(1)
into v_exists
from all_tables
where table_name = 'FFF';
if v_exists >0 then
EXECUTE IMMEDIATE 'DROP TABLE FFF';
dbms_output.put_line('Table dropped');
end if;
EXECUTE IMMEDIATE 'create table fff as select * from my_table';
END;
/
An alternative is a script in SQLPLUS;
WHENEVER SQLERROR CONTINUE
DROP TABLE fff
/
WHENEVER SQLERROR EXIT FAILURE
CREATE TABLE fff
AS SELECT * FROM my_table
/
This will try to drop the table but if it can't will carry on and then try to create the table. If that fails for some reason then the script will fail.
All i want is to select all rows from a table and once it is selected and displayed, the data residing in table must get completely deleted. The main concern is that this must be done using sql only and not plsql. Is there a way we can do this inside a package and call that package in a select statement? Please enlighten me here.
Dummy Table is as follows:
ID NAME SALARY DEPT
==================================
1 Sam 50000 HR
2 Max 45000 SALES
3 Lex 51000 HR
4 Nate 66000 DEV
Any help would be greatly appreciated.
select * from Table_Name;
Delete from Table_Name
To select the data from a SQL query try using a pipelined function.
The function can define a cursor for the data you want (or all the data in the table), loop through the cursor piping each row as it goes.
When the cursor loop ends, i.e. all data has been consumed by your query, the function can perform a TRUNCATE table.
To select from the function use the following syntax;
SELECT *
FROM TABLE(my_function)
See the following Oracle documentation for information pipelined functions - https://docs.oracle.com/cd/B28359_01/appdev.111/b28425/pipe_paral_tbl.htm
This cannot be done inside a package, because " this must be done using sql only and not plsql". A package is PL/SQL.
However it is very simple. You want two things: select the table data and delete it. Two things, two commands.
select * from mytable;
truncate mytable;
(You could replace truncate mytable; with delete from mytable;, but this is slower and needs to be followed by commit; to confirm the deletion and end the transaction.)
Without pl/sql it's not possible.
Using pl/sql you can create a function which will populate a row, and then delete
Here is example :
drop table tempdate;
create table tempdate as
select '1' id from dual
UNION
select '2' id from dual
CREATE TYPE t_tf_row AS OBJECT (
id NUMBER
);
CREATE TYPE t_tf_tab IS TABLE OF t_tf_row;
CREATE OR REPLACE FUNCTION get_tab_tf RETURN t_tf_tab PIPELINED AS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
FOR rec in (select * from tempdate) LOOP
PIPE ROW(t_tf_row(rec.id));
END LOOP;
delete from tempdate ; commit;
END;
select * from table(get_tab_tf) -- it will populate and then delete
select * from tempdate --you can check here result of deleting
you can use below query
select * from Table_demo delete from Table_demo
The feature you seek is SERIALIZABLE ISOLATION LEVEL. This feature enables repeatable reads, which in particular guarantee that both SELECTand DELETEwill read and process the same identical data.
Example
Alter session set isolation_level=serializable;
select * from tempdate;
--- now insert from other session a new record
delete from tempdate ;
commit;
-- re-query the table old records are deleted, new recor preserved.
I am trying to create a script to update passwords for a large number of users listed in a given table.
alter user FOO identified by FOOWORD;
I can call the usernames via the following statement:
select owner from usertable_verson where rownum = 1
Is there a way to combine these two statements, so that the alter user command works for each result of the select command?
The eventual goal is to create a loop for each username in the selected column, and apply the password change to each.
you can do this via dynamic SQL
smth like this:
begin
for rc in (select owner from usertable_verson) loop
execute immediate 'alter user '||rc.owner||' identified by FOOWORD';
end loop;
end;
I have more than 40 tables in RATOR_MONITORING schema for which the table name is starting from 'TEMP_'. I want to delete data from all such tables at once in a single query instead of using delete statement for each and every table. I dont even want to generate statements. I can create anonymous block if required but dont know how to do that. I tried below query but its not working.
Delete from RATOR_MONITORING_CONFIGURATION.'%TEMP_';
If you want to delete all the rows, then better use TRUNCATE, it will reset the high watermark. But remember, truncate is a DDL statement, and thus there will be an implicit commit; With DELETE you can commit manually after validation.
Although, I would not do that in a production environment. If it is something you are doing in test environment to build test data, then you could (ab)use EXECUTE IMMEDIATE.
For example, execute the following anonymous block as RATOR_MONITORING user:
DECLARE
v_sql VARCHAR2(100);
BEGIN
FOR i IN
(SELECT table_name FROM user_tables where table_name like 'TEMP%'
)
LOOP
v_sql := 'TRUNCATE TABLE '||i.table_name;
EXECUTE immediate v_sql;
END LOOP;
END;
/
By the way, using a good text editor, it won't take more than a minute to build DELETE/TRUNCATE statements and do it in pure SQL.
I want to call create table/ alter table command from a procedure. Is it possible?
My requirement is to change the datatype of a column in all tables. So, I am just getting the column name from user_tab_cols. Now I want to create a temp table which requires create statement .. but i am unable to use that within a proc.
Can anyone please help me out?
I presume from the reference to USER_TAB_COLUMNS that this is Oracle. ALTER and CREATE statements are DDL, which we cannot execute directly in PL/SQL. However, there are a couple of ways around this restriction: EXECUTE IMMEDIATE and DBMS_UTILITY.EXEC_DDL(). I will use EXECUTE IMMEDIATE in the following example.
begin
for lrec in ( select table_name from user_tab_columns
where column_name = 'UNIVERSAL_COLUMN_NAME')
loop
execute immediate 'alter table '||lrec.table_name||
' modify UNIVERSAL_COLUMN_NAME varchar2(255)';
end loop;
end;
Note that the usual restrictions apply: the new datatype has to be compatible with the existing datatype (unless the column is empty), and things are trickier with some specilaized datatypes like CLOBs.
edit
I haven't addressed the CREATE TABLE statement. The principle is the same, it is just longer to type out. Besides, I am not entirely clear how it applies to your prior requirement to change the datatype of those columns.
you can generate the query as string and execute it with 'exec' keyword.