Tuesday, September 5, 2023

ssh-keygen commands in linux and windows

 locations:-

windows :-

C:\Users\<username>\.ssh

C:\Users\<username>\.ssh\authorized_keys

C:\Users\<username>\.ssh\id_rsa                  👈private key 

C:\Users\<username>\.ssh\id_rsa.pub            👈public key


Linux :-

/home/<username>/.ssh 

/home/<username>/.ssh/authorized_keys        👈authorized key  

/home/<username>/.ssh/id_rsa                        👈private key 

/home/<username>/.ssh/id_rsa.pub                 👈public key 


permissions:-

chmod 700 ~/.ssh  or   chmod 777  /home/<username>/.ssh 

chmod 600 ~/.ssh/authorized_keys  or   chmod  600  /home/<username>/.ssh/authorized_keys

chmod 600 ~/.ssh/id_rsa            or chmod 600   /home/<username>/.ssh/id_rsa

chmod 644 ~/.ssh/id_rsa.pub    or chmdo 644    /home/<username>/.ssh/id_rsa.pub


To generate ssh key on windows and linux 

ssh-keygen -t rsa -b 4096 -C  "user@gmail.com"  

or

ssh-keygen -t rsa 




###########################################################################

share your id_rsa.pub key to target server ~/.ssh directory and activate id_rsa private key on source server(your own server/windows)

###########################################################################

Monday, September 4, 2023

Maths on Linux Terminal

 for i in {1..10}; do echo | awk -v var=$i '{print var}' ; done

[oracle@stby ~]$  for i in {1..10}; do echo | awk -v var=$i '{print var}' ; done;
1
2
3
4
5
6
7
8
9
10


----------------------------------------------------------------------
$ a=55
$ b=87
$ echo $((a+b))

[oracle@stby ~]$ a=55
[oracle@stby ~]$ b=45
[oracle@stby ~]$
[oracle@stby ~]$ echo | awk -v var0=$a -v var1=$b '{print "division is: ", var1/var0}'
division is:  0.818182


to have division :-
============
[oracle@stby ~]$ printf "%.01f\n" $(echo "scale=1; 4/9" | bc)
0.4
[oracle@stby ~]$ printf "%.02f\n" $(echo "scale=1; 4/9" | bc)
0.40
[oracle@stby ~]$ printf "%.03f\n" $(echo "scale=1; 4/9" | bc)
0.400
[oracle@stby ~]$ printf "%.03f\n" $(echo "scale=3; 4/9" | bc)
0.444
[oracle@stby ~]$ printf "%.06f\n" $(echo "scale=6; 4/9" | bc)
0.444444
[oracle@stby ~]$ # %.0nf 👉"n"--- number of digits after decimal
[oracle@stby ~]$ # scale=6 👉 numbers of decimals digits can be calculated

1. unziping 
unzip -o /path/to/source/*.zip -d /path/to/destination/
-o :- source
-d :- destination

2. cat file_name
3. strings binary_file
4. tar -cvzf backup.tar.gz --remove-files dir/
-cvzf :- create zip file
-xvzf :- extract zip file
--remove-files :- once the file archived it will then get deleted.

5. export day=Monday
unset day

6. date -d 'tomorrow'
date -d 'next week'
date -d 'next sun'
date -d 'next year'
date -d 'next month'
date -d 'next day'
date -d +'%r' for 12 hour timing
date -d +'%R' for 24 hour timing
date + %b   ---> Sep
date + %B   ---> September
date -d '+- days/months/years' +'%Y_%m_%d %H_%M_%s'   ---> like 2023_09_04 09_05_45

7. to see shell 
echo $SHELL

8. to do maths
echo $(( 5+5 ))
printf "%.0f\n" $(echo "scale=1; 2/5" | bc)   ---> 
%.0f ---> 1
%.01f --> 1.0
%.02f --> 1.00
%.03f --> 1.000
i.e %.0nf ---> n means number of digits after decimal.

Tuesday, August 29, 2023

SCP COMMAND SPECIAL USAGE

scp source_user@source_hostname:/path/to/source/directory/file_{1..50}_*  target_user@target_hostname:/path/to/target/directory/



go to target server location then use below command:-

scp source_user@source_hostname:/path/to/source/directory/file_{1..50}_*  .


Oracle Directories



Wednesday, August 23, 2023

synonyms and views

public synonym:- create public synonym name for scott.students;

private synonym:- create synonym name for scott.students;

public view :- create or replace view name as (select * from scott.students);


Monday, August 21, 2023

tablespace datafiles sizes in KB MB GB TB PB EB ZB YB

select 
file_id,
tablespace_name,
file_name,
bytes,
case 
when bytes between 0 and 1023 then bytes || ' bytes'
when bytes < power(1024,2) then round(bytes / 1024,4) || ' KB'
when bytes < power(1024,3) then round(bytes / power(1024,2),4) || ' MB'
when bytes < power(1024,4) then round(bytes / power(1024,3),4) || ' GB'
when bytes < power(1024,5) then round(bytes / power(1024,4),4) || ' TB'
when bytes < power(1024,6) then round(bytes / power(1024,5),4) || ' PB'
when bytes < power(1024,7) then round(bytes / power(1024,6),4) || ' EB'
when bytes < power(1024,8) then round(bytes / power(1024,7),4) || ' ZB'
when bytes < power(1024,9) then round(bytes / power(1024,8),4) || ' YB'
else 'INVALID VALUE FOR BYTES'
end as bytes_sizes
from dba_data_files;

------------------------------ to get full detail of imported objects on target db ----------------------
select 
(select host_name from v$instance) "Host", 
(select instance_name from v$instance) "Instance",
owner,
segment_name,
(select 
to_char(cast(created as timestamp with local time zone), 'DD-MONTH-YYYY hh24:mi:ss TZD yyyy') "created" from dba_objects where object_name='&object_name' and owner='&schema_name') "created",
(select to_char( cast(sysdate as timestamp with local time zone), 'DD-MONTH-YYYY hh24:mi:ss TZD yyyy') from dual) "sysdate",
case 
when bytes between 0 and 1023 then bytes || 'bytes'
when bytes < power(1024,2) then round(bytes / power(1024,1),4) || 'KB'
when bytes < power(1024,3) then round(bytes / power(1024,2),4) || 'MB'
when bytes < power(1024,4) then round(bytes / power(1024,3),4) || 'GB'
when bytes < power(1024,5) then round(bytes / power(1024,4),4) || 'TB'
when bytes < power(1024,6) then round(bytes / power(1024,5),4) || 'PB'
when bytes < power(1024,7) then round(bytes / power(1024,6),4) || 'EB'
when bytes < power(1024,8) then round(bytes / power(1024,7),4) || 'ZB'
when bytes < power(1024,9) then round(bytes / power(1024,8),4) || 'YB'
else 'INVALID VALUE FOR BYTES'
end as bytes_sizes
from dba_segments
where segment_name='&table_name' and owner='schema_name';



select tablespace_name,warning_value,critical_value from dba_tablespace_thresholds where tablespace_name=upper('&tablespace_name');

important views in oracle 

dba_tablespace_thresholds
dba_thresholds
dba_triggers
dba_ts_quotas
all_apply_quotas
all_apply_error
all_certificates
all_goldengate_privileges
all_goldengate_rule
all_goldengate_inbound
all_lobs
all_method_params
all_external_locations
all_credentials

Friday, August 18, 2023

Apache httpd tomcat Server setup on linux

 How To setup apache tomcat httpd server on linux:-

1. dnf install httpd; dnf install apache*
2. systemctl enable --now httpd.service
3.sestatus --> /etc/selinux/config ---> set selinux=permissive
4. if possible :- 
systemctl stop firewalld.service
systemctl disable firewalld.service
or 
firewall-cmd --add-service=http --permanent
firewall-cmd --reload
go  to chrome/edge:-
http://pm
it will show you the html file from :-
/etc/httpd/conf/httpd.conf
/var/www/html/index.html (you need to create and add your html content)
logs:-
var/log/httpd
when you change/modify "/var/www/html/index.html" do : systemctl restart httpd

*********** my own  setup ****************
[root@pm Videos]# ls
getorareport.sh  index.html
[root@pm Videos]#
[root@pm Videos]#
[root@pm Videos]# pwd
/home/oracle/Videos
[root@pm Videos]# cat getorareport.sh
#!/bin/sh

export ORACLE_HOME=/u02/app/oracle/product/21c/dbhome_1
export ORACLE_SID=chennai
export PATH=$ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib

sqlplus /nolog <<!!
conn sys/Kayyum#424304 as sysdba;
set markup HTML on;
set lines 400;
col host_name for a20;
spool index.html
select host_name,instance_name from gv\$instance;
spool off;
set markup HTML off;
exit;
!!


# export to /var/www/html/index.html

cat /home/oracle/Videos/index.html > /var/www/html/index.html
[root@pm Videos]#
[root@pm Videos]# whoami
root
[root@pm Videos]# crontab -l
* * * * * /home/oracle/Videos/getorareport.sh > /dev/null 2>&1
[root@pm html]# ls
index.html
[root@pm html]# pwd
/var/www/html
[root@pm html]# ls -lrt
total 4
-rw-r--r--. 1 root root 310 Aug 18 14:33 index.html
[root@pm html]#



*****************************************************************
[root@pm conf]# cat httpd.conf
#
# This is the main Apache HTTP server configuration file.  It contains the
# configuration directives that give the server its instructions.
# See <URL:http://httpd.apache.org/docs/2.4/> for detailed information.
# In particular, see
# <URL:http://httpd.apache.org/docs/2.4/mod/directives.html>
# for a discussion of each configuration directive.
#
# See the httpd.conf(5) man page for more information on this configuration,
# and httpd.service(8) on using and configuring the httpd service.
#
# Do NOT simply read the instructions in here without understanding
# what they do.  They're here only as hints or reminders.  If you are unsure
# consult the online docs. You have been warned.
#
# Configuration and logfile names: If the filenames you specify for many
# of the server's control files begin with "/" (or "drive:/" for Win32), the
# server will use that explicit path.  If the filenames do *not* begin
# with "/", the value of ServerRoot is prepended -- so 'log/access_log'
# with ServerRoot set to '/www' will be interpreted by the
# server as '/www/log/access_log', where as '/log/access_log' will be
# interpreted as '/log/access_log'.

#
# ServerRoot: The top of the directory tree under which the server's
# configuration, error, and log files are kept.
#
# Do not add a slash at the end of the directory path.  If you point
# ServerRoot at a non-local disk, be sure to specify a local disk on the
# Mutex directive, if file-based mutexes are used.  If you wish to share the
# same ServerRoot for multiple httpd daemons, you will need to change at
# least PidFile.
#
ServerRoot "/etc/httpd"

#
# Listen: Allows you to bind Apache to specific IP addresses and/or
# ports, instead of the default. See also the <VirtualHost>
# directive.
#
# Change this to Listen on specific IP addresses as shown below to
# prevent Apache from glomming onto all bound IP addresses.
#
#Listen 12.34.56.78:80
Listen 80

#
# Dynamic Shared Object (DSO) Support
#
# To be able to use the functionality of a module which was built as a DSO you
# have to place corresponding `LoadModule' lines at this location so the
# directives contained in it are actually available _before_ they are used.
# Statically compiled modules (those listed by `httpd -l') do not need
# to be loaded here.
#
# Example:
# LoadModule foo_module modules/mod_foo.so
#
Include conf.modules.d/*.conf

#
# If you wish httpd to run as a different user or group, you must run
# httpd as root initially and it will switch.
#
# User/Group: The name (or #number) of the user/group to run httpd as.
# It is usually good practice to create a dedicated user and group for
# running httpd, as with most system services.
#
User apache
Group apache

# 'Main' server configuration
#
# The directives in this section set up the values used by the 'main'
# server, which responds to any requests that aren't handled by a
# <VirtualHost> definition.  These values also provide defaults for
# any <VirtualHost> containers you may define later in the file.
#
# All of these directives may appear inside <VirtualHost> containers,
# in which case these default settings will be overridden for the
# virtual host being defined.
#

#
# ServerAdmin: Your address, where problems with the server should be
# e-mailed.  This address appears on some server-generated pages, such
# as error documents.  e.g. admin@your-domain.com
#
ServerAdmin root@localhost

#
# ServerName gives the name and port that the server uses to identify itself.
# This can often be determined automatically, but we recommend you specify
# it explicitly to prevent problems during startup.
#
# If your host doesn't have a registered DNS name, enter its IP address here.
#
#ServerName www.example.com:80

#
# Deny access to the entirety of your server's filesystem. You must
# explicitly permit access to web content directories in other
# <Directory> blocks below.
#
<Directory />
    AllowOverride none
    Require all denied
</Directory>

#
# Note that from this point forward you must specifically allow
# particular features to be enabled - so if something's not working as
# you might expect, make sure that you have specifically enabled it
# below.
#

#
# DocumentRoot: The directory out of which you will serve your
# documents. By default, all requests are taken from this directory, but
# symbolic links and aliases may be used to point to other locations.
#
DocumentRoot "/var/www/html"

#
# Relax access to content within /var/www.
#
<Directory "/var/www">
    AllowOverride None
    # Allow open access:
    Require all granted
</Directory>

# Further relax access to the default document root:
<Directory "/var/www/html">
    #
    # Possible values for the Options directive are "None", "All",
    # or any combination of:
    #   Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
    #
    # Note that "MultiViews" must be named *explicitly* --- "Options All"
    # doesn't give it to you.
    #
    # The Options directive is both complicated and important.  Please see
    # http://httpd.apache.org/docs/2.4/mod/core.html#options
    # for more information.
    #
    Options Indexes FollowSymLinks

    #
    # AllowOverride controls what directives may be placed in .htaccess files.
    # It can be "All", "None", or any combination of the keywords:
    #   Options FileInfo AuthConfig Limit
    #
    AllowOverride None

    #
    # Controls who can get stuff from this server.
    #
    Require all granted
</Directory>

#
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
<IfModule dir_module>
    DirectoryIndex index.html
</IfModule>

#
# The following lines prevent .htaccess and .htpasswd files from being
# viewed by Web clients.
#
<Files ".ht*">
    Require all denied
</Files>

#
# ErrorLog: The location of the error log file.
# If you do not specify an ErrorLog directive within a <VirtualHost>
# container, error messages relating to that virtual host will be
# logged here.  If you *do* define an error logfile for a <VirtualHost>
# container, that host's errors will be logged there and not here.
#
ErrorLog "logs/error_log"

#
# LogLevel: Control the number of messages logged to the error_log.
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
#
LogLevel warn

<IfModule log_config_module>
    #
    # The following directives define some format nicknames for use with
    # a CustomLog directive (see below).
    #
    LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
    LogFormat "%h %l %u %t \"%r\" %>s %b" common

    <IfModule logio_module>
      # You need to enable mod_logio.c to use %I and %O
      LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio
    </IfModule>

    #
    # The location and format of the access logfile (Common Logfile Format).
    # If you do not define any access logfiles within a <VirtualHost>
    # container, they will be logged here.  Contrariwise, if you *do*
    # define per-<VirtualHost> access logfiles, transactions will be
    # logged therein and *not* in this file.
    #
    #CustomLog "logs/access_log" common

    #
    # If you prefer a logfile with access, agent, and referer information
    # (Combined Logfile Format) you can use the following directive.
    #
    CustomLog "logs/access_log" combined
</IfModule>

<IfModule alias_module>
    #
    # Redirect: Allows you to tell clients about documents that used to
    # exist in your server's namespace, but do not anymore. The client
    # will make a new request for the document at its new location.
    # Example:
    # Redirect permanent /foo http://www.example.com/bar

    #
    # Alias: Maps web paths into filesystem paths and is used to
    # access content that does not live under the DocumentRoot.
    # Example:
    # Alias /webpath /full/filesystem/path
    #
    # If you include a trailing / on /webpath then the server will
    # require it to be present in the URL.  You will also likely
    # need to provide a <Directory> section to allow access to
    # the filesystem path.

    #
    # ScriptAlias: This controls which directories contain server scripts.
    # ScriptAliases are essentially the same as Aliases, except that
    # documents in the target directory are treated as applications and
    # run by the server when requested rather than as documents sent to the
    # client.  The same rules about trailing "/" apply to ScriptAlias
    # directives as to Alias.
    #
    ScriptAlias /cgi-bin/ "/var/www/cgi-bin/"

</IfModule>

#
# "/var/www/cgi-bin" should be changed to whatever your ScriptAliased
# CGI directory exists, if you have that configured.
#
<Directory "/var/www/cgi-bin">
    AllowOverride None
    Options None
    Require all granted
</Directory>

<IfModule mime_module>
    #
    # TypesConfig points to the file containing the list of mappings from
    # filename extension to MIME-type.
    #
    TypesConfig /etc/mime.types

    #
    # AddType allows you to add to or override the MIME configuration
    # file specified in TypesConfig for specific file types.
    #
    #AddType application/x-gzip .tgz
    #
    # AddEncoding allows you to have certain browsers uncompress
    # information on the fly. Note: Not all browsers support this.
    #
    #AddEncoding x-compress .Z
    #AddEncoding x-gzip .gz .tgz
    #
    # If the AddEncoding directives above are commented-out, then you
    # probably should define those extensions to indicate media types:
    #
    AddType application/x-compress .Z
    AddType application/x-gzip .gz .tgz

    #
    # AddHandler allows you to map certain file extensions to "handlers":
    # actions unrelated to filetype. These can be either built into the server
    # or added with the Action directive (see below)
    #
    # To use CGI scripts outside of ScriptAliased directories:
    # (You will also need to add "ExecCGI" to the "Options" directive.)
    #
    #AddHandler cgi-script .cgi

    # For type maps (negotiated resources):
    #AddHandler type-map var

    #
    # Filters allow you to process content before it is sent to the client.
    #
    # To parse .shtml files for server-side includes (SSI):
    # (You will also need to add "Includes" to the "Options" directive.)
    #
    AddType text/html .shtml
    AddOutputFilter INCLUDES .shtml
</IfModule>

#
# Specify a default charset for all content served; this enables
# interpretation of all content as UTF-8 by default.  To use the
# default browser choice (ISO-8859-1), or to allow the META tags
# in HTML content to override this choice, comment out this
# directive:
#
AddDefaultCharset UTF-8

<IfModule mime_magic_module>
    #
    # The mod_mime_magic module allows the server to use various hints from the
    # contents of the file itself to determine its type.  The MIMEMagicFile
    # directive tells the module where the hint definitions are located.
    #
    MIMEMagicFile conf/magic
</IfModule>

#
# Customizable error responses come in three flavors:
# 1) plain text 2) local redirects 3) external redirects
#
# Some examples:
#ErrorDocument 500 "The server made a boo boo."
#ErrorDocument 404 /missing.html
#ErrorDocument 404 "/cgi-bin/missing_handler.pl"
#ErrorDocument 402 http://www.example.com/subscription_info.html
#

#
# EnableMMAP and EnableSendfile: On systems that support it,
# memory-mapping or the sendfile syscall may be used to deliver
# files.  This usually improves server performance, but must
# be turned off when serving from networked-mounted
# filesystems or if support for these functions is otherwise
# broken on your system.
# Defaults if commented: EnableMMAP On, EnableSendfile Off
#
#EnableMMAP off
EnableSendfile on

# Supplemental configuration
#
# Load config files in the "/etc/httpd/conf.d" directory, if any.
IncludeOptional conf.d/*.conf
[root@pm conf]#


Thursday, August 17, 2023

oracle errors and how to resolve them

 fix for ORA-03113 end-of-file on communication channel:-

1. SQLPLUS / AS SYSDBA

2. startup mount;

SQL> alter database clear unarchived logfile group 1;

Database altered.

SQL> alter database clear unarchived logfile group 2;

Database altered.
SQL> alter database clear unarchived logfile group 3;

SQL> shut immediate;
SQL> startup ;

Wednesday, August 16, 2023

File Automation Script

 #!/bin/sh
 
echo "Enter file name: "
read file
if test -e ${file}
then
select user in empty directory readable writable
do
        case ${user} in
                "empty")
                        if test -s ${file}
                        then
                                echo "${file}-->is not empty"
                        else
                                echo "${file}-->is empty"
                        fi
                        ;;
                "directory")
                        if test -d ${file}
                        then
                                echo "${file}-->is a directory"
                        else
                                echo "${file}-->is not a directory"
                        fi
                        ;;
                "readable")
                        if test -r ${file}
                        then
                                echo "${file}-->is readable"
                        else
                                echo "${file}-->is not readable"
                        fi
                        ;;
                "writable")
if test -w ${file}
                        then
                                echo "${file}-->is writable"
                        else
                                echo "${file}-->is not writable"
                        fi
                        ;;
                "executable")
                        if test -x ${file}
                        then
                                echo "${file}-->is executable"
                        else
                                echo "${file}-->is not executable"
                        fi
                        ;;
        esac
done
else 
    echo "${file}-->not found"
fi


*********************************************************************
stat file.txt
  File: file.txt
  Size: 1               Blocks: 8          IO Block: 4096   regular file
Device: ch/12d  Inode: 229149      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2023-08-17 11:26:26.803000000 +0530
Modify: 2023-08-17 11:26:26.803000000 +0530
Change: 2023-08-17 11:26:26.803000000 +0530
 Birth: -

database link in oracle database

 Make sure we have database entries of target db in tnsnames.ora

------------------------------------------------------------------

CREATE DATABASE LINK remote_db_link
CONNECT TO username IDENTIFIED BY password
USING 'remote_database_tns';

CREATE PUBLIC DATABASE LINK link_name
CONNECT TO username IDENTIFIED BY password
USING 'tns_string';

[oracle@pm admin]$ cat tnsnames.ora
chennai  =    # ----> this is "tns_string"
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = pm.shaikh.com)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SID = chennai)
    )
  )


SELECT * FROM remote_table@remote_db_link;


drop public database link db_link_name;
drop database link db_link_name;

select * from all_db_links;
select * from dba_db_links;
select * from user_db_links;

set lines 400;
col owner for a10;
col db_link for a30;
col username for a20;
col host for a20;
select owner,db_link,username,host from all_db_links;

Saturday, August 12, 2023

How to find same columns in multiple tables/views

 How to find same columns in multiple tables/views

********************************************************

col table_name for a20;
col column_name for a20;
select 
a.table_name,a.column_name,
b.table_name,b.column_name,
c.table_name,c.column_name
from 
(select * from all_tab_columns where table_name='DBA_DATA_FILES') a
inner join
(select * from all_tab_columns where table_name='DBA_FREE_SPACE') b
on a.column_name=b.column_name
inner join 
(select * from all_tab_columns where table_name='DBA_EXTENTS') c
on b.column_name=c.column_name;

*************************************************************


TABLE_NAME           COLUMN_NAME          TABLE_NAME           COLUMN_NAME          TABLE_NAME           COLUMN_NAME         

-------------------- -------------------- -------------------- -------------------- -------------------- --------------------

DBA_DATA_FILES       FILE_ID              DBA_FREE_SPACE       FILE_ID              DBA_EXTENTS          FILE_ID             

DBA_DATA_FILES       TABLESPACE_NAME      DBA_FREE_SPACE       TABLESPACE_NAME      DBA_EXTENTS          TABLESPACE_NAME     

DBA_DATA_FILES       BYTES                DBA_FREE_SPACE       BYTES                DBA_EXTENTS          BYTES               

DBA_DATA_FILES       BLOCKS               DBA_FREE_SPACE       BLOCKS               DBA_EXTENTS          BLOCKS              

DBA_DATA_FILES       RELATIVE_FNO         DBA_FREE_SPACE       RELATIVE_FNO         DBA_EXTENTS          RELATIVE_FNO        


***********************************************************************************

Automation Script:-
-------------------------------
col table_name for a20;
col column_name for a20;
select 
a.table_name,a.column_name,
b.table_name,b.column_name,
c.table_name,c.column_name
from 
(select * from all_tab_columns where table_name = upper('&table_a')) a
inner join
(select * from all_tab_columns where table_name = upper('&table_b')) b
on a.column_name=b.column_name
inner join 
(select * from all_tab_columns where table_name = upper('&table_c')) c
on b.column_name=c.column_name;

******************************************************


Enable OpenSSH on Windows 11

Step 1: Install OpenSSH Server You can do this via PowerShell (run as Administrator ): Check if it's already available: Get-WindowsCapab...