PLS-00313: "xxxxxx" not declared in this scope

PLS-00313: "string" not declared in this scope

Cause: There is no declaration for the given identifier within the scope of reference. The identifier might be misspelled, its declaration might be faulty, or the declaration might be placed incorrectly in the block structure.
Action: Check the spelling and declaration of the identifier. Also confirm that the declaration is placed correctly in the block structure.


If you do not want some procedures/functions to be publicly available you may not declare them in the package specification.
Declare them only in the package body. The cause of the error is declaration order of the procedures/functions in the package body or lack of forwarding declaration.

For example:

 create or replace package Test_pkg as
  2    procedure Proc1;
  3  end;
  4  /

Package created

create or replace package body Test_pkg as
  2  
  3    procedure proc1 is
  4    begin
  5      proc2;
  6    end;
  7  
  8    procedure Proc2 is
  9    begin
 10      dbms_output.put_line('proc2 is being executed');
 11    end;
 12  
 13  end;
 14  /

Warning: Package body created with compilation errors
Error: PLS-00313: 'PROC2' not declared in this scope

This is happening because we are calling Proc2 which declared later in the package. In this case our choices are:

Declare pro2 before the procedure which calls it

 create or replace package body Test_pkg as
  2  
  3  
  4    procedure Proc2 is
  5    begin
  6      dbms_output.put_line('proc2 is being executed');
  7    end;
  8  
  9    procedure proc1 is
 10    begin
 11      proc2;
 12    end;
 13  
 14  end;
 15  /

Package body created

Use forward declaration.

create or replace package body Test_pkg as
  2  
  3    procedure Proc2;
  4  
  5    procedure proc1 is
  6    begin
  7      proc2;
  8    end;
  9  
 10    procedure Proc2 is
 11    begin
 12      dbms_output.put_line('proc2 is being executed');
 13    end;
 14  
 15  
 16  end;
 17  /

Package body created

SQL> exec test_pkg.Proc1;

proc2 is being executed

PL/SQL procedure successfully completed

How to Fix "ORA-12505, TNS: listener does not currently know of SID given in connect descriptor"

Cause: The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified a SID for an instance (usually a database instance) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.

To properly resolve this error and connect to the appropriate Oracle database, we’ll need to expound a bit on how Oracle behaves and, therefore, what is causing this issue in the first place.

SIDs vs SERVICE_NAMES
It is important to understand the (slight) difference between what Oracle defines as a SID compared to a SERVICE_NAME, as we’ll use this information to create a proper connection string later on.

In Oracle, the system identifier (or SID) is a local identifier of up to eight characters in length that is used to identify a particular database and differentiate it from other databases on the system.

Often the SID is the prefix word or DB_UNIQUE_NAME that precedes the DB_DOMAIN.

SERVICE_NAMES, on the other hand, represent the names by which database instances can be connected to. A SERVICE_NAME will typically follow the format of the SID followed by the database domain, like so: DB_UNIQUE_NAME.DB_DOMAIN

The TNS Listener
When a client is attempting to connect to an Oracle database, rather than connecting to the database directly, there is a broker service that intervenes and handles the connection request for the client.

This broker application is known as the listener and it performs the task of listening for incoming client requests. When a request is received, the listener processes and forwards that request onto the appropriate Oracle database server using a service handler, which just acts as the connection between the listener and the database server.

TNS Names and Configuration
When connecting to an Oracle database, typically your database server will have tnsnames.ora, which is a configuration file that informs the server about NET_SERVICE_NAMES which are valid database connections. By default, this file is located at ORACLE_HOME/network/admin.

For example, a NET_SERVICE_NAME descriptor in tnsnames.ora may be formatted like this:

myDatabaseNetService =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = tcp)(HOST = localhost)(PORT = 1521)(QUEUESIZE = 100))
    (CONNECT_DATA =
      (SERVICE_NAME = bookstore.company.com)
    )
  )

This would define a NET_SERVICE_NAME using the SERVICE_NAME we discussed earlier and connecting to localhost through port 1521.

Connection String
With a bit more knowledge about how Oracle actually connects to databases, we can now look at how connection strings are formatted.


Connect via TNS NAME
When connecting through a NET_SERVICE_NAME as specified in your tnsnames.ora config file, you must use the username, password, and then append the NET_SERVICE_NAME with the @ symbol, like so:

username/password@NET_SERVICE_NAME

Connect via NET_SERVICE_NAME
Thus, for our previous NET_SERVICE_NAME descriptor above, the actual NET_SERVICE_NAME we defined was myTestDatabaseNetService, so our connection string might look something like this:

john/Pass123@myTestDatabaseNetService

Connect via SERVICE_NAME
When connecting through a SERVICE_NAME, you’ll also need to add the host and port, along with the / symbol preceding the SERVICE_NAME itself:

username/password@host:port/SERVICE_NAME

Connect via SID
Finally, if connecting without a configured NET_SERVICE_NAME or even SERVICE_NAME, you can do so directly through the SID by using the : symbol instead of the / symbol as with the SERVICE_NAME connection string:

username/password@host:port:SID

Fix for Oracle12c - ORA-01792: maximum number of columns in a table or view is 1000

SYMPTOMS

It is possible to get an ORA-01792 "MAXIMUM NUMBER OF COLUMNS IN A TABLE OR VIEW IS 1000"  error even when the original query does not select that many columns  in Oracle 12.1.0.2.0 version.

SOLUTION

According to the My Oracle Support, ORA-01792 is caused due to an unpublished bug.
Oracle suggest to alter the query and/or view definitions to avoid the error. However in cases where the SQL cannot be adjusted then the checking can be disabled by hidden parameter "_fix_control"

The workaround is to set "_fix_control"='17376322:OFF'

On Session level
SQL> alter session set "_fix_control"='17376322:OFF';

OR at system level :

SQL> alter system set "_fix_control"='17376322:OFF';

OR

Apply Patch 19509982 if available for your DBVersion and Platform

To download the patch, please follow the steps below:
1) Go To MOS
2) Click on Patches & Updates
3) In the Patch Search Section, enter your patch number <19509982> in the Patch Name or Number field.
4) Click Search
5) Click the patch that meets your DbVersion and platform
6) Read any applicable notes before downloading, then click the download button.