ORA-00918 also referred to as an ORA 918 is a common issue/error that occurs during the development of queries through joins of multiple tables and other issues listed below.  Most of the time an Ora-00918 occurs due to the fact that a column with the same name exists in both tables. Another not so well documented reason for this issue to occur is the initial definition of views using a "select *" followed by addition of columns to the underlying table.

UTL_FILE package built into the oracle database allows PL/SQL programs to read and write to an operating system file. The UTL FILE package has been available since PL/SQL 2.3 and has become the easiest interface to use in generating flat files from the database to get around the limitations of DBMS_OUTPUT package.  To read or write to a file using UTL_FILE, you call FOPEN, which returns a file handle for use in subsequent calls.  For example procedures like PUT_LINE can be used to write a line to the open file and GET_LINE can be used to read a line from the file file.

Oracle installs many PL/SQL packages during the installation of the Oracle database. These packages are used to extend the database functionality and also to provide the necessary access to SQL features. The DBMS packages also referred to as built-in packages are created during the execution of catproc.sql. Each package has its own creation script that can be found in the $ORACLE_HOME/rdbms/admin directory. You can use the supplied packages when creating your applications or for ideas in creating your own stored procedures. Some examples of such packages include standard, DBMS_SQL, DBMS_STATS, DBMS_OUTPUT, DBMS_LOB, DBMS_LDAP etc. This article will give you an overview of each of these packages and what they are used for in the oracle database    

Oracle DBMS_JOB package is a built-in package that is used as an API/Interface to manage the Oracle job queue.  The oracle job queue is the mechanism that is used to schedule the execution of various PL/SQL Blocks or Procedures at predefined intervals of time.  The DBMS_JOB package contains various sub programs that can be used to manage the submission, execution and management of the jobs in the oracle job queue.  http://oracle.mydatabasesupport.com/plsql/dbms-job-package.html

ORA-01008: not all variables bound

Cause: A SQL statement containing substitution variables was executed without all variables bound. All substitution variables must have a substituted value before the SQL statement is executed.

Action: In OCI, use an OBIND or OBINDN call to substitute the required values.