How to resolve ORA-00904: invalid identifier

ORA-00904: invalid identifier is one of the common error seen. Reference: Oracle documentation One of the most common cause of this error Invalid identifier means the column name entered is either missing or invalid. It also Some time comes  when you used reserved word in Oracle database. Check List to resolve the ORA error  It comes when you put extra comma in the create table … Continue reading How to resolve ORA-00904: invalid identifier »

copy directory linux command examples

While working on project/development in Linux operation system , we often need to  backup the current working folder i.e copy directory .  We will be seeing here various ways to copy directory linux. Linux Operating system provides cp command to copy the files/directory from one place to another  and mv command to move the file/directory.I would explaining each command in details here with many examples … Continue reading copy directory linux command examples »

ORA-00001 unique constraint violated

ORA-0001 unique constraint violated is one of the common message we often get while loading data. This error occurs when You tried to execute an INSERT or UPDATE statement that has created a duplicate value in a field restricted by a unique index. We can perform following action items for this error  You can look at the error and find the constraint information with the below sql … Continue reading ORA-00001 unique constraint violated »

How to work with date in Oracle sql

This post I am trying to explain many things  about oracle date datatype like oracle sql date functions,oracle sql date format, oracle sql date comparison, oracle date difference in  years,oracle date difference in  days, oracle date difference in  months Oracle has provided date and timestamp type for storing the date and time information in the database. Date Type DATE is the datatype that we are all familiar with … Continue reading How to work with date in Oracle sql »

How to resolve the ORA-00936 missing expression

ORA-00936 missing expression is one of the common error everybody working in Oracle sql must have faced some time. This generally happens when you omit important thing in the sql statement i.e you left out an important chunk of what you were trying to run Reference : Oracle documentation This Oracle error is mainly related to the SQL SELECT statements. One obvious reason is select column … Continue reading How to resolve the ORA-00936 missing expression »

How to resolve ORA-00900

ORA-00900 is one of the common error Here what oracle documentation says about it Reference: Oracle documentation Checklist to solve the ORA-00900 error This error commonly occurs when you are trying to create an Oracle procedure and the Procedural Option is not installed.To determine if the Procedural Option has been installed, open an Oracle session using SQL*Plus. If the PL/SQL banner does not display, then … Continue reading How to resolve ORA-00900 »

How to resolve the ORA-01017: invalid username/password; logon denied

ORA-01017  is one of the common error seen in PLSQL programs. Here is what documentation says about this error Here are the checklist to run to resolve the error The main issue with an ORA-01017 error is an invalid user ID and passwords combination.  You have to make sure ,you are entering the right password Incase the target system is 11g, the password can be … Continue reading How to resolve the ORA-01017: invalid username/password; logon denied »

How to resolve ORA-06512 at line num

ORA-06512  is one of the common error seen in PLSQL programs. Here is what documentation says about this error Reference :Oracle documentation Explanation of the error: Error Ora-06512 means the backtrace message as the stack is being unwound by unhandled exceptions in your PLSQL code. This is a catch-all error for PLSQL exceptions and is commonly seen. Ora-06512 does not indicate the actual error, but … Continue reading How to resolve ORA-06512 at line num »

How to use tar command in Unix

In continuation of our series of Unix tutorial ,i am here presenting the Unix Tutorial:  tar command example tar – create tape archives and add or extract files.A more common use for tar is to simply combine a few files into a single file, for easy storage and distribution. The tar command archives and extracts files to and from a single file called a tarfile. -I … Continue reading How to use tar command in Unix »

Must read unix shell scripting interview questions

Unix is used everywhere and knowledge of the operating system is must for any interview. Here are the must read  unix shell scripting interview questions 1) What is Shell Script? Answer A shell script is a collection of command which are executed in a order given. There are conditional statement and looping also available like if ,while which helps in finding if a particular value is … Continue reading Must read unix shell scripting interview questions »

Oracle PLSQL Tables

PLSQL tables are composite datatypes. These behave in the same way as arrays except that have no upper bounds, allowing them to constantly extend. They are also called index by table PLSQL Table contains two elements 1) A primary key of BINARY_INTEGER datatypes that index the table, which do not need to be consecutive. The collection is extended by assigning values to an element using … Continue reading Oracle PLSQL Tables »

awk command in unix with examples

Awk is a powerful command. In this post,i will try to put awk command in unix with examples What is awk command in Unix? a)awk is a Pattern Scanning and Processing Language. b)awk is a programming language whose basic operation is to search a set of files for patterns, and to perform specified actions upon lines or fields of lines which contain instances of those … Continue reading awk command in unix with examples »