Skip to main content

SQL Query to find number of columns of a table


I have been receiving lots of mails on how to find number of columns of a table without using DESCRIBE command or using a statement.

This is very simple, you just have to know another Data Dictionary Table USER_TAB_COLUMNS.

SELECT count(*)
from USER_TAB_COLUMNS
where table_name = 'EMP';





Happy Reading........

 

Comments

Unknown said…
Hello sir..i have a query..actually i was using ORACLE 10G software for SQL in my windows 7, 64 bit...at first it was working properly but after some time i was not able to use it and started getting an error i.e. ORA-01033: ORACLE initialization and shutdown in progress.
June 16, 2015 at 8:41 PM
Unknown said…
What should i do to fix it and i have re-installed it many times..
is there any other way to fix this problem ?
June 16, 2015 at 8:43 PM
Post a Comment

Popular posts from this blog

SQL Interview Questions on Subqueries

SUB Queries:
1. List the employees working in research department 2. List employees who are located in New York and Chicago
3. Display the department name in which ANALYSTS are working
4. Display employees who are reporting to JONES
5. Display all the employees who are reporting to Jones Manager
6. Display all the managers in SALES and ACCOUNTING department
7. Display all the employee names in Research and Sales Department who are having at least 1 person reporting to them
8. Display all employees who do not have any reportees
9. List employees who are having at least 2 reporting
10. List the department names which are having more than 5 employees
11. List department name having at-least 3 salesman
12. List employees from research and accounting having at-least 2 reporting
13. Display second max salary
14. Display 4th max salary
15. Display 5th max salary  -- Answer for nth Max Salary
Co-Related Subqueries:
16. Write a query to get 4th max salary from EMP table
17. Write a query to get 2nd…
21 comments
Read more

Basics of RDBMS

Data
Small set of information becomes data, this set of information helps make decision. Data is always some useful information.


Database
Place where you store the data. Database represents some aspect of the real world called "miniworld". A database is designed, built and populated with data for a specific purpose. It has intended group of users and some preconceived applications in which these users are interested.

In other words, a database has some source from which data is derived, some degree of interaction with events in the real world and an audience that is actively interested in the contents of the database.

Database can also be defined as collection of one or more tables.

Ex: Mobile, human brain etc



DBMS (Database Management System)
Is a program that stores retrieves and modifies data in the database on request.

Study of different techniques of design, development and maintenance of the database

Types of DBMS
These types are based upon their management of database s…
101 comments
Read more

Answers for SQL Functions

1. SQL> SELECT empno, ename FROM emp WHERE Length(ename) = 4;

2. SQL> SELECT empno, ename, job FROM emp where Length(job)=7;

3. SQL> SELECT Length('qspiders') - Length(replace('qspiders','s','')) FROM dual;

4. SQL>  SELECT empno, ename, job FROM emp WHERE Instr(job,'MAN') >0;

5. SQL> SELECT empno, ename, job FROM emp WHERE Instr(job, 'MAN') =1;

6. SQL> SELECT empno, ename, job FROM emp WHERE (Length(ename) - Length(Replace(ename, 'L',''))) = 1;

7. SQL> SELECT * FROM dept WHERE Instr(dname,'O') > 0;

8. SQL> SELECT Concat(ename,' working as a ') || Concat(job, ' earns ') || Concat(sal, '  in ') || Conc
at('dept ',deptno) AS text from emp;

OR

SQL> SELECT Concat(Concat(Concat(Concat(Concat(Concat(Concat(ename,' working as a '), job),' earns '), sal),'  in '),'dept '), deptno) AS text FROM emp;

9. SQL> SELECT empno, ename…
40 comments
Read more