Abstract: in this instructional exercise, you will find out about the Oracle DUAL table which is a unique table utilized for assessing articulations or calling functions.

In Oracle, the SELECT proclamation must have a FROM provision. Be that as it may, some queries don’t require any table for example:

SELECT
   UPPER('This is a string')
FROM
   what_table

For this situation, you may consider making a table and utilize it in the FROM statement for simply utilizing the UPPER() work.

Problem 1: computer restarting multiple times.
Cause: software or Windows updates or a virus
Solution: Let the Windows updates Finish Windows updates alone can restart the computer many times and take a long time.
Run a virus scan
Problem 2:  Suddenly, applications or computer behaving abnormally.
For example, Software keeps crashing, missing files or runs slow.

Cause: virus infection or a hard drive going bad.
Solution: Run virus scan (check issue 4 for steps).   Check  Windows system logs for NTFS system errors or other HD related logs. Replace HD if necessary.
Problem 3: internet or website issue error: “404 pages not found”.
Cause: page is missing or deleted.  Wrong website link or website is down.

Summary: in this tutorial, you will learn how to use the Oracle SELECT statement to query data from a single table.

In Oracle, tables are consists of columns and rows. For example, the customers the table in the sample database has the following columns: customer_id, name, address, website and credit_limit. The  customers the table also has data in these columns.

To retrieve data from one or more columns of a table, you use them SELECT the statement with the following syntax: