ReadVitamin

What is a Derived Column

A derived column is a result of a calculation (most of the time mathematical) that happens during the SQL query processing and generates a new column which is not part of the original table definition. For example, in our table we have salary column present but when we want to extract a percentage of the salary or portion of the salary, we generally create a column on the fly with the mathematical calculation from the [+]

SELECT Query with Examples

In this Section we are going to try out all possible simple SELECT queries. First lets create a sample table called emp which should have rows like the following. emp_no dept_no first_name last_name salary 7000 114 Read Vitamin 62,000 4000 113 John Row 55,000 5000 114 Robert Howard 65,000 2000 112 Larry King 60,000 1000 112 Philip Josheph 65,000 6000 115 Tony Peter 72,000 3000 111 Micheal Reed 46,000 8000 113 Philip Josheph 65,000 9000 115 Tony Peter 72,000 1100 114 Micheal Reed 46,000 Follow this command to create a temporary table: CREATE SET VOLATILE TABLE emp, NO FALLBACK, CHECKSUM = DEFAULT, LOG ( "emp_no" INTEGER, "dept_no" VARCHAR (10), "first_name" CHAR (20) CHARACTER SET LATIN NOT CASESPECIFIC, "last_name" [+]