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 [...]

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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 [...]

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