A Guide to SQL
A Guide to SQL
9th Edition
ISBN: 9781111527273
Author: Philip J. Pratt
Publisher: Course Technology Ptr
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Chapter 4, Problem 9CAT
Program Plan Intro

“SELECT” command:

The “SELECT” command is used to retrieve data in a database.

Syntax for selecting values from the table is as follows:

SELECT STUDENT_ID FROM STUDENT;

  • The given query is used to display each student ID from “STUDENT” table.

“COUNT” function:

  • It is the one function of aggregate function.
  • The “COUNT” function is used to compute the number of rows in a table.

Example:

The example for “COUNT” function is given below:

SELECT COUNT(*) FROM STUDENT WHERE MARK_CREDIT >= 90;

The above query is used to display the number of students whose mark credit is greater or equal to “90” by using “COUNT” function.

  • From the given query, the asterisk (*) represent any column.
  • User can also count the number of rows in a query by selecting a particular column instead of using the asterisk.
    • The below example is as follows

      SELECT COUNT(STUDENT_ID) FROM STUDENT WHERE MARK_CREDIT >= 90;

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Chapter 4 Solutions

A Guide to SQL

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