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MySQL Tutorial - Evaluating Expressions with SELECT Statements

By: FYIcenter.com

(Continued from previous topic...)

How To Calculate Expressions with SELECT Statements?

There is no special SQL statements to calculate expressions. But you can use the "SELECT expression FROM DUAL" statement return the calculated value of an expression. "DUAL" is a dummy table in the server. The tutorial exercise below shows you some good examples:

SELECT 'Hello world!' FROM DUAL; 
   Hello world!

SELECT (1+2)*3/4 FROM DUAL;
   2.2500

SELECT TRUE FROM DUAL;
   1

SELECT TRUE AND FALSE FROM DUAL;
   0

SELECT TIME(SYSDATE()) FROM DUAL;
   21:30:26

(Continued on next topic...)

  1. What Is SQL Standard?
  2. How Many Groups of Data Types?
  3. What Are Character String Data Types?
  4. What Are the Differences between CHAR and NCHAR?
  5. What Are the Differences between CHAR and VARCHAR?
  6. What Are the Differences between BINARY and VARBINARY?
  7. What Are Numeric Data Types?
  8. What Are Date and Time Data Types?
  9. How To Calculate Expressions with SELECT Statements?
  10. How To Include Comments in SQL Statements?
  11. How To Include Character Strings in SQL statements?
  12. How To Escape Special Characters in SQL statements?
  13. How To Concatenate Two Character Strings?
  14. How To Include Numeric Values in SQL statements?
  15. How To Enter Characters as HEX Numbers?
  16. How To Enter Numeric Values as HEX Numbers?
  17. How To Enter Binary Numbers in SQL Statements?
  18. How To Enter Boolean Values in SQL Statements?
  19. What Are NULL Values?
  20. What Happens If NULL Values Are Involved in Expressions?
  21. How To Convert Numeric Values to Character Strings?
  22. How To Convert Character Strings to Numeric Values?
  23. How To Use IN Conditions?
  24. How To Use LIKE Conditions?
  25. How To Use Regular Expression in Pattern Match Conditions?
  26. How To Use CASE Expression?

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