Comparison Operators
Comparison operators are how WHERE conditions actually compare values. You've already seen = and >; MySQL supports a full set. = checks equality (age = 16). != or <> checks "not equal" (age != 16). > and < check strictly greater than / less than. >= and <= check greater-than-or-equal and less-than-or-equal, which include the boundary value itself, unlike > and < alone. BETWEEN offers a clean shorthand for a range: WHERE age BETWEEN 15 AND 17; is equivalent to WHERE age >= 15 AND age <= 17;, but reads more clearly for an inclusive range. These operators work the same way whether you're comparing numbers, text, or dates though comparing text is typically alphabetical ("Ali" < "Sara" is true, because A comes before S), and comparing dates follows calendar order (earlier dates are "smaller").
Why this matters
- ·A rich set of comparison operators lets WHERE express precise, specific conditions.
- ·BETWEEN reads clearly for inclusive ranges, instead of writing two separate conditions.
- ·The same operators work consistently across numbers, text, and dates.
Common mistakes
- ·Confusing > with >= (or < with <=) silently excludes or includes a boundary value you didn't intend.
- ·BETWEEN is inclusive on both ends forgetting that can lead to off-by-one mistakes.
- ·Comparing values of mismatched types (like a number column to a quoted date-looking string) can behave unexpectedly.
+----+------+-----+ | id | name | age | +----+------+-----+ | 1 | Ali | 16 | +----+------+-----+ 1 row in set
PHP runs on a server, not in the browser this shows the expected output instead of a live one.
Frequently asked questions
> excludes the exact boundary value; >= includes it. age > 16 excludes students exactly 16, while age >= 16 includes them.
Practice questions
Question 1
Write a query that returns students with age not equal to 16.
PHP runs on a server, not in the browser this shows the expected output instead of a live one.
Question 2
Write a query that returns students with age between 14 and 18 using BETWEEN.
PHP runs on a server, not in the browser this shows the expected output instead of a live one.
Quick check
Just for this topic answer honestly, then check yourself.
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