Filtering with WHERE

The WHERE clause in SQL is used to filter rows based on a condition.

Rather than returning all records in a table, WHERE lets you retrieve only the rows that meet your criteria.

Here's the structure of a SELECT query using WHERE:

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SELECT column1, column2
FROM table_name
WHERE condition;

• SELECT specifies the columns to display
• FROM selects the table to query
• WHERE filters for rows that match a given condition

Let's say the teacher wants a list of students who scored above 90 on the final exam:

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SELECT name, exam_score
FROM final_exam
WHERE exam_score > 90;

This would return:

You can use many operators in the WHERE clause:

• = equal to
• != or <> not equal to
• > greater than
• < less than
• >= greater than or equal to
• <= less than or equal to

You can also combine multiple conditions using AND, OR, and NOT.

Filtering data helps you answer real questions, such as:

• Which students passed the exam?
• Who scored above 90?
• What records match specific criteria?

WHERE gives you control over your queries and helps you explore meaningful patterns in data.

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SELECT name, passed
FROM final_exam
WHERE passed = 'Yes';

This query returns the students who passed the final exam: