INTERACTIVE LECTURES

Build and change a database

Guided class activity · apply the ideas from the full SQL lessons.

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Detailed lessons in this module

Open the full explanations, examples, and SQL exercises directly.

13Lecture 13: Inserting RowsDisposable movie fixture · 2 exercises 14Lecture 14: Updating RowsDisposable movie fixture · 3 exercises 15Lecture 15: Deleting RowsDisposable movie fixture · 2 exercises 16Lecture 16: Creating TablesEmpty database → your new table · 2 exercises 17Lecture 17: Altering TablesDisposable table-alteration fixture · 3 exercises 18Lecture 18: Dropping TablesDisposable table-removal fixture · 3 exercises

Module overview & notes →All interactive lectures

Preparing for Lab 10 · After practice, try the team challenge.

Opening your saved work…

Preview before changing rows

Step 1 of 9 · Database: Northshore Coffee

READ & UNDERSTAND

INSERT adds rows, UPDATE changes values, and DELETE removes rows. Before an UPDATE or DELETE, use a SELECT with the same WHERE condition to inspect its intended scope.

A missing WHERE can affect every row. A syntactically valid statement can therefore be a serious reasoning error. State what should remain unchanged and plan a query to check it.

This preview activity is read-only. The row-change workshops linked below use disposable exercise fixtures and check the resulting data, so you can safely practice the actual statements there.

Worked example

SELECT id, name, price FROM menu_items WHERE price < 4 ORDER BY id;

This SELECT previews the rows below four dollars. It cannot change any prices, so it is a useful first check before an UPDATE.

For the practice task, add both category and price restrictions. The verification plan should include qualifying rows and a sample or full comparison of rows that must remain unchanged.

Your question

Return id, name, and price for Tea items priced below 5, ordered by id. This is the scope preview for a proposed price change.

Predict the result

Explain your evidence

Which unchanged rows would you inspect afterward, and why is checking only the changed count insufficient?

Try a query to unlock the worked-answer discussion.

Table & column names only · ↑ ↓ choose · Tab insert · Esc dismiss

Query results

Predict the result, then run your query.

Read-only activity · One statement per run · First 200 rows displayed · Checks compare the complete bounded result, not just this preview.

Explore this query freely in the playground ↗

Check the save status above. Account-saved work is available in My Progress. Explanations are for discussion, not automatically graded. No prerequisite locks.