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Recap - Membership

Part of the Beyond the Basics section of Coddy's SQL journey. Lesson 19 of 27.

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Challenge

Easy

Available tables and columns:

  • signup_2025: user_id
  • signup_2026: user_id

Return one column user_id containing the IDs of users who signed up in 2025 but not 2026: these are users who didn't renew. Order ascending.

Try it yourself

-- 2025 ids minus 2026 ids

All lessons in Beyond the Basics

1Conditional Logic

CASE WHENCASE in ORDER BYCOALESCE for NULLsNULLIF and IIFRecap - Attendance

4Set Operations

UNION vs UNION ALLINTERSECTEXCEPTRecap - Membership

2String Functions

LENGTH, UPPER, LOWERSUBSTRINSTRREPLACE and TRIMConcatenating with ||Recap - Invoices

5Recursive CTEs

A Number SequenceWalking a HierarchyRecap - Org Chart

3Conditional Aggregation

COUNT with CASESUM with CASEPivoting Rows to ColumnsRecap - Traffic Sources

6Analytics Recipes

Top-N per GroupPercentage of TotalRunning TotalKeeping One Row per KeyRecap - Top Customers

Practice on your own: SQL playground