Practice Arena

412 problems across 3 datasets

#	Title	Dataset	Difficulty	Category
1	List All Products	E-Commerce	easy	SELECT
2	Customers from a Specific State	E-Commerce	easy	WHERE
3	High-Value Completed Orders	E-Commerce	easy	WHERE
4	Products in a Price Range	E-Commerce	easy	WHERE
5	Search Products by Name	E-Commerce	easy	WHERE
6	Ten Most Recent Orders	E-Commerce	easy	SELECT
7	Unique Customer Cities	E-Commerce	easy	SELECT
8	Orders by Status	E-Commerce	easy	WHERE
9	Total Number of Orders	E-Commerce	easy	Aggregation
10	Total Revenue by Category	E-Commerce	easy	Aggregation
11	Average Order Value	E-Commerce	easy	Aggregation
12	Orders Per Customer	E-Commerce	easy	Aggregation
13	Highest and Lowest Priced Products	E-Commerce	easy	Aggregation
14	Categories with Many Products	E-Commerce	medium	Aggregation
15	Monthly Order Count	E-Commerce	medium	Aggregation
16	Average Rating Per Product	E-Commerce	medium	Aggregation
17	Order Details with Customer Name	E-Commerce	easy	Joins
18	Products with Category Names	E-Commerce	easy	Joins
19	Customers Who Never Ordered	E-Commerce	medium	Joins
20	Order Items with Full Details	E-Commerce	medium	Joins
21	Orders with Payment and Shipping Status	E-Commerce	medium	Joins
22	Customer Order Summary	E-Commerce	medium	Joins
23	Products Never Reviewed	E-Commerce	medium	Joins
24	Customers Who Reviewed Their Purchases	E-Commerce	hard	Joins
25	Products Priced Above Average	E-Commerce	medium	Subqueries
26	High-Spending Customers	E-Commerce	medium	Subqueries
27	Most Expensive Product Per Category	E-Commerce	medium	Subqueries
28	Customers Who Ordered from Every Category	E-Commerce	hard	Subqueries
29	Products Ordered but Never Reviewed	E-Commerce	hard	Subqueries
30	Orders Above Customer's Own Average	E-Commerce	hard	Subqueries
31	Rank Products by Price Within Category	E-Commerce	medium	Window Functions
32	Customer Order Sequence Numbers	E-Commerce	medium	Window Functions
33	Running Total of Daily Revenue	E-Commerce	hard	Window Functions
34	Compare Order Value to Previous Order	E-Commerce	hard	Window Functions
35	Dense Rank Customers by Total Spending	E-Commerce	hard	Window Functions
36	Monthly Revenue Report with CTE	E-Commerce	hard	CTEs
37	Revenue Pivot by Payment Method	E-Commerce	hard	Advanced
38	Average Delivery Time by Carrier	E-Commerce	hard	Advanced
39	Top 3 Best-Selling Products Per Category	E-Commerce	hard	Advanced
40	Customer Cohort Analysis by First Purchase Month	E-Commerce	hard	Advanced
41	Count Customers per Country	E-Commerce	easy	Aggregation
42	Products Never Ordered	E-Commerce	easy	Joins
43	Average Order Value by Status	E-Commerce	easy	Aggregation
44	Orders with Customer Names	E-Commerce	easy	Joins
45	Distinct Shipping Carriers	E-Commerce	easy	SELECT
46	Total Revenue per Product Category	E-Commerce	medium	Joins
47	Customers with Multiple Orders	E-Commerce	easy	Aggregation
48	Payment Method Distribution	E-Commerce	easy	Aggregation
49	Products Above Average Price	E-Commerce	easy	Subqueries
50	Monthly Order Count	E-Commerce	easy	Aggregation
51	Top 10 Spending Customers	E-Commerce	easy	Aggregation
52	Order Items with Discounts Applied	E-Commerce	easy	SELECT
53	Customers Who Never Left a Review	E-Commerce	easy	Subqueries
54	Average Shipping Duration by Carrier	E-Commerce	medium	Aggregation
55	Revenue Impact of Discounts	E-Commerce	medium	Aggregation
56	Rank Products by Revenue Within Category	E-Commerce	medium	Window Functions
57	Running Total of Payments	E-Commerce	medium	Window Functions
58	Orders with the Most Line Items	E-Commerce	medium	Subqueries
59	Days Between Consecutive Customer Orders	E-Commerce	medium	Window Functions
60	Category Share of Total Revenue	E-Commerce	medium	Window Functions
61	Products with Average Rating and Review Count	E-Commerce	medium	Joins
62	Orders with Multiple Payments	E-Commerce	medium	Subqueries
63	Customers in the Same City	E-Commerce	medium	Joins
64	Each Customer's First Order	E-Commerce	medium	CTEs
65	Product Profit Margins	E-Commerce	medium	SELECT
66	Orders with Shipping Delays	E-Commerce	medium	Joins
67	Cumulative Monthly Revenue	E-Commerce	medium	Window Functions
68	Customers Who Bought from Every Category	E-Commerce	hard	Subqueries
69	3-Month Moving Average of Order Value	E-Commerce	hard	Window Functions
70	Delivered Orders Without Completed Payment	E-Commerce	medium	Joins
71	Budget-Friendly Products Under $10	E-Commerce	easy	WHERE
72	Customers Who Joined This Year	E-Commerce	easy	WHERE
73	Out-of-Stock Products	E-Commerce	easy	WHERE
74	Pending and Processing Orders	E-Commerce	easy	WHERE
75	Search Products by Name Keyword	E-Commerce	easy	WHERE
76	Average Order Value by Status	E-Commerce	medium	Aggregation
77	Top 5 Customers by Total Spend	E-Commerce	medium	Aggregation
78	Monthly Revenue Summary	E-Commerce	medium	Aggregation
79	Product Statistics per Category	E-Commerce	medium	Aggregation
80	Payment Method Breakdown	E-Commerce	medium	Aggregation
81	Customer Order History with Names	E-Commerce	medium	Joins
82	Order Line Items with Product Details	E-Commerce	medium	Joins
83	Product Catalog with Category Names	E-Commerce	medium	Joins
84	Orders with Shipping Status	E-Commerce	medium	Joins
85	Detailed Review Report	E-Commerce	medium	Joins
86	Products Priced Above Average	E-Commerce	medium	Subqueries
87	Customers Who Have Never Placed an Order	E-Commerce	medium	Subqueries
88	Most Expensive Product in Each Category	E-Commerce	medium	Subqueries
89	Orders Exceeding Customer's Own Average	E-Commerce	medium	Subqueries
90	Products with No Reviews	E-Commerce	medium	Subqueries
91	Rank Products by Price Within Category	E-Commerce	hard	Window Functions
92	Running Total of Daily Order Revenue	E-Commerce	hard	Window Functions
93	Customer Order Sequence Number	E-Commerce	hard	Window Functions
94	Top 3 Products per Category by Revenue	E-Commerce	hard	Window Functions
95	7-Day Moving Average of Order Amounts	E-Commerce	hard	Window Functions
96	Customer Lifetime Value Tiers	E-Commerce	hard	CTEs
97	Repeat Purchase Rate by Month	E-Commerce	hard	CTEs
98	Product Profit Margin Ranking	E-Commerce	hard	CTEs
99	Order Fulfillment Pipeline Report	E-Commerce	hard	CTEs
100	Month-over-Month Revenue Growth Rate	E-Commerce	hard	CTEs
101	RFM Customer Segmentation	E-Commerce	hard	Advanced
102	Market Basket: Frequently Co-Purchased Products	E-Commerce	hard	Advanced
103	Monthly Cohort Retention Analysis	E-Commerce	hard	Advanced
104	Inventory Reorder Alert with Sales Velocity	E-Commerce	hard	Advanced
105	Customer Churn Risk Scoring	E-Commerce	hard	Advanced
106	Count Delivered Orders	E-Commerce	easy	Aggregation
107	Customers with Missing Phone Numbers	E-Commerce	easy	Advanced
108	Customer Contact with COALESCE Fallback	E-Commerce	easy	Advanced
109	Classify Orders by Size	E-Commerce	easy	Advanced
110	Extract Year from Order Dates	E-Commerce	easy	Advanced
111	Uppercase Product Names	E-Commerce	easy	Advanced
112	Combine Cancelled and Returned Orders	E-Commerce	easy	Advanced
113	Customers Who Have Written Reviews	E-Commerce	easy	Advanced
114	Count Orders by Status Category	E-Commerce	easy	Aggregation
115	Customer Count by State	E-Commerce	easy	Advanced
116	Second Most Expensive Product	E-Commerce	easy	Advanced
117	Total Discount Amount Per Order	E-Commerce	easy	Aggregation
118	Total Revenue Per Customer with Name	E-Commerce	medium	Aggregation
119	Customers Spending Above Average	E-Commerce	medium	WHERE
120	Each Customer's Most Recent Order Amount	E-Commerce	medium	Advanced
121	Product Rating Breakdown with CASE	E-Commerce	medium	Aggregation
122	Average Days to Ship by Status	E-Commerce	medium	Advanced
123	Product Pairs in the Same Category	E-Commerce	medium	Advanced
124	Orders That Were Never Shipped	E-Commerce	medium	Advanced
125	Revenue Pivot by Payment Method Per Month	E-Commerce	medium	Advanced
126	Cumulative Spending Per Customer	E-Commerce	medium	Advanced
127	Top-Selling Category by Quantity	E-Commerce	medium	Advanced
128	Each Product's Share of Total Revenue	E-Commerce	medium	Advanced
129	Customers Using Multiple Payment Methods	E-Commerce	medium	Advanced
130	3-Order Moving Average Per Customer	E-Commerce	medium	Advanced
131	Rank Customers by Order Value with RANK and DENSE_RANK	E-Commerce	hard	Window Functions
132	Deduplicate Reviews with ROW_NUMBER	E-Commerce	hard	Advanced
133	Compare Each Order to Previous and Next	E-Commerce	hard	Advanced
134	Assign Customers to Spending Quartiles	E-Commerce	hard	Advanced
135	Multi-Step CTE: Customer Value Tiers	E-Commerce	hard	CTEs
136	Order Date Gap Analysis	E-Commerce	hard	Advanced
137	Monthly Cohort Retention Rate	E-Commerce	hard	Advanced
138	Customer Consecutive Order Month Streaks	E-Commerce	hard	Advanced
139	Refund Rate and Revenue Impact Analysis	E-Commerce	hard	Advanced
140	Recursive CTE: Order Value Tiers with Running Stats	E-Commerce	hard	CTEs
141	List All Branches	Finance	easy	SELECT
142	Customers in California	Finance	easy	WHERE
143	High-Balance Active Accounts	Finance	easy	WHERE
144	Accounts by Type	Finance	easy	WHERE
145	Search Transactions by Description	Finance	easy	WHERE
146	Ten Most Recent Transactions	Finance	easy	SELECT
147	Unique Customer Cities	Finance	easy	SELECT
148	Customers Without a Phone Number	Finance	easy	WHERE
149	Total Number of Accounts	Finance	easy	Aggregation
150	Total Balance by Account Type	Finance	easy	Aggregation
151	Average Loan Principal	Finance	easy	Aggregation
152	Transactions Per Account	Finance	easy	Aggregation
153	Minimum and Maximum Loan Interest Rates	Finance	easy	Aggregation
154	Account Types with Many Accounts	Finance	easy	Aggregation
155	Monthly Transaction Volume	Finance	easy	Aggregation
156	Average Account Balance by Status	Finance	easy	Aggregation
157	Customer Account List	Finance	medium	Joins
158	Customers with No Accounts	Finance	medium	Joins
159	Transaction Details with Customer Info	Finance	medium	Joins
160	Cards with Account Information	Finance	medium	Joins
161	Loan Payments with Customer Names	Finance	medium	Joins
162	Total Balance Per Customer	Finance	medium	Joins
163	Accounts with Card Count	Finance	medium	Joins
164	Customers in Branch Cities	Finance	medium	Joins
165	Accounts with Above-Average Balance	Finance	medium	Subqueries
166	Customers with Multiple Account Types	Finance	medium	Subqueries
167	Largest Transaction Per Account	Finance	medium	Subqueries
168	Customers with Defaulted Loans	Finance	medium	Subqueries
169	Accounts with No Transactions	Finance	medium	Subqueries
170	Loans Above Their Type Average	Finance	medium	Subqueries
171	Rank Accounts by Balance Within Type	Finance	hard	Window Functions
172	Running Transaction Total Per Account	Finance	hard	Window Functions
173	Identify Duplicate Customer Emails	Finance	hard	Window Functions
174	Previous Transaction Amount	Finance	hard	Window Functions
175	Account Balance Quartiles	Finance	hard	Window Functions
176	Customer Financial Summary with CTE	Finance	hard	CTEs
177	Monthly Deposits vs Withdrawals	Finance	hard	Advanced
178	Loan Payment Coverage Ratio	Finance	hard	Advanced
179	Multi-CTE Risk Report	Finance	hard	CTEs
180	Detect Suspicious Transaction Patterns	Finance	hard	Advanced
181	Number of Customers Per Branch City	Finance	easy	Joins
182	Customers with Both Checking and Savings	Finance	medium	Joins
183	Average Transaction Amount Per Customer	Finance	medium	Joins
184	Total Interest Paid by Loan Type	Finance	easy	Joins
185	Credit Card Utilization Rate	Finance	medium	Joins
186	Customers with Accounts in Multiple Branch States	Finance	hard	Joins
187	Closed Accounts with Remaining Balance	Finance	easy	WHERE
188	Customer Count by Age Group	Finance	medium	Aggregation
189	Largest Account Balance Per Customer	Finance	medium	Subqueries
190	Loan Portfolio Status Summary	Finance	easy	Aggregation
191	Customers with Any Frozen Account	Finance	easy	Joins
192	Expired Cards with Customer Info	Finance	medium	Joins
193	Deposit Volume by Day of Week	Finance	medium	Aggregation
194	Number of Cards Per Customer	Finance	medium	Joins
195	High-Value Savings Account Holders	Finance	easy	Joins
196	Dense Rank Customers by Total Balance	Finance	hard	Window Functions
197	Each Account as Percentage of Customer Total	Finance	hard	Window Functions
198	Next Payment Date for Each Loan Payment	Finance	hard	Window Functions
199	Accounts Opened on the Same Day as Another	Finance	medium	Subqueries
200	Customers Without Any Loans	Finance	easy	Subqueries
201	Monthly New Account Trend with CTE	Finance	medium	CTEs
202	Customer First and Last Transaction Dates	Finance	medium	Joins
203	Top Transaction Amount by Type (CTE)	Finance	medium	CTEs
204	Loan Repayment Progress Report	Finance	hard	CTEs
205	Transaction Type Pivot by Account	Finance	hard	Advanced
206	3-Transaction Moving Average	Finance	hard	Window Functions
207	Customer Lifetime Value Estimate	Finance	hard	CTEs
208	Customer Pairs in the Same City	Finance	medium	Joins
209	Combined Cash Inflow Report	Finance	medium	Advanced
210	Accounts Opened Before Their City Got a Branch	Finance	hard	Subqueries
211	Percent Rank of Account Balances	Finance	hard	Window Functions
212	Highest Balance Account per Type	Finance	hard	Window Functions
213	Top 3 Accounts by Balance Per Type	Finance	hard	Window Functions
214	Month-over-Month Transaction Growth Rate	Finance	hard	CTEs
215	Cumulative Loan Disbursements by Month	Finance	medium	Window Functions
216	Customers with Every Account Type	Finance	hard	Subqueries
217	Detect Payment Gaps Over 60 Days	Finance	hard	Window Functions
218	Account Balance Change Since Opening	Finance	medium	Subqueries
219	Transactions Above Account Type Average	Finance	medium	Subqueries
220	Customers with Active Loans but No Payments	Finance	medium	Joins
221	Savings Accounts with Balance Over 10000	Finance	easy	SELECT
222	List All Expired Cards	Finance	easy	SELECT
223	Large Transactions in the Last 30 Days	Finance	easy	SELECT
224	Customers Born in the 1990s	Finance	easy	SELECT
225	Average Loan Principal by Loan Type	Finance	medium	Aggregation
226	Monthly Transaction Count and Volume	Finance	medium	Aggregation
227	Branch with the Most Customer Accounts	Finance	medium	Aggregation
228	Total Interest Paid by Loan Type	Finance	medium	Aggregation
229	Customer Card Details Report	Finance	medium	Joins
230	Each Loan with Its Most Recent Payment	Finance	medium	Joins
231	Accounts That Have No Cards Issued	Finance	medium	Joins
232	Customer Total Balance with Branch Info	Finance	medium	Joins
233	Accounts with Balance Above Overall Average	Finance	medium	Subqueries
234	Customers Who Have Multiple Active Loans	Finance	medium	Subqueries
235	Highest Single Transaction per Customer	Finance	medium	Subqueries
236	Loans with Interest Rate Above Their Type Average	Finance	medium	Subqueries
237	Account Balance Quartile Classification	Finance	hard	Window Functions
238	Running Balance After Each Transaction	Finance	hard	Window Functions
239	Dense Rank Transactions by Amount per Account Type	Finance	hard	Window Functions
240	Customer Account Summary with Multiple CTEs	Finance	hard	CTEs
241	Recursive Loan Payment Schedule Projection	Finance	hard	CTEs
242	Customer Spending by Category (CTE with Percentages)	Finance	hard	CTEs
243	Loan Risk Classification with CASE	Finance	hard	Advanced
244	Customers with Both Accounts and Loans (EXISTS)	Finance	hard	Advanced
245	Executive Financial Dashboard Query	Finance	hard	Advanced
246	Active Checking Accounts	Finance	easy	WHERE
247	Total Deposits Per Account	Finance	easy	Aggregation
248	Customers by Email Domain	Finance	easy	WHERE
249	Count of Accounts Per Branch City	Finance	easy	Aggregation
250	List All Blocked Cards	Finance	easy	WHERE
251	Five Oldest Customer Accounts	Finance	easy	SELECT
252	Overdrawn Accounts	Finance	easy	WHERE
253	Loan Count by Status	Finance	easy	Aggregation
254	Total Fees Charged Per Account	Finance	easy	Aggregation
255	Credit Cards Ordered by Credit Limit	Finance	easy	SELECT
256	Customer Transaction Summary	Finance	medium	Joins
257	Monthly Deposit and Withdrawal Totals	Finance	medium	Aggregation
258	Loan Payment Progress Tracker	Finance	medium	Joins
259	Customers Holding Multiple Account Types	Finance	medium	Aggregation
260	Accounts with Above-Average Transaction Volume	Finance	medium	Subqueries
261	Average Balance by Branch City	Finance	medium	Joins
262	Largest Withdrawal Per Customer	Finance	medium	Subqueries
263	Dormant Accounts (No Recent Transactions)	Finance	medium	Subqueries
264	Customers Who Opened Accounts on the Same Day	Finance	medium	Joins
265	Average Days Between Loan Payments	Finance	medium	Advanced
266	Account Type Balance Share	Finance	medium	Subqueries
267	Each Customer's First Transaction	Finance	medium	Subqueries
268	Rank Customers by Net Worth	Finance	hard	Window Functions
269	Detect Three Consecutive Deposits	Finance	hard	Window Functions
270	Detect Suspicious Large Withdrawal Patterns	Finance	hard	Advanced
271	Portfolio Diversification Score	Finance	hard	Aggregation
272	Year-over-Year Account Balance Growth	Finance	hard	Window Functions
273	Per-Customer 3-Transaction Moving Average	Finance	hard	Window Functions
274	Account Cohort Activity Analysis	Finance	hard	Advanced
275	Account Balance Volatility Ranking	Finance	hard	Window Functions
276	Multi-CTE Financial Health Report	Finance	hard	CTEs
277	NTILE Customer Segmentation	Finance	hard	Window Functions
278	List All Patients	Healthcare	easy	SELECT
279	Patients from Texas	Healthcare	easy	WHERE
280	Completed Visits After a Date	Healthcare	easy	WHERE
281	Doctors in a Salary Range	Healthcare	easy	WHERE
282	Search Visits by Diagnosis	Healthcare	easy	WHERE
283	Patients with Missing Phone Numbers	Healthcare	easy	WHERE
284	Distinct Blood Types	Healthcare	easy	SELECT
285	Five Most Recent Patients	Healthcare	easy	SELECT
286	Count Patients by State	Healthcare	easy	Aggregation
287	Average Doctor Salary by Department	Healthcare	easy	Aggregation
288	Visit Count by Status	Healthcare	easy	Aggregation
289	Total Billing Amount by Status	Healthcare	easy	Aggregation
290	Top 10 Most Prescribed Medications	Healthcare	easy	Aggregation
291	Departments with More Than 4 Doctors	Healthcare	easy	Aggregation
292	Abnormal Lab Result Percentage	Healthcare	easy	Aggregation
293	Min and Max Billing Amounts	Healthcare	easy	Aggregation
294	Visits with Patient Names	Healthcare	medium	Joins
295	Doctors with Department Names	Healthcare	medium	Joins
296	Patients with Insurance Details	Healthcare	medium	Joins
297	Visit Details with Prescriptions	Healthcare	medium	Joins
298	Visit Count per Doctor	Healthcare	medium	Joins
299	Billing Records with Patient Info	Healthcare	medium	Joins
300	Lab Results with Visit and Patient Info	Healthcare	medium	Joins
301	Revenue per Department	Healthcare	medium	Joins
302	Doctors Earning Above Average	Healthcare	medium	Subqueries
303	Patients Who Have Never Visited	Healthcare	medium	Subqueries
304	Highest Single Bill per Department	Healthcare	medium	Subqueries
305	Patients with Multiple Different Diagnoses	Healthcare	medium	Subqueries
306	Visits Billed Above Department Average	Healthcare	hard	Subqueries
307	Doctors Who Have Every Visit Status	Healthcare	hard	Subqueries
308	Rank Doctors by Salary Within Department	Healthcare	hard	Window Functions
309	Running Total of Billing Amounts	Healthcare	hard	Window Functions
310	Days Between Consecutive Visits	Healthcare	hard	Window Functions
311	Top Billing Doctor per Department	Healthcare	hard	Window Functions
312	7-Day Moving Average of Daily Billing	Healthcare	hard	Window Functions
313	Patient Visit Summary with CTE	Healthcare	hard	CTEs
314	Find Duplicate Patient Emails	Healthcare	hard	Advanced
315	Department Budget Utilization	Healthcare	hard	Advanced
316	Monthly Visit Trends with CTEs	Healthcare	hard	CTEs
317	Comprehensive Doctor Scorecard	Healthcare	hard	Advanced
318	Count Patients per Blood Type	Healthcare	easy	Aggregation
319	Patients Without Insurance	Healthcare	easy	WHERE
320	Earliest and Latest Doctor Hire Dates	Healthcare	easy	Aggregation
321	Distinct Diagnoses	Healthcare	easy	SELECT
322	Average Billing Amount by Status	Healthcare	easy	Aggregation
323	Patient Visits with Doctor Names	Healthcare	easy	Joins
324	Top 5 Most Prescribed Medications	Healthcare	easy	Aggregation
325	Visits That Had Abnormal Lab Results	Healthcare	easy	Joins
326	Departments on Each Floor	Healthcare	easy	Aggregation
327	Prescriptions with High Refill Counts	Healthcare	easy	WHERE
328	Number of Unique Patients per Doctor	Healthcare	medium	Joins
329	Total Billing by Insurance Plan Type	Healthcare	medium	Joins
330	Doctors Earning Above Department Average	Healthcare	medium	Subqueries
331	Visit Count by Month and Year	Healthcare	medium	Aggregation
332	Patients with More Than 3 Visits	Healthcare	medium	Aggregation
333	Overdue Bills with Patient Contact Info	Healthcare	medium	Joins
334	Number of Lab Tests per Visit	Healthcare	medium	Joins
335	Diagnosis Frequency as Percentage	Healthcare	medium	Subqueries
336	Doctors with No Visits	Healthcare	medium	Joins
337	Prescription Duration in Days	Healthcare	medium	Advanced
338	Rank Doctors by Salary Within Specialty	Healthcare	medium	Window Functions
339	Running Total of Billing Amounts	Healthcare	medium	Window Functions
340	Patients Who Saw Multiple Doctors	Healthcare	medium	Aggregation
341	Visit Status Summary with CASE	Healthcare	medium	Advanced
342	Doctor Pairs in the Same Department	Healthcare	medium	Joins
343	Patients with All Visit Status Types	Healthcare	hard	Aggregation
344	Latest Visit per Patient Using ROW_NUMBER	Healthcare	hard	Window Functions
345	Visits with Above-Average Billing for Their Doctor	Healthcare	hard	Subqueries
346	Department Visit Statistics with CTE	Healthcare	hard	CTEs
347	Doctor Salary Quartiles with NTILE	Healthcare	medium	Window Functions
348	Patients Who Have At Least One Prescription	Healthcare	medium	Subqueries
349	Combined Doctor and Patient Contact List	Healthcare	medium	Advanced
350	Compare Each Bill to the Previous One	Healthcare	medium	Window Functions
351	Patient Out-of-Pocket vs Insurance Coverage	Healthcare	medium	Joins
352	Dense Rank Patients by Visit Frequency	Healthcare	medium	Window Functions
353	Patient Contact Info with COALESCE	Healthcare	easy	Advanced
354	Billing Aging Report with Multiple CTEs	Healthcare	hard	CTEs
355	Follow-Up Visit Chains	Healthcare	hard	Advanced
356	Percentile Rank of Doctor Salaries	Healthcare	hard	Window Functions
357	Patients with Visits but No Lab Results	Healthcare	medium	Advanced
358	Pivot Visit Counts by Status per Doctor	Healthcare	hard	Advanced
359	30-Day Readmission Rate by Department	Healthcare	hard	CTEs
360	7-Day Moving Average of Daily Billing	Healthcare	hard	Window Functions
361	Most Expensive Visit per Patient	Healthcare	medium	Subqueries
362	All Medications per Patient (Comma-Separated)	Healthcare	medium	Aggregation
363	Highest and Lowest Paid Doctor per Department	Healthcare	hard	Window Functions
364	Departments with Above-Average Doctor Count	Healthcare	medium	Subqueries
365	Complete Visit Detail Report	Healthcare	medium	Joins
366	Patient Journey Summary with CTEs	Healthcare	hard	CTEs
367	Cumulative Visit Count per Doctor Over Time	Healthcare	hard	Window Functions
368	High-Volume High-Revenue Doctors	Healthcare	medium	Aggregation
369	Visits Without Any Prescriptions (NOT EXISTS)	Healthcare	medium	Subqueries
370	Days Until Next Visit per Patient	Healthcare	hard	Window Functions
371	Doctor Revenue Ranking by Department (CTE + Window)	Healthcare	hard	CTEs
372	Patient Risk Categorization	Healthcare	hard	Advanced
373	Each Doctor's Share of Department Salary Budget	Healthcare	hard	Window Functions
374	Executive Dashboard Metrics with CTEs	Healthcare	hard	CTEs
375	Patient Count by Email Domain	Healthcare	easy	Advanced
376	Current Patient Age Calculation	Healthcare	easy	Advanced
377	Comprehensive Hospital Performance Report	Healthcare	hard	Advanced
378	Rank Doctors by Patient Count Within Each Department	Healthcare	hard	Window Functions
379	Patient Visit Summary with Diagnosis Counts and Billing	Healthcare	hard	CTEs
380	Patients Who Have Never Had a Prescription	Healthcare	medium	Subqueries
381	Department Performance Dashboard	Healthcare	hard	Advanced
382	Prescriptions with Patient, Doctor, and Diagnosis Details	Healthcare	medium	Joins
383	Male Patients Grouped by City	Healthcare	easy	Aggregation
384	Premium Insurance Plans with Low Copay	Healthcare	easy	WHERE
385	Doctor Count per Specialty	Healthcare	easy	Aggregation
386	Total Cancelled and No-Show Visits	Healthcare	easy	WHERE
387	Recent Abnormal Lab Results	Healthcare	easy	WHERE
388	Departments Ordered by Budget	Healthcare	easy	SELECT
389	Total Pending Billing Amount	Healthcare	easy	Aggregation
390	Patient Count by Birth Decade	Healthcare	easy	Aggregation
391	Prescriptions with Zero Refills	Healthcare	easy	WHERE
392	Visit Count by Day of Week	Healthcare	easy	Aggregation
393	Patient Visit History with Doctor Details	Healthcare	medium	Joins
394	Average Prescriptions per Visit by Doctor	Healthcare	medium	Joins
395	Billing Breakdown by Insurance Plan Type	Healthcare	medium	Joins
396	Department Visit Completion Rate	Healthcare	medium	Joins
397	Patients with Visits in Multiple Months	Healthcare	medium	Aggregation
398	Patient Out-of-Pocket Exceeding Insurance Coverage	Healthcare	medium	Joins
399	Abnormal Result Rate by Lab Test	Healthcare	medium	Aggregation
400	Patients with Visits Within 30 Days of a Previous Visit	Healthcare	medium	Joins
401	Most Common Diagnosis per Department	Healthcare	medium	Subqueries
402	Patients on Multiple Concurrent Medications	Healthcare	medium	Joins
403	Monthly Revenue with Month-over-Month Change	Healthcare	medium	Window Functions
404	Doctors Who Treated Every Blood Type	Healthcare	medium	Advanced
405	Visit Gap Analysis with Window Functions	Healthcare	hard	Window Functions
406	Department Composite Performance Ranking	Healthcare	hard	CTEs
407	Doctor Workload Percentile Ranking	Healthcare	hard	Window Functions
408	Complete Patient Journey Timeline	Healthcare	hard	CTEs
409	Cumulative Abnormal Lab Results per Patient Over Time	Healthcare	hard	Window Functions
410	Patient Cohort Retention Analysis	Healthcare	hard	CTEs
411	Doctor Revenue-to-Salary Efficiency Ratio	Healthcare	hard	CTEs
412	Hospital KPI Dashboard with Multiple CTEs	Healthcare	hard	CTEs