MySQL

0 / 100 solved · Easy 27 · Medium 45 · Hard 28

#		Title	Difficulty
1	○	Weekly Message Histogram	Easy
2	○	Candidates With Every Required Skill	Easy
3	○	Products With No Purchases	Easy
4	○	Incomplete Assembly Jobs	Easy
5	○	Desktop vs Mobile Sessions	Easy
6	○	User Posting Span	Easy
7	○	Top Chat Contributors	Easy
8	○	Repeated Job Descriptions	Easy
9	○	Cities With Most Completed Trades	Easy
10	○	Monthly Product Rating	Easy
11	○	Employees Paid More Than Their Manager	Easy
12	○	End-of-Day Wallet Balance	Easy
13	○	Campaign Click-Through Rate	Easy
14	○	Confirmed the Next Day	Easy
15	○	Active Database Products	Easy
16	○	Card Issuance Range	Easy
17	○	Average From a Frequency Table	Easy
18	○	Drug Profit by Product	Easy
19	○	Loss-Making Manufacturers	Easy
20	○	Manufacturer Revenue Summary	Easy
21	○	Callers With Repeat Support Contacts	Easy
22	○	Customers Who Never Ordered	Easy
23	○	Daily Unique Likers	Easy
24	○	Department Maximum Salary	Easy
25	○	Low-Engagement Customers	Easy
26	○	Third Completed Purchase	Medium
27	○	Second Distinct Salary	Medium
28	○	Send vs Open Share by Age Group	Medium
29	○	Three-Day Rolling Post Average	Medium
30	○	Top Two Products per Category	Medium
31	○	Top Three Salaries per Department	Medium
32	○	Signup Activation Rate	Medium
33	○	Listening History With Running Total	Medium
34	○	Customers Using Every Product Family	Medium
35	○	Odd vs Even Readings Per Day	Medium
36	○	Repair Swapped Delivery Labels	Medium
37	○	Monthly Stock High and Low	Medium
38	○	Best Seller by Month	Medium
39	○	Three-Day Shopping Streak	Medium
40	○	Purchase Frequency Histogram	Medium
41	○	Mode From Compressed Counts	Medium
42	○	Launch Month Growth	Medium
43	○	International Call Share	Medium
44	○	High-Frequency Support Users	Medium
45	○	Seven-Day Login Streak	Medium
46	○	Day-7 Retention by Signup Week	Medium
47	○	DAU to WAU Ratio	Medium
48	○	Signup Funnel by Cohort	Hard
49	○	Repeat Purchase Within 30 Days	Medium
50	○	Month-over-Month Revenue Growth	Medium
51	○	Month-1 and Month-2 Cohort Retention	Medium
52	○	First and Last Marketing Touch	Medium
53	○	Subscribers Active at Month End	Medium
54	○	Overlapping Room Bookings	Medium
55	○	Sessionize a Clickstream	Hard
56	○	Median Order Value by Country	Hard
57	○	95th Percentile API Latency	Hard
58	○	Keep the Latest Customer Record	Easy
59	○	Login Islands	Medium
60	○	Monthly Top Seller	Medium
61	○	Seven-Day Moving Spend	Hard
62	○	Revenue Pareto Share	Medium
63	○	Friend Acceptance Rate by Month	Medium
64	○	Notification Opt-In Conversion	Medium
65	○	Users Who Both Buy and Sell	Medium
66	○	Two-Month Inactivity Churn	Hard
67	○	Experiment Conversion Summary	Hard
68	○	Net Revenue After Refunds	Easy
69	○	Delivery SLA Percentiles	Hard
70	○	Cancellation Rate With the Right Denominator	Medium
71	○	Potential Duplicate Payments	Medium
72	○	Time to Second Purchase	Medium
73	○	Average Interpurchase Time	Medium
74	○	Stockout Duration	Hard
75	○	Effective Price at Purchase	Medium
76	○	Monthly Active User Retention	Hard
77	○	Year-over-Year Monthly Growth	Hard
78	○	Pack Premium Bundles Into Warehouses	Hard
79	○	Median Search Count From a Histogram	Hard
80	○	Advertiser Lifecycle Status	Hard
81	○	Three Consecutive Filing Years	Medium
82	○	Cross-Channel Touch Streak	Hard
83	○	Three-Item Bundle Revenue	Hard
84	○	Escalation After Repeated Contacts	Medium
85	○	Reactivated After 90 Days	Medium
86	○	Senior Management Span	Hard
87	○	Server Busy Time From Start and Stop Events	Hard
88	○	Repeated Payment Clusters	Hard
89	○	Cohort Retention Matrix	Hard
90	○	Rolling 30-Day Unique Users	Medium
91	○	Longest Activity Streak per User	Hard
92	○	Last Non-Direct Attribution	Medium
93	○	Type-2 Dimension Lookup	Medium
94	○	Merge Overlapping Subscription Intervals	Hard
95	○	Spend Spike Against a Prior Baseline	Hard
96	○	Shared-Device Merchant Rings	Hard
97	○	Referral Tree Revenue	Hard
98	○	Ordered Funnel Completion	Hard
99	○	Monthly Survival Retention Curve	Hard
100	○	Recency-Weighted Multi-Touch Attribution	Hard