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Sometimes customers who register online are actually existing store members. In this case, we need to avoid duplicate registration and link to existing customer information.
Why Duplicates Occur
Typical Scenarios
| Case | Past | Today | Problem |
|---|---|---|---|
| Store member registers online | Created membership card at store (POS member #: 00001) | Registers online with same email | Same person but registered as different member? |
| Online member visits store | Registered online (Shopify ID: 12345) | Asked to register at store | Register as new POS member? Points split? |
Store member registers online
PastCreated membership card at store (POS member #: 00001)
TodayRegisters online with same email
ProblemSame person but registered as different member?
Online member visits store
PastRegistered online (Shopify ID: 12345)
TodayAsked to register at store
ProblemRegister as new POS member? Points split?
Problems Caused by Duplicates
| Problem | Impact |
|---|---|
| Split points | Points accumulate separately online and in-store |
| Fragmented purchase history | Cannot analyze same person's purchase trends |
| Customer support confusion | Need to ask 'Which member number?' |
| Reduced marketing efficiency | Sending duplicate DMs to same person |
Split points
ImpactPoints accumulate separately online and in-store
Fragmented purchase history
ImpactCannot analyze same person's purchase trends
Customer support confusion
ImpactNeed to ask 'Which member number?'
Reduced marketing efficiency
ImpactSending duplicate DMs to same person
Duplicate Detection Logic
Matching by Email Address
This project uses email address as the primary key for duplicate detection.
Receive registration request
Customer submits online membership registration form
Check existing in POS
Search POS customer database with entered email address
Branch based on result
Different processing for existing customer found vs. not found
Integrate or create new
If exists -> Update member number to link, If not -> Register as completely new
Existing Customer Check Flow
Check existing customers by email
Receive online registration request
Email address: yamada@example.com
Search email in POS
Found -> Get existing POS customer ID / Not found -> Create completely new POS customer
Update member number with Shopify ID
Now POS customer can be identified by Shopify ID
Why Match by Email Address
Comparison of Matching Keys
| Key | Uniqueness | Change Frequency | Ease of Acquisition | Adoption |
|---|---|---|---|---|
| Email address | High | Low | Easy | Adopted |
| Phone number | Moderate | Moderate | Easy | Sub-key |
| Name | Low | Low | Easy | Supplementary only |
| Address | Moderate | High | Easy | Supplementary only |
Email address
UniquenessHigh
Change FrequencyLow
Ease of AcquisitionEasy
AdoptionAdopted
Phone number
UniquenessModerate
Change FrequencyModerate
Ease of AcquisitionEasy
AdoptionSub-key
Name
UniquenessLow
Change FrequencyLow
Ease of AcquisitionEasy
AdoptionSupplementary only
Address
UniquenessModerate
Change FrequencyHigh
Ease of AcquisitionEasy
AdoptionSupplementary only
Advantages of Email Address
- Required in both systems: Both Shopify and POS have email addresses
- Low duplication: Rare for same email to be used by multiple people
- Low change frequency: Changes less often than phone numbers
- Fast searching: Easy to index
Existing Member Update Process
What Gets Updated
When an existing POS member is found, the member number is overwritten.
Only the member number is updated; other information and point balance are preserved.
Why Only Update Member Number
- Preserve points: Don't lose existing point balance
- Preserve purchase history: Past purchase history remains intact
- Establish link: Can now search by Shopify ID
Edge Cases to Consider
Edge Cases and Solutions
| Case | Problem | Solution |
|---|---|---|
| Customer changed email | Registers online with different email than store registration -> Treated as different person | Store staff updates email in POS, or customer reports email change to store |
| Family using same email | Husband registered at store, wife registers online -> Considered same person and linked | Show 'This email is already registered' and encourage registration with different email |
| Multiple POS customers with same email | Data entry errors caused duplicates -> Cannot determine which to link | Link to first found customer, log warning, admin reviews and merges later |
Customer changed email
ProblemRegisters online with different email than store registration -> Treated as different person
SolutionStore staff updates email in POS, or customer reports email change to store
Family using same email
ProblemHusband registered at store, wife registers online -> Considered same person and linked
SolutionShow 'This email is already registered' and encourage registration with different email
Multiple POS customers with same email
ProblemData entry errors caused duplicates -> Cannot determine which to link
SolutionLink to first found customer, log warning, admin reviews and merges later
Benefits of This System
For Customers
- Points earned at store can be viewed online
- No need to re-enter member information
- Recognized as "the same person" across all channels
For Operations
- No confusion from duplicate data
- Can see complete customer picture (online + store)
- Reduced complaint handling effort