Set Operations

Redis Set is an unordered collection of unique strings, suitable for storing unique values.

SAdd - Add Set Members

Add Single Member

oRedis.SAdd "myset", "apple"

Add Multiple Members

oRedis.SAdd "myset", "banana", "orange", "grape"

Note: Sets automatically deduplicate, adding duplicate elements will only keep one.

SMembers - Get All Set Members

' Get all members
Dim vMembers As Variant
vMembers = oRedis.SMembers("myset")

If IsArray(vMembers) Then
    Dim i As Long
    For i = 0 To UBound(vMembers)
        Debug.Print vMembers(i)
    Next
End If

SCard - Get Set Member Count

Dim lCount As Long
lCount = oRedis.SCard("myset")
Debug.Print "Set member count: " & lCount

SIsMember - Check if Member Exists

If oRedis.SIsMember("myset", "apple") Then
    Debug.Print "Member exists"
Else
    Debug.Print "Member does not exist"
End If

SRem - Delete Set Members

' Delete single member
oRedis.SRem "myset", "apple"

' Delete multiple members
oRedis.SRem "myset", "banana", "orange"

Use Cases

1. Article Tags

Sub ArticleTags()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sArticleId As String
    sArticleId = "post:1:tags"

    ' Add tags
    oRedis.SAdd sArticleId, "Technology", "Programming", "Redis", "VB6", "Database"

    ' Check tag count
    Debug.Print "Article tags count: " & oRedis.SCard(sArticleId)

    ' Check if specific tag exists
    If oRedis.SIsMember(sArticleId, "Redis") Then
        Debug.Print "This article contains Redis tag"
    End If

    ' Get all tags
    Dim vTags As Variant
    vTags = oRedis.SMembers(sArticleId)

    Debug.Print vbCrLf & "All tags:"
    Dim i As Long
    If IsArray(vTags) Then
        For i = 0 To UBound(vTags)
            Debug.Print "  - " & vTags(i)
        Next
    End If

    ' Delete specific tag
    oRedis.SRem sArticleId, "VB6"
    Debug.Print vbCrLf & "After deleting tag, remaining tags count: " & oRedis.SCard(sArticleId)

    oRedis.DisConnect
End Sub

2. User Following

Sub UserFollowers()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sUserId As String
    sUserId = "user:123"

    ' Users this user follows
    oRedis.SAdd sUserId & ":following", "user:456", "user:789", "user:101"

    ' Users following this user
    oRedis.SAdd sUserId & ":followers", "user:200", "user:300", "user:400"

    ' Check if following specific user
    If oRedis.SIsMember(sUserId & ":following", "user:456") Then
        Debug.Print "Already following user 456"
    End If

    ' Get following list
    Dim vFollowing As Variant
    vFollowing = oRedis.SMembers(sUserId & ":following")

    Debug.Print vbCrLf & "Following list:"
    Dim i As Long
    If IsArray(vFollowing) Then
        For i = 0 To UBound(vFollowing)
            Debug.Print "  " & vFollowing(i)
        Next
    End If

    ' Get follower count
    Debug.Print vbCrLf & "Follower count: " & oRedis.SCard(sUserId & ":followers")

    ' Unfollow
    oRedis.SRem sUserId & ":following", "user:789"
    Debug.Print "After unfollowing, following count: " & oRedis.SCard(sUserId & ":following")

    oRedis.DisConnect
End Sub

3. Online Users

Sub OnlineUsers()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sOnlineSet As String
    sOnlineSet = "users:online"

    ' Users come online
    oRedis.SAdd sOnlineSet, "user:1001", "user:1002", "user:1003", "user:1004"

    ' Get online user count
    Debug.Print "Online users count: " & oRedis.SCard(sOnlineSet)

    ' Check if specific user is online
    If oRedis.SIsMember(sOnlineSet, "user:1001") Then
        Debug.Print "User 1001 is online"
    End If

    ' Get all online users
    Dim vUsers As Variant
    vUsers = oRedis.SMembers(sOnlineSet)

    Debug.Print vbCrLf & "Online user list:"
    Dim i As Long
    If IsArray(vUsers) Then
        For i = 0 To UBound(vUsers)
            Debug.Print "  " & vUsers(i)
        Next
    End If

    ' User goes offline
    oRedis.SRem sOnlineSet, "user:1002"
    Debug.Print vbCrLf & "User 1002 offline, online users count: " & oRedis.SCard(sOnlineSet)

    oRedis.DisConnect
End Sub

4. IP Blacklist

Sub IpBlacklist()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sBlacklist As String
    sBlacklist = "security:blacklist"

    ' Add IP to blacklist
    oRedis.SAdd sBlacklist, "192.168.1.100"
    oRedis.SAdd sBlacklist, "192.168.1.101"
    oRedis.SAdd sBlacklist, "192.168.1.102"

    ' Check if IP is in blacklist
    Dim sCheckIp As String
    sCheckIp = "192.168.1.100"

    If oRedis.SIsMember(sBlacklist, sCheckIp) Then
        Debug.Print "IP " & sCheckIp & " is in blacklist, access denied"
    Else
        Debug.Print "IP " & sCheckIp & " can access"
    End If

    ' Get all IPs in blacklist
    Dim vIps As Variant
    vIps = oRedis.SMembers(sBlacklist)

    Debug.Print vbCrLf & "IPs in blacklist:"
    Dim i As Long
    If IsArray(vIps) Then
        For i = 0 To UBound(vIps)
            Debug.Print "  " & vIps(i)
        Next
    End If

    ' Remove IP from blacklist
    oRedis.SRem sBlacklist, "192.168.1.101"
    Debug.Print vbCrLf & "Removed 192.168.1.101 from blacklist"

    oRedis.DisConnect
End Sub

5. Unique Visitor Statistics

Sub UniqueVisitors()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sDate As String
    sDate = "2024-01-01"
    Dim sVisitorKey As String
    sVisitorKey = "stats:visitors:" & sDate

    ' Record visitor IDs
    oRedis.SAdd sVisitorKey, "visitor:001"
    oRedis.SAdd sVisitorKey, "visitor:002"
    oRedis.SAdd sVisitorKey, "visitor:003"

    ' Same visitor visits again (will not count again)
    oRedis.SAdd sVisitorKey, "visitor:001"
    oRedis.SAdd sVisitorKey, "visitor:002"

    ' Get unique visitor count for the day
    Debug.Print sDate & " unique visitors: " & oRedis.SCard(sVisitorKey)

    ' Get all visitor IDs
    Dim vVisitors As Variant
    vVisitors = oRedis.SMembers(sVisitorKey)

    Debug.Print vbCrLf & "Visitor list:"
    Dim i As Long
    If IsArray(vVisitors) Then
        For i = 0 To UBound(vVisitors)
            Debug.Print "  " & vVisitors(i)
        Next
    End If

    oRedis.DisConnect
End Sub

6. Bookmarks

Sub Bookmarks()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then Exit Sub

    Dim sUserId As String
    sUserId = "user:123"
    Dim sBookmarksKey As String
    sBookmarksKey = sUserId & ":bookmarks"

    ' Add bookmarks
    oRedis.SAdd sBookmarksKey, "article:1"
    oRedis.SAdd sBookmarksKey, "article:2"
    oRedis.SAdd sBookmarksKey, "article:3"

    ' Check if article is bookmarked
    If oRedis.SIsMember(sBookmarksKey, "article:1") Then
        Debug.Print "Article 1 is bookmarked"
    End If

    ' Get bookmark count
    Debug.Print "Bookmark count: " & oRedis.SCard(sBookmarksKey)

    ' Get all bookmarks
    Dim vBookmarks As Variant
    vBookmarks = oRedis.SMembers(sBookmarksKey)

    Debug.Print vbCrLf & "Bookmark list:"
    Dim i As Long
    If IsArray(vBookmarks) Then
        For i = 0 To UBound(vBookmarks)
            Debug.Print "  " & vBookmarks(i)
        Next
    End If

    ' Remove bookmark
    oRedis.SRem sBookmarksKey, "article:2"
    Debug.Print vbCrLf & "After removing bookmark, remaining count: " & oRedis.SCard(sBookmarksKey)

    oRedis.DisConnect
End Sub

Complete Example

Sub Example_SetOperations()
    Dim oRedis As New cRedisClient

    If Not oRedis.Connect() Then
        Debug.Print "Connection failed: " & oRedis.LastError
        Exit Sub
    End If

    ' Use Set to store tags
    oRedis.SAdd "post:1:tags", "Technology", "Programming", "Redis", "VB6"

    Debug.Print "Article tags count: " & oRedis.SCard("post:1:tags")

    Dim vTags As Variant
    vTags = oRedis.SMembers("post:1:tags")

    Debug.Print "All tags:"
    Dim i As Long
    For i = 0 To UBound(vTags)
        Debug.Print "  - " & vTags(i)
    Next

    ' Check if tag exists
    If oRedis.SIsMember("post:1:tags", "Redis") Then
        Debug.Print vbCrLf & "Contains Redis tag"
    End If

    ' Delete tag
    oRedis.SRem "post:1:tags", "VB6"
    Debug.Print "After deleting tag, remaining tags count: " & oRedis.SCard("post:1:tags")

    ' Add again (will not duplicate)
    oRedis.SAdd "post:1:tags", "Programming"
    Debug.Print "After adding 'Programming' again, tags count: " & oRedis.SCard("post:1:tags")

    oRedis.DisConnect
End Sub

Set vs List Selection

Scenario	Recommended Type	Reason
Need unique values	Set	Automatic deduplication
Allow duplicates	List	Can store duplicate elements
Member check	Set	O(1) time complexity
Store in order	List	Maintain insertion order
Deduplication needed	Set	Sets naturally support dedup
Stack/Queue	List	Supports LPush/LPop/RPush/RPop

Set Features

1. Unordered: Members have no order
2. Unique: Duplicate elements not allowed
3. Fast lookup: Very fast to check member existence
4. Set operations: Supports intersection, union, difference operations (requires extended implementation)