erDiagram
    User ||--o{ Cred : "has credentials"
    User ||--o| Verify : "has verification"
    User ||--o| Profile : "has profile"
    Profile ||--o{ Avatar : "has avatar history"
    Avatar }o--|| Photo : "uses photo"
    User ||--o{ Follow : "follows"
    User ||--o{ Follow : "followed by"
    User ||--o{ Photo : "uploads"

    Country ||--o{ StateProvince : "has"
    StateProvince ||--o{ City : "has"

    User ||--o{ Brewery : "posts"
    Brewery ||--o| BreweryLoc : "has location"
    City ||--o{ BreweryLoc : "located in"
    Brewery ||--o{ BreweryPhoto : "has photos"
    Photo ||--o{ BreweryPhoto : "used in"

    User ||--o{ Beer : "posts"
    BeerStyle ||--o{ Beer : "categorizes"
    Brewery ||--o{ Beer : "brews"
    Beer ||--o{ BeerPhoto : "has photos"
    Photo ||--o{ BeerPhoto : "used in"
    Beer ||--o{ BeerComment : "has comments"
    User ||--o{ BeerComment : "comments"

    User {
        uniqueidentifier UserAccountID PK
        varchar Username UK
        nvarchar FirstName
        nvarchar LastName
        varchar Email UK
        datetime CreatedAt
        datetime UpdatedAt "nullable"
        date DateOfBirth
    }

    Cred {
        uniqueidentifier UserCredentialID PK
        uniqueidentifier UserAccountID FK
        datetime CreatedAt
        datetime Expiry
        nvarchar Hash
        bit IsRevoked
        datetime RevokedAt "nullable"
    }

    Verify {
        uniqueidentifier UserVerificationID PK
        uniqueidentifier UserAccountID "FK, UK"
        datetime VerificationDateTime
    }

    Profile {
        uniqueidentifier UserProfileID PK
        uniqueidentifier UserAccountID "FK, UK"
        nvarchar Biography
    }

    Avatar {
        uniqueidentifier UserAvatarID PK
        uniqueidentifier UserProfileID FK
        uniqueidentifier PhotoID FK
        datetime2 ValidFrom
        datetime2 ValidTo "nullable; at most one row per UserProfileID has ValidTo IS NULL (active avatar)"
    }

    Follow {
        uniqueidentifier UserFollowID PK
        uniqueidentifier UserAccountID FK
        uniqueidentifier FollowingID FK
        datetime CreatedAt
    }

    Photo {
        uniqueidentifier PhotoID PK
        nvarchar Hyperlink "nullable"
        uniqueidentifier UploadedByID FK
        datetime UploadedAt
    }

    Country {
        uniqueidentifier CountryID PK
        nvarchar CountryName
        char ISO3166_1 UK
    }

    StateProvince {
        uniqueidentifier StateProvinceID PK
        nvarchar StateProvinceName
        char ISO3166_2 UK
        uniqueidentifier CountryID FK
    }

    City {
        uniqueidentifier CityID PK
        nvarchar CityName
        uniqueidentifier StateProvinceID FK
    }

    Brewery {
        uniqueidentifier BreweryPostID PK
        nvarchar BreweryName
        uniqueidentifier PostedByID FK
        nvarchar Description
        datetime CreatedAt
        datetime UpdatedAt "nullable"
    }

    BreweryLoc {
        uniqueidentifier BreweryPostLocationID PK
        uniqueidentifier BreweryPostID "FK, UK"
        nvarchar AddressLine1
        nvarchar AddressLine2 "nullable"
        nvarchar PostalCode
        uniqueidentifier CityID FK
        geography Coordinates "nullable"
    }

    BreweryPhoto {
        uniqueidentifier BreweryPostPhotoID PK
        uniqueidentifier BreweryPostID FK
        uniqueidentifier PhotoID FK
        datetime LinkedAt
    }

    BeerStyle {
        uniqueidentifier BeerStyleID PK
        nvarchar StyleName UK
        nvarchar Description "nullable"
    }

    Beer {
        uniqueidentifier BeerPostID PK
        nvarchar Name
        nvarchar Description
        decimal ABV
        int IBU
        uniqueidentifier PostedByID FK
        uniqueidentifier BeerStyleID FK
        uniqueidentifier BrewedByID FK
        datetime CreatedAt
        datetime UpdatedAt "nullable"
    }

    BeerPhoto {
        uniqueidentifier BeerPostPhotoID PK
        uniqueidentifier BeerPostID FK
        uniqueidentifier PhotoID FK
        datetime LinkedAt
    }

    BeerComment {
        uniqueidentifier BeerPostCommentID PK
        nvarchar Comment
        uniqueidentifier BeerPostID FK
        uniqueidentifier CommentedByID FK
        int Rating
        datetime CreatedAt
        datetime UpdatedAt "nullable"
    }