functions/Test-DbaMigrationConstraint.ps1

function Test-DbaMigrationConstraint {
    <#
        .SYNOPSIS
            Show if you can migrate the database(s) between the servers.
 
        .DESCRIPTION
            When you want to migrate from a higher edition to a lower one there are some features that can't be used.
            This function will validate if you have any of this features in use and will report to you.
            The validation will be made ONLY on on SQL Server 2008 or higher using the 'sys.dm_db_persisted_sku_features' dmv.
 
            This function only validate SQL Server 2008 versions or higher.
            The editions supported by this function are:
                - Enterprise
                - Developer
                - Evaluation
                - Standard
                - Express
 
            Take into account the new features introduced on SQL Server 2016 SP1 for all versions. More information at https://blogs.msdn.microsoft.com/sqlreleaseservices/sql-server-2016-service-pack-1-sp1-released/
 
            The -Database parameter is auto-populated for command-line completion.
 
            .PARAMETER Source
                Source SQL Server. You must have sysadmin access and server version must be SQL Server version 2000 or higher.
 
            .PARAMETER SourceSqlCredential
                Allows you to login to servers using SQL Logins instead of Windows Authentication (AKA Integrated or Trusted). To use:
 
                $scred = Get-Credential, then pass $scred object to the -SourceSqlCredential parameter.
 
                Windows Authentication will be used if SourceSqlCredential is not specified. SQL Server does not accept Windows credentials being passed as credentials.
 
                To connect as a different Windows user, run PowerShell as that user.
 
            .PARAMETER Destination
                Destination SQL Server. You must have sysadmin access and the server must be SQL Server 2000 or higher.
 
            .PARAMETER DestinationSqlCredential
                Allows you to login to servers using SQL Logins instead of Windows Authentication (AKA Integrated or Trusted). To use:
 
                $dcred = Get-Credential, then pass this $dcred to the -DestinationSqlCredential parameter.
 
                Windows Authentication will be used if DestinationSqlCredential is not specified. SQL Server does not accept Windows credentials being passed as credentials.
 
                To connect as a different Windows user, run PowerShell as that user.
 
        .PARAMETER Database
            The database(s) to process. Options for this list are auto-populated from the server. If unspecified, all databases will be processed.
 
        .PARAMETER ExcludeDatabase
            The database(s) to exclude. Options for this list are auto-populated from the server.
 
        .NOTES
            Tags: Migration
 
            Author: Claudio Silva (@ClaudioESSilva)
            Website: https://dbatools.io
            Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
            License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
        .LINK
            https://dbatools.io/Test-DbaMigrationConstraint
 
        .EXAMPLE
            Test-DbaMigrationConstraint -Source sqlserver2014a -Destination sqlcluster
 
            All databases on sqlserver2014a will be verified for features in use that can't be supported on sqlcluster.
 
        .EXAMPLE
            Test-DbaMigrationConstraint -Source sqlserver2014a -Destination sqlcluster -SqlCredential $cred
 
            All databases will be verified for features in use that can't be supported on the destination server. SQL credentials are used to authenticate against sqlserver2014 and Windows Authentication is used for sqlcluster.
 
        .EXAMPLE
            Test-DbaMigrationConstraint -Source sqlserver2014a -Destination sqlcluster -Database db1
             
            Only db1 database will be verified for features in use that can't be supported on the destination server.
    #>

    [CmdletBinding(DefaultParameterSetName = "DbMigration")]
    Param (
        [parameter(Mandatory = $true, ValueFromPipeline = $True)]
        [DbaInstanceParameter]$Source,
        [PSCredential]$SourceSqlCredential,
        [parameter(Mandatory = $true)]
        [DbaInstanceParameter]$Destination,
        [PSCredential]$DestinationSqlCredential,
        [Alias("Databases")]
        [object[]]$Database,
        [object[]]$ExcludeDatabase
    )

    begin {
        <#
            1804890536 = Enterprise
            1872460670 = Enterprise Edition: Core-based Licensing
            610778273 = Enterprise Evaluation
            284895786 = Business Intelligence
            -2117995310 = Developer
            -1592396055 = Express
            -133711905= Express with Advanced Services
            -1534726760 = Standard
            1293598313 = Web
            1674378470 = SQL Database
        #>


        $editions = @{
            "Enterprise" = 10;
            "Developer" = 10;
            "Evaluation" = 10;
            "Standard"   = 5;
            "Express" = 1
        }
        $notesCanMigrate = "Database can be migrated."
        $notesCannotMigrate = "Database cannot be migrated."
    }
    process {

        Write-Output "Attempting to connect to Sql Servers."
        $sourceserver = Connect-SqlInstance -SqlInstance $Source -SqlCredential $SourceSqlCredential
        $destserver = Connect-SqlInstance -SqlInstance $Destination -SqlCredential $DestinationSqlCredential

        if ($Database -eq 0) {
            $Database = $sourceserver.Databases | Where-Object isSystemObject -eq 0 | Select-Object Name, Status
        }

        if ($ExcludeDatabase) {
            $Database = $sourceserver.Databases | Where-Object Name -NotIn $ExcludeDatabase
        }

        if ($Database -gt 0) {
            if ($Database -contains "master" -or $Database -contains "msdb" -or $Database -contains "tempdb") {
                throw "Migrating system databases is not currently supported."
            }

            if ($sourceserver.versionMajor -lt 9 -and $destserver.versionMajor -gt 10) {
                throw "Sql Server 2000 databases cannot be migrated to Sql Server versions 2012 and above. Quitting."
            }

            if ($sourceserver.collation -ne $destserver.collation) {
                Write-Warning "Collation on $Source, $($sourceserver.collation) differs from the $Destination, $($destserver.collation)."
            }

            if ($sourceserver.versionMajor -gt $destserver.versionMajor) {
                #indicate that must use 'Generate Scripts' and 'Export Data' options?
                throw "You can't migrate databases from a higher version to a lower one. Quitting."
            }

            if ($sourceserver.versionMajor -lt 10) {
                throw "This function does not support versions lower than SQL Server 2008 (v10)"
            }

            #if editions differs, from higher to lower one, verify the sys.dm_db_persisted_sku_features - only available from SQL 2008 +
            if (($sourceserver.versionMajor -ge 10 -and $destserver.versionMajor -ge 10)) {
                foreach ($db in $Database) {
                    if ([string]::IsNullOrEmpty($db.Status)) {
                        $dbstatus = ($sourceserver.Databases | Where-Object {$_.Name -eq $db}).Status.ToString()
                        $dbName = $db
                    }
                    else {
                        $dbstatus = $db.Status.ToString()
                        $dbName = $db.Name
                    }

                    Write-Verbose "Checking database '$dbName'."

                    if ($dbstatus.Contains("Offline") -eq $false) {
                        [long]$destVersionNumber = $($destserver.VersionString).Replace(".", "")
                        [string]$SourceVersion = "$($sourceServer.Edition) $($sourceServer.ProductLevel) ($($sourceserver.Version))"
                        [string]$DestinationVersion = "$($destserver.Edition) $($destserver.ProductLevel) ($($destserver.Version))"
                        [string]$dbFeatures = ""

                        try {
                            $sql = "SELECT feature_name FROM sys.dm_db_persisted_sku_features"

                            $skufeatures = $sourceServer.Databases[$dbName].ExecuteWithResults($sql)

                            Write-Verbose "Checking features in use..."

                            if ($skufeatures.Tables[0].Rows.Count -gt 0) {
                                foreach ($row in $skufeatures.Tables[0].Rows) {
                                    $dbFeatures += ",$($row["feature_name"])"
                                }

                                $dbFeatures = $dbFeatures.TrimStart(",")
                            }
                        }
                        catch {
                            Write-Warning "Can't execute SQL on $sourceserver. `r`n $($_)"
                            Continue
                        }

                        #If SQL Server 2016 SP1 (13.0.4001.0) or higher
                        if ($destVersionNumber -ge 13040010) {
                            <#
                                Need to verify if Edition = EXPRESS and database uses 'Change Data Capture' (CDC)
                                This means that database cannot be migrated because Express edition don't have SQL Server Agent
                            #>

                            if ($editions.Item($destserver.Edition.ToString().Split(" ")[0]) -eq 1 -and $dbFeatures.Contains("ChangeCapture")) {
                                [pscustomobject]@{
                                    SourceInstance      = $sourceserver.Name
                                    DestinationInstance = $destserver.Name
                                    SourceVersion       = $SourceVersion
                                    DestinationVersion  = $DestinationVersion
                                    Database            = $dbName
                                    FeaturesInUse       = $dbFeatures
                                    Notes               = "$notesCannotMigrate. Destination server edition is EXPRESS which does not support 'ChangeCapture' feature that is in use."
                                }
                            }
                            else {
                                [pscustomobject]@{
                                    SourceInstance      = $sourceserver.Name
                                    DestinationInstance = $destserver.Name
                                    SourceVersion       = $SourceVersion
                                    DestinationVersion  = $DestinationVersion
                                    Database            = $dbName
                                    FeaturesInUse       = $dbFeatures
                                    Notes               = $notesCanMigrate
                                }
                            }
                        }
                        #Version is lower than SQL Server 2016 SP1
                        else {
                            Write-Verbose "Source Server Edition: $($sourceserver.Edition) (Weight: $($editions.Item($sourceserver.Edition.ToString().Split(" ")[0])))"
                            Write-Verbose "Destination Server Edition: $($destserver.Edition) (Weight: $($editions.Item($destserver.Edition.ToString().Split(" ")[0])))"

                            #Check for editions. If destination edition is lower than source edition and exists features in use
                            if (($editions.Item($destserver.Edition.ToString().Split(" ")[0]) -lt $editions.Item($sourceserver.Edition.ToString().Split(" ")[0])) -and (!([string]::IsNullOrEmpty($dbFeatures)))) {
                                [pscustomobject]@{
                                    SourceInstance      = $sourceserver.Name
                                    DestinationInstance = $destserver.Name
                                    SourceVersion       = $SourceVersion
                                    DestinationVersion  = $DestinationVersion
                                    Database            = $dbName
                                    FeaturesInUse       = $dbFeatures
                                    Notes               = "$notesCannotMigrate There are features in use not available on destination instance."
                                }
                            }
                            #
                            else {
                                [pscustomobject]@{
                                    SourceInstance      = $sourceserver.Name
                                    DestinationInstance = $destserver.Name
                                    SourceVersion       = $SourceVersion
                                    DestinationVersion  = $DestinationVersion
                                    Database            = $dbName
                                    FeaturesInUse       = $dbFeatures
                                    Notes               = $notesCanMigrate
                                }
                            }
                        }
                    }
                    else {
                        Write-Warning "Database '$dbName' is offline. Bring database online and re-run the command"
                    }

                }
            }
            else {
                #SQL Server 2005 or under
                Write-Warning "This validation will not be made on versions lower than SQL Server 2008 (v10)."
                Write-Verbose "Source server version: $($sourceserver.versionMajor)."
                Write-Verbose "Destination server version: $($destserver.versionMajor)."
            }
        }
        else {
            Write-Output "There are no databases to validate."
        }
    }
    END {
        $sourceserver.ConnectionContext.Disconnect()
        $destserver.ConnectionContext.Disconnect()
        Test-DbaDeprecation -DeprecatedOn "1.0.0" -EnableException:$false -Alias Test-SqlMigrationConstraint
    }
}