functions/Test-DbaDbCompatibility.ps1

function Test-DbaDbCompatibility {
<#
    .SYNOPSIS
        Compares Database Compatibility level to Server Compatibility
         
    .DESCRIPTION
        Compares Database Compatibility level to Server Compatibility
         
    .PARAMETER SqlInstance
        The SQL Server that you're connecting to.
         
    .PARAMETER Credential
        Login to the target instance using alternative credentials. Windows and SQL Authentication supported. Accepts credential objects (Get-Credential)
         
    .PARAMETER Database
        Specifies the database(s) to process. Options for this list are auto-populated from the server. If unspecified, all databases will be processed.
         
    .PARAMETER ExcludeDatabase
        Specifies the database(s) to exclude from processing. Options for this list are auto-populated from the server.
         
    .PARAMETER Detailed
        Will be deprecated in 1.0.0 release.
         
    .PARAMETER EnableException
        By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
        This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
        Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
         
    .NOTES
        Tags: Database, Compatibility
        Author: Chrissy LeMaire (@cl), netnerds.net
        Website: https://dbatools.io
        Copyright: (c) 2018 by dbatools, licensed under MIT
        License: MIT https://opensource.org/licenses/MIT
         
    .LINK
        https://dbatools.io/Test-DbaDbCompatibility
         
    .EXAMPLE
        Test-DbaDbCompatibility -SqlInstance sqlserver2014a
         
        Returns server name, database name and true/false if the compatibility level match for all databases on sqlserver2014a.
         
    .EXAMPLE
        Test-DbaDbCompatibility -SqlInstance sqlserver2014a -Database db1, db2
         
        Returns detailed information for database and server compatibility level for the db1 and db2 databases on sqlserver2014a.
         
    .EXAMPLE
        Test-DbaDbCompatibility -SqlInstance sqlserver2014a, sql2016 -Exclude db1
         
        Returns detailed information for database and server compatibility level for all databases except db1 on sqlserver2014a and sql2016.
         
    .EXAMPLE
        Get-DbaCmsRegServer -SqlInstance sql2014 | Test-DbaDbCompatibility
         
        Returns db/server compatibility information for every database on every server listed in the Central Management Server on sql2016.
         
#>

    [CmdletBinding()]
    [OutputType("System.Collections.ArrayList")]
    param (
        [parameter(Mandatory, ValueFromPipeline)]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstanceParameter[]]$SqlInstance,
        [PSCredential]$Credential,
        [Alias("Databases")]
        [object[]]$Database,
        [object[]]$ExcludeDatabase,
        [switch]$Detailed,
        [Alias('Silent')]
        [switch]$EnableException
    )
    begin {
        Test-DbaDeprecation -DeprecatedOn "1.0.0" -Parameter "Detailed"
    }

    process {
        foreach ($instance in $SqlInstance) {
            Write-Message -Level Verbose -Message "Connecting to $instance."
            try {
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $SqlCredential -MinimumVersion 10
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }

            $serverversion = "Version$($server.VersionMajor)0"
            $dbs = $server.Databases | Where-Object IsAccessible

            if ($Database) {
                $dbs = $dbs | Where-Object { $Database -contains $_.Name }
            }

            if ($ExcludeDatabase) {
                $dbs = $dbs | Where-Object Name -NotIn $ExcludeDatabase
            }

            foreach ($db in $dbs) {
                Write-Message -Level Verbose -Message "Processing $($db.name) on $instance."
                [PSCustomObject]@{
                    ComputerName          = $server.ComputerName
                    InstanceName          = $server.ServiceName
                    SqlInstance           = $server.DomainInstanceName
                    ServerLevel           = $serverversion
                    Database              = $db.name
                    DatabaseCompatibility = $db.CompatibilityLevel
                    IsEqual               = $db.CompatibilityLevel -eq $serverversion
                }
            }
        }
    }
    end {
        Test-DbaDeprecation -DeprecatedOn "1.0.0" -EnableException:$false -Alias Test-DbaDatabaseCompatibility
    }
}