Set-PublicIpAzSqlFirewallRule.ps1

function Set-PublicIpAzSqlFirewallRule {
    [CmdletBinding()]
    param (
        # Name of the SQL server
        [Parameter(Mandatory)]
        [string]
        $ServerName,

        # Name of the SQL server's resource group
        [Parameter(Mandatory)]
        [string]
        $ResourceGroupName,

        # Name of the fireall rule that will be updated
        [Parameter()]
        [string]
        $RuleName = 'MyCurrentPublicIp'
    )

    Write-Verbose "Getting current public IP"
    $publicIp = Invoke-RestMethod -Method GET -Uri 'https://api.ipify.org'

    Write-Verbose "Removing existing firewall rule"
    $null = Get-AzSqlServerFirewallRule -ServerName $ServerName `
        -ResourceGroupName $ResourceGroupName |
        Where-Object FirewallRuleName -eq $RuleName | 
        Remove-AzSqlServerFirewallRule

    Write-Verbose "Adding current public IP $publicIp to allowed IP range"
    New-AzSqlServerFirewallRule -ServerName $ServerName `
        -ResourceGroupName $ResourceGroupName `
        -FirewallRuleName $RuleName `
        -StartIpAddress $publicIp `
        -EndIpAddress $publicIp

}