Azure自动化Powersell Runbook失败：'Invoke-Sqlcmd'无法识别为cmdlet的名称

Question

我已经完成了以下教程的所有步骤，以获得用于自动化索引和统计维护的Runbook：

https://blogs.msdn.microsoft.com/azuresqldbsupport/2018/01/15/automating-azure-sql-db-index-and-statistic-maintenance-using-azure-automation/

我能够毫无错误地完成所有教程，但是当我执行Runbook时，它返回一个错误：

Invoke-Sqlcmd : The term 'Invoke-Sqlcmd' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:6 char:16
+ $SQLOutput = $(Invoke-Sqlcmd -ServerInstance $AzureSQLServerName -Use ...
+ ~~~~~~~~~~~~~
+ CategoryInfo: ObjectNotFound: (Invoke-Sqlcmd:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException

我该怎么办？我在Azure中使用SQL Server。具体而言，Azure SQL数据库具有定价/模型层“S4标准（200 DTU）”。