函数PARSENAME使用和截取字符串

DECLARE @str  NVARCHAR(MAX) = N‘testdb.dbo.table_part.qty‘

SELECT 
PARSENAME(@str,4) AS [TABLE_CATALOG],
PARSENAME(@str,3) AS [TABLE_SCHEMA],
PARSENAME(@str,2) AS [TABLE_NAME],
PARSENAME(@str,1) AS [COLUMN_NAME]
GO

;WITH cte_ips AS
(
    SELECT [IPv4],[dbo].[svf_ConvertToStandardIPv4]([IPv4]) AS [std_ip] FROM @ips
)
SELECT [IPv4],[std_ip] FROM cte_ips
ORDER BY PARSENAME([std_ip],4),
         PARSENAME([std_ip],3),
         PARSENAME([std_ip],2),
         PARSENAME([std_ip],1)