我已经声明了一个表变量’@t’，并正确执行了’INSERT-INTO-
SELECT’。当我尝试对表变量进行一些额外的计算以获取每组行编号时，我收到错误，或者直接使用’@t’时出现“必须声明变量”，而使用’@t的别名时出现“无效的对象名”
‘。请指教。

SELECT 
    *,
    (SELECT COUNT(*) FROM "LTV" "COUNTER"
     WHERE 
        "COUNTER"."Collateral_ID" = "LTV"."Collateral_ID"
        AND
        "COUNTER"."m_il_no" = "LTV"."m_il_no"
        AND
        "COUNTER"."Ref_Key" <= "LTV"."Ref_Key"
     GROUP BY "COUNTER"."Collateral_ID", "COUNTER"."m_il_no"
    ) "MIL_IDX"

FROM @t AS LTV