此查詢在postgres中有效，但不在oracle中

Question

SELECT 
    DateTo,(((((DATE_PART('Year',DateTo))-(DATE_PART('Year',DateFrom)))*12)+(DATE_PART('Month',DateTo))-(DATE_PART('Month',DateFrom)))+1) AS NoOfMonth 
FROM HT_LoanSusp 

此查詢在postgres中工作，但不在oracle中。這是由於date_part函數不支持在oracle中。

所以我需要一個可以在oracle和postgres中工作的函數。

Answer 1

使用EXTRACT功能存在於兩個數據庫：

• EXTRACT (datetime) in Oracle
• EXTRACT (field FROM source) in PosgreSQL

然後將查詢：

SELECT 
    DateTo,(((((EXTRACT(YEAR FROM Ht_LoanSusp.DateTo))-(EXTRACT(YEAR FROM Ht_LoanSusp.DateFrom)))*12)+ 
    (EXTRACT(MONTH FROM Ht_LoanSusp.DateTo))-(EXTRACT(MONTH FROM Ht_LoanSusp.DateFrom)))+1) AS NoOfMonth 
FROM HT_LoanSusp