逐字字符串文字中的替換？ 。

Question

與此question如何內C＃寫長長的SQL查詢的關係，解決方案建議，長的SQL查詢應該寫成：

string query = @" 
    SELECT 
     c.CUSTOMER_ID, 
     COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME 
     ct.NAME as CUSTOMER_TYPE 
    FROM 
     CT_CUSTOMER_TYPE AS ct INNER JOIN CUSTOMER AS c 
      ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID 
    "; 

這讓我好奇的另一個相關的問題。我能以某種方式使用替代嗎？也就是說，如果說表名更改但查詢保持不變，我將如何管理？我是否必須回到使用字符串連接構建字符串的其他方法，還是有更優雅的方式？

Answer 1

爲什麼不使用string.Format？在你給具體的例子，你可以不喜歡

string query = @" 
SELECT 
    c.CUSTOMER_ID, 
    COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME 
    ct.NAME as CUSTOMER_TYPE 
FROM 
    {0} AS ct INNER JOIN {1} AS c 
     ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID 
"; 

而且調用

string real_query = string.Format(query, tblName1, tblName2); 

Answer 2

是的，你可以使用String.Format方法。

string custtype = "CT_CUSTOMER_TYPE"; 
string cust = "CUSTOMER"; 
string query = @" 
SELECT 
    c.CUSTOMER_ID, 
    COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME 
    ct.NAME as CUSTOMER_TYPE 
FROM 
    {0} AS ct INNER JOIN {1} AS c 
     ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID 
"; 

string endQuery = String.Format(query, custtype, cust); 

String.Format方法將取代通過{X}用字符串以下的參數順序地識別的參數，所以{0}將與custtype的值來代替，和{1}使用的值卡斯特。

Answer 3

如果您還沒有，可以考慮使用LINQ to SQL。

回答實際問題時，如果您正在創建查詢，則可以使用string.Format，正如其他人提到的一樣。如果您希望修改現有的字符串，請嘗試使用string.Replace或Regex.Replace，如here所述。那就是：

string query = @" 
    SELECT 
     c.CUSTOMER_ID, 
     COALESCE (c.FIRST_NAME, ''_ + ' ' + COALESCE (c.LAST_NAME, '') AS FULL_NAME 
     ct.NAME as CUSTOMER_TYPE 
    FROM 
     CT_CUSTOMER_TYPE AS ct INNER JOIN CUSTOMER AS c 
      ON ct.CUSTOMER_TYPE_ID = c.CUSTOMER_TYPE_ID 
    "; 
query.Replace("CT_CUSTOMER_TYPE", "NEW_TABLE_NAME");