[英]Substitution inside verbatim string literals?
与此相关的问题 。有关如何内C#写长长的SQL查询,该解决方案建议,长的SQL查询应该写成:
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
";
这让我对另一个相关问题感到好奇。 我能以某种方式使用替代吗? 也就是说,如果说表名更改但查询保持不变,我将如何管理? 我是否必须回归使用另一种使用字符串连接构建字符串的方法,还是有更优雅的方法?
为什么不使用string.Format? 在您给出的具体示例中,您可以执行类似的操作
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
";
并调用
string real_query = string.Format(query, tblName1, tblName2);
是的,您可以使用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方法将使用字符串后面的参数顺序替换{x}标识的参数,因此{0}将替换为custtype的值,而{1}将替换为cust的值。
您可以考虑使用LINQ to SQL,如果您还没有。
回答实际问题,你可以像其他人提到的那样使用string.Format
创建查询。 如果要修改现有的字符串,请尝试使用string.Replace
或Regex.Replace
描述这里 。 那是:
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");
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