C# 帮助构建要查询的 where 子句

Question

我是 C# 新手，

我想构建查询字符串，我做了一些条件，每个条件都向 where 子句添加另一个条件，

我想要类似的东西：

    // BUILD SELECT QUERY
     string where = "";
     string[] where_arr = new string[];
     if (condition1)
     {
           where_arr[index++] = " field = 5 ";
     }
      if (condition2)
     {
           where_arr[index++] = " field2 = 7 ";
     }

     if (where_arr.Count>0)
        where = " where" +  String.Join(" and ", where_arr);
     string sql = "select count(*) as count from mytable " + where;

但我不知道如何声明所有变量，如 where_arr< /代码>

Answer 1

// BUILD SELECT QUERY
string where = "";
List<string> where_arr = new List<string>();

if (condition1)
{
    where_arr.Add(" field = 5 ");
}

if (condition2)
{
    where_arr.Add(" field2 = 7 ");
}

if (where_arr.Count > 0)
    where = " where" + String.Join(" and ", where_arr.ToArray());
string sql = "select count(*) as count from mytable " + where;