SQL select AS - 预置文本

Question

是否可以将文本预加到SQL select语句中。例如： -

var query = "SELECT id, " + 
        "picture " 
      "FROM people"; 

到

var query = "SELECT id, " + 
        "picture AS './directory/' + picture " 
      "FROM people"; 

Answer 1

是。事情是这样的：

var query = "SELECT id, " + 
       "concat('./directory/',picture) AS picture " 
       "FROM people"; 

位的详细信息：http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_concat

Answer 2

您正在构建的查询作为一个字符串，那么是的，你可以做到这一点。但是，您必须将该值作为常量插入。喜欢的东西：

var query = "SELECT id, " + 
        "picture AS " + directory " + "picture " 
      "FROM people"; 

然而，directory将需要在应用程序和值不是数据库（虽然另一份声明中可以读它）。