SQL选择AS - 前置文本

Question

是否可以将文本添加到SQL select语句中。 e.g：

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

到

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

Answer 1

是。像这样：

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

更多细节：http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_concat

Answer 2

您正在将查询构造为字符串，所以是的，您可以这样做。但是，您必须将值作为常量插入。类似的东西：

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

但是，directory需要是应用程序中的值而不是数据库（尽管另一个语句可以读取它）。