Grails sql 查询 [英] Grails sql queries

问题描述

想象一下我有这样的事情:

Imagine I have something like this:

def example = {
   def temp = ConferenceUser.findAllByUser(User.get(session.user))
   [temp: temp]
}

解释我的问题:尽管动态查找器非常易于使用且易于学习，但我必须将我网站的动态查找器替换为 sql 查询，因为这是一项要求.由于我不太了解 SQL，我的主要问题是:

Explaining my problem: Although dynamic finders are very easy to use and fast to learn, I must replace dynamic finders of my website for sql queries because it is a requirement. As I don't understand SQL that much, my main questions are:

a) 我正在使用 SQLS 数据库，驱动程序和数据源配置良好，我的网站现在可以正常工作.如果我想替换 sql 语句的findAllByUser"，我应该这样做:

a) I am using an SQLS database, with the drivers and datasource good configured and my website works as it is right now. If I want to replace the "findAllByUser" for an sql statement, should i do something like this:

def dataSource
...
def db = new Sql(dataSource)
def temp = db.rows("SELECT ... ")

b) 那会起作用吗?我的意思是，如果我使用findAllByUser"，临时对象将是一个列表，我是否需要打开与数据库的连接=?

b) And that will work? I mean, the temp object will be a list as it is if I use "findAllByUser", and do I need to open a connection to the database =?

推荐答案

是的，使用 grails，您可以执行普通的 sql 和 hql 查询.HQL 是休眠查询语言"，允许您编写类似 sql 的语句，但使用域类和属性而不是表名和列名.要进行 hql 查询，请执行类似

yes, with grails you can do both plain sql and hql queries. HQL is 'hibernate query language' and allows you to write sql-like statements, but use your domain classes and properties instead of the table names and column names. To do an hql query, do something like

def UserList = ConferenceUser.executeQuery('from ConferenceUser cu where cu.user = ?', [user]),  

这里有一个参数化查询——executeQuery 看到 ?在 hql 字符串中，并为您替换作为方法的第二个参数的数组中的参数(在本例中为[user]).

what you have here is a parameterized query -- executeQuery sees the ? in the hql string and substitutes the arguments in the array that is the second parameter to the method([user] in this case) for you.

见http://grails.org/doc/latest/ref/Domain%20类/executeQuery.html

你可以看到这个关于如何使用 Grails 进行 sql 查询

and you can see this on how to do sql queries with Grails

用于在 grails 中插入的 Sql 查询

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