如何使用 NuoDB 在 Ruby On Rails 中手动执行 SQL 命令
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How do you manually execute SQL commands in Ruby On Rails using NuoDB
提问by Patrick Angodung
I'm trying to manually execute SQL commands so I can access procedures in NuoDB.
我正在尝试手动执行 SQL 命令，以便我可以访问 NuoDB 中的过程。
I'm using Ruby on Rails and I'm using the following command:
我正在使用 Ruby on Rails 并使用以下命令：
ActiveRecord::Base.connection.execute("SQL query")
The "SQL query" could be any SQL command.
“SQL 查询”可以是任何 SQL 命令。
Like for example I have a table called "Feedback" and when I execute the command:
例如，我有一个名为“反馈”的表，当我执行命令时：
ActiveRecord::Base.connection.execute("SELECT `feedbacks`.* FROM `feedbacks`")
This would only return a "true" response instead of sending me all the data requested.
这只会返回“真实”响应，而不是向我发送请求的所有数据。
This is the output on the Rails Console is:
这是 Rails 控制台上的输出：
SQL (0.4ms) SELECT `feedbacks`.* FROM `feedbacks`
=> true
I would like to use this to call stored procedures in NuoDB but upon calling the procedures, this would also return a "true" response.
我想用它来调用 NuoDB 中的存储过程，但是在调用这些过程时，这也会返回“true”响应。
Is there anyway I can execute SQL commands and get the data requested instead of getting a "true" response?
无论如何我可以执行SQL命令并获取请求的数据而不是获得“真实”响应？
回答by Patrick Angodung
The working command I'm using to execute custom SQL statements is:
我用来执行自定义 SQL 语句的工作命令是：
results = ActiveRecord::Base.connection.execute("foo")
with "foo" being the sql statement( i.e. "SELECT * FROM table").
“foo”是 sql 语句（即“SELECT * FROM table”）。
This command will return a set of values as a hash and put them into the results variable.
此命令将返回一组值作为散列并将它们放入结果变量中。
So on my rails application_controller.rb I added this:
所以在我的 rails application_controller.rb 我添加了这个：
def execute_statement(sql)
results = ActiveRecord::Base.connection.execute(sql)
if results.present?
return results
else
return nil
end
end
Using execute_statement will return the records found and if there is none, it will return nil.
使用 execute_statement 将返回找到的记录，如果没有，则返回 nil。
This way I can just call it anywhere on the rails application like for example:
这样我就可以在 rails 应用程序的任何地方调用它，例如：
records = execute_statement("select * from table")
"execute_statement" can also call NuoDB procedures, functions, and also Database Views.
“execute_statement”还可以调用 NuoDB 过程、函数以及数据库视图。
回答by Tim Park
For me, I couldn't get this to return a hash.
对我来说，我无法让它返回哈希值。
results = ActiveRecord::Base.connection.execute(sql)
But using the exec_query method worked.
但是使用 exec_query 方法有效。
results = ActiveRecord::Base.connection.exec_query(sql)
回答by MFredrickson-NuoDB
Reposting the answer from our forum to help others with a similar issue:
重新发布我们论坛的答案以帮助其他人解决类似问题：
@connection = ActiveRecord::Base.connection
result = @connection.exec_query('select tablename from system.tables')
result.each do |row|
puts row
end
回答by Andreas Rayo Kniep
res = ActiveRecord::Base.connection_pool.with_connection { |con| con.exec_query( "SELECT 1;" ) }
The above code is an example for
上面的代码是一个例子
- executing arbitrary SQL on your database-connection
- returning the connection back to the connection pool afterwards
- 在您的数据库连接上执行任意 SQL
- 之后将连接返回到连接池
