I'm trying to get a output parameter from MySQL stored procedure, let's have look a example below:
1 In mysql I created this procedure and it works.
CREATE PROCEDURE sp_name (out id int)
Begin
select id into @id from table order by id desc limit 1;
End
mysql> call sp_deduct_credit_and_money(@id);
Query OK, 0 rows affected (0.01 sec)
mysql> select @id;
+--------------+
| @id |
+--------------+
| 24 |
+--------------+
1 row in set (0.00 sec)
2 Therefore, it also works in Rails, BUT it won't return any value for me:
ActiveRecord::Base.connection.execute("call sp_name(@id)")
ActiveRecord::Base.connection.execute("select @id")
Here is the log in Rails
(2.0ms) call sp_name(@id)
(0.1ms) select @id
My question is that how could I get the return value of the output parameter @id
?
I found a way to get the output parameter, to share with you guys, see below:
1 to create a connection
client = Mysql2::Client.new(ActiveRecord::Base.configurations[Rails.env.to_s].symbolize_keys)
2 use this connection to call your sp
client.query "call sp_xxx"
3 to get the output parameter
result = client.query("select @output_parameter")
4 return the output
return !result.first["@output_parameter"].nil?
MySQL doesnt work like SQL Server. If you want a store procedure with a return value, that you really want it's a function (UDF). You need specify the RETURN like any C++ function. Also you dont need use call, because its a function. Just use SELECT function()
Try to look up info about UDF in MySQL manual. There is very explicity help for do that.
来源:https://stackoverflow.com/questions/7480579/how-to-get-output-parameters-from-mysql-stored-procedure-in-rails