如何使用 ActiveRecord 调用带有 OUT 参数的 DB2 存储过程？答案

【问题标题】：How can I call a DB2 Stored Procedure with OUT params using ActiveRecord?如何使用 ActiveRecord 调用带有 OUT 参数的 DB2 存储过程？
【发布时间】：2015-11-12 21:02:23
【问题描述】：

我需要使用 ActiveRecord 调用一些遗留存储过程。

当程序没有参数或只有 IN 参数时，我可以使用 ActiveRecords 调用它们。

例如

ActiveRecord::Base.connection.execute('call legacy_proc')

或

ActiveRecord::Base.connection.execute("call legacy_proc('param1', 'param2')")

上面的工作非常好。现在，当我需要使用 OUT 参数调用过程时，问题就出现了。我尝试了不同的调用 SP 的方法，但我无法让它工作。

 ActiveRecord::Base.connection.execute("call legacy_proc_with_out_params('param1', 'param2', ?, ?)")

 ActiveRecord::Base.connection.execute("call legacy_proc_with_out_params('param1', 'param2', null, null)")

 ActiveRecord::Base.connection.execute("call legacy_proc_with_out_params('param1', 'param2', '', '')")

以上都不起作用（最后两个参数是 OUT 参数）。作为最后一个选择，如果真的不可能，我什至可以跳过读取 OUT 参数，只要我至少可以执行该过程。

编辑：添加错误详细信息以澄清“不工作”。

 ActiveRecord::StatementInvalid: ActiveRecord::JDBCError: com.ibm.db2.jcc.am.SqlException: DB2 SQL Error: SQLCODE=-313, SQLSTATE=07004, SQLERRMC=null, DRIVER=4.15.113: call legacy_proc_with_out_params('param1', 'param2', ?, ?)
    from arjdbc/jdbc/RubyJdbcConnection.java:547:in `execute'
    from /home/devusr.gem/gems/activerecord-jdbc-adapter-1.3.16/lib/arjdbc/jdbc/adapter.rb:581:in `_execute'
    from /home/devusr.gem/gems/activerecord-jdbc-adapter-1.3.16/lib/arjdbc/jdbc/adapter.rb:557:in `execute'
    from /home/devusr.gem/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in `log'
    from /home/devusr.gem/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    from /home/devusr.gem/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in `log'
    from /home/devusr.gem/gems/activerecord-jdbc-adapter-1.3.16/lib/arjdbc/jdbc/adapter.rb:557:in `execute'
    from (irb):30:in `evaluate'
    from org/jruby/RubyKernel.java:1119:in `eval'
    from org/jruby/RubyKernel.java:1519:in `loop'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from /home/devusr.gem/gems/railties-4.1.8/lib/rails/commands/console.rb:90:in `start'
    from /home/devusr.gem/gems/railties-4.1.8/lib/rails/commands/console.rb:9:in `start'
    from /home/devusr.gem/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:69:in `console'
    from /home/devusr.gem/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
    from /home/devusr.gem/gems/railties-4.1.8/lib/rails/commands.rb:17:in `(root)'
    from org/jruby/RubyKernel.java:1083:in `require'

编辑 2：尝试了 @mustaccio 的建议（即通过 raw_connection 使用 prepare 方法，但 DB2 适配器没有实现该方法。如果在 DB2 中有实现类似方法的替代路径，这将绝对解决问题。

我也忘了提到我正在使用 jRuby。因此，我使用 DB2 的 jdbc 适配器。

 irb(main):049:0> ActiveRecord::ConnectionAdapters.constants.grep /DB2/
 => [:DB2Column, :DB2JdbcConnection]

 irb(main):050:0> ActiveRecord::Base.connection.raw_connection.methods.sort.grep /prep/
 => []

 irb(main):051:0>  ActiveRecord::Base.connection.raw_connection.prepare
 NoMethodError: undefined method `prepare' for #<ActiveRecord::ConnectionAdapters::DB2JdbcConnection:0xe6bc1cd0>
    from (irb):51:in `evaluate'
    from org/jruby/RubyKernel.java:1119:in `eval'
    from org/jruby/RubyKernel.java:1519:in `loop'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from /home/srpec/.gem/gems/railties-4.1.8/lib/rails/commands/console.rb:90:in `start'
    from /home/srpec/.gem/gems/railties-4.1.8/lib/rails/commands/console.rb:9:in `start'
    from /home/srpec/.gem/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:69:in `console'
    from /home/srpec/.gem/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
    from /home/srpec/.gem/gems/railties-4.1.8/lib/rails/commands.rb:17:in `(root)'
    from org/jruby/RubyKernel.java:1083:in `require'
    from bin/rails:4:in `(root)'

【问题讨论】：

定义“不工作”。
@mustaccio 错误详情添加

标签： ruby stored-procedures activerecord db2 jruby

【解决方案1】：

我找到的解决方案是使用 BEGIN-END 块并声明虚拟变量以绑定到 OUT 参数。

举个例子：

ActiveRecord::Base.connection.execute("call legacy_proc_with_out_params('param1', 'param2', ?, ?)")

第一个 OUT 参数是 INTEGER，第二个是 SMALLINT，完整的调用如下所示：

 beginend_stmt = "BEGIN
                      DECLARE out_Param1 INTEGER;
                      DECLARE out_Param2 SMALLINT;

                      call legacy_proc_with_out_params('param1', 'param2', out_Param1, out_Param2);
                  END"

  ActiveRecord::Base.connection.execute beginend_stmt

【讨论】：