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在Windows上的MySQL UDF开发应用

  曾以为Windows版本的MySQL存在不能使用UDF的BUG诸提交了一个bug报告。不过似乎发现是我搞错了,MySQL的技术支持人员给了非常完美的解答,同大家分享一下。下边是原文回复。

  

  用户你好。抱歉,这并不是一个bug。下面我粘贴一个以前为某个客户做的简例,假设你有了VC++,源码分发,并且有一个正常运行的MySQL服务器。

  

  我将创建一个UDF它将一个名字:

  

  注意:例子非常简陋,目的是让你了解该如何处理手头的UDF。

  

  - 打开 mysqld.dsw 工作区。

  

  - 添加新项目到这个工作区

  

  - Project name: my_udf // 项目名称:my_udf

  

  - 选择 Win32 Dynamic-Link Library // Win32动态连接库

  

  - 点击 OK

  

  - 选择 An Empty DLL project // 一个空DLL项目

  

  - 点击 Finish

  

  - 点击 OK

  

  - 添加新文件 my_udf.cpp 到项目中:

  

  #include

  

  #include

  

  #include

  

  extern "C" {

  

  char *my_name(UDF_INIT *initid, UDF_ARGS *args, char *is_null,

  

  char *error);

  

  // 兼容C

  

  }

  

  char *my_name(UDF_INIT *initid, UDF_ARGS *args, char *is_null,

  

  char *error)

  

  {

  

  char * me = "my name";

  

  return me;

  

  // 调用此UDF将返回 my name

  

  }

  

  - 按 Ctrl+N 来创建一个新文件。

  

  - 选择 text 类型

  

  - File name: my_udf.def file://文件名:my_udf.def

  

  - 按照下边的内容编辑文件。

  

  LIBRARY UDF_EXAMPLE

  

  DESCRIPTION 'Example Using UDF with VC++'

  

  VERSION 1.0

  

  EXPORTS

  

  my_name

  

  - 右击my_udf项目并选择Settings

  

  - 点 C/C++ 选项卡

  

  - 选择 General

  

  - 添加宏 HAVE_DLOPE 到预处理器定义

  

  - 选择 Preprocessor

  

  - 添加头文件路径: Additional Include directories

  

  例如: ../include

  

  - 按 F7 去编译成 DLL.

  

  - 复制 my_udf.dll 到环境变量path定义过的目录

  

  比如 \winnt\system32 。

  

  - 打开mysql客户端

  

  C:\mysql-udf\bin>mysql -uroot -p

  

  Enter password:

  

  Welcome to the MySQL monitor. Commands end with ; or \g.

  

  Your MySQL connection id is 2 to server version: 3.23.52-max-nt

  

  Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

  

  mysql> CREATE FUNCTION my_name RETURNS STRING SONAME "my_udf.dll";

  

  Query OK, 0 rows affected (0.08 sec)

  

  mysql> select my_name();

  

  mysql> drop function my_name;

  

  Query OK, 0 rows affected (0.00 sec)

  

  以下是MySQL技术人员的回信原文:

  

  Sorry this isn't a bug.

  

  Below I pasted a sample I did sometime ago for another user:

  

  Ok. Assuming you have VC++ and the source distribution and a server

  

  running,

  

  I will create a UDF that returns a name:

  

  Note: the sample is ugly, but the purpose here is to show you how

  

  to handle the UDF.

  

  - Open the mysqld.dsw workspace.

  

  - Add New project to the workspace

  

  - Project name: my_udf

  

  - Select Win32 Dynamic-Link Library

  

  - Click OK

  

  - Select An Empty DLL project

  

  - Click Finish

  

  - Click OK

  

  - Add a new file called my_udf.cpp to the project:

  

  #include

  

  #include

  

  #include

  

  extern "C" {

  

  char *my_name(UDF_INIT *initid, UDF_ARGS *args, char *is_null,

  

  char *error);

  

  }

  

  char *my_name(UDF_INIT *initid, UDF_ARGS *args, char *is_null,

  

  char *error)

  

  {

  

  char * me = "my name";

  

  return me;

  

  }

  

  - Type Ctrl+N for to create a new file.

  

  - Select text type

  

  - File name: my_udf.def

  

  - Edit the above file with the below contents:

  

  LIBRARY UDF_EXAMPLE

  

  DESCRIPTION 'Example Using UDF with VC++'

  

  VERSION 1.0

  

  EXPORTS

  

  my_name

  

  - Right Click the my_udf project and select Settings

  

  - Click the C/C++ tab

  

  - Select General in the Category Combo

  

  - Add the macro HAVE_DLOPEN to the PreProcessor definition

  

  - Select Preprocessor in the Category Combo

  

  - Add the include path to the text box: Additional Include directories

  

  e.g: ../include

  

  - Press F7 for to build the DLL.

  

  - Copy the my_udf.dll to the environment path directory:

  

  \winnt\system32 for example.

  

  - Start the mysql client and issue:

  

  C:\mysql-udf\bin>mysql -uroot -p

  

  Enter password:

  

  Welcome to the MySQL monitor. Commands end with ; or \g.

  

  Your MySQL connection id is 2 to server version: 3.23.52-max-nt

  

  Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

  

  mysql> CREATE FUNCTION my_name RETURNS STRING SONAME "my_udf.dll";

  

  Query OK, 0 rows affected (0.08 sec)

  

  mysql> select my_name();

  

  mysql> drop function my_name;

  

  Query OK, 0 rows affected (0.00 sec)