.net的数据库天然支持MSSQLServer，但是并非其他数据库不支持，而是微软基于自身利益需要，在支持、营销上推自己的数据库产品；但是作为平台战略，他并非排斥其他数据库，而是参考java体系提出了一套数据库访问规范，让各个第三方进行开发，提供特定的驱动。 MySQL是免费的数据库，在成本上具有无可替代的优势，但是目前来讲，并没有提供。微软把MySQL当作ODBC数据库，可以按照ODBC.Net规范进行访问，具体参考 而实际上，针对ODBC。Net的需要配置DSN的麻烦，而是出现了一个开源的系统MySQLDriverCS，对MySQL的开发进行了封装，实现了.net环境下对于MySQL数据库系统的访问。 通过阅读源代码，我们看到MySQLDriverCS的思路是利用C函数的底层库来操纵数据库的，通常提供对MySQL数据库的访问的数据库的C DLL是名为libmySQL.dll的驱动文件，MySQLDriverCS作为一个.net库进行封装C风格的驱动。 具体如何进行呢？ 打开工程后，我们看到其中有一个比较特殊的.cs文件CPrototypes.cs： #regionLICENSE /* MySQLDriverCS: An C# driver for MySQL. Copyright (c) 2002 Manuel Lucas Vi馻s Livschitz. This file is part of MySQLDriverCS. MySQLDriverCS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. MySQLDriverCS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with MySQLDriverCS; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #endregion usingSystem; usingSystem.Data; usingSystem.Runtime.InteropServices; namespaceMySQLDriverCS { //[StructLayout(LayoutKind.Sequential)] publicclassMYSQL_FIELD_FACTORY { staticstringversion; publicstaticIMYSQL_FIELD GetInstance() { if(version==null) { version = CPrototypes.GetClientInfo(); } if(version.CompareTo("4.1.2-alpha")>=0) { returnnewMYSQL_FIELD_VERSION_5(); } else returnnewMYSQL_FIELD_VERSION_3(); } } publicinterfaceIMYSQL_FIELD { stringName{get;} uintType{get;} longMax_Length {get;} } ///<summary> ///Field descriptor ///</summary> [StructLayout(LayoutKind.Sequential)]//"3.23.32", 4.0.1-alpha internalclassMYSQL_FIELD_VERSION_3: IMYSQL_FIELD { ///<summary> ///Name of column ///</summary> publicstringname; ///<summary> ///Table of column if column was a field ///</summary> publicstringtable; //public string org_table; /* Org table name if table was an alias */ //public string db; /* Database for table */ ///<summary> ///def ///</summary> publicstringdef; ///<summary> ///length ///</summary> publiclonglength; ///<summary> ///max_length ///</summary> publiclongmax_length; ///<summary> ///Div flags ///</summary> publicuintflags; ///<summary> ///Number of decimals in field ///</summary> publicuintdecimals; ///<summary> ///Type of field. Se mysql_com.h for types ///</summary> publicuinttype; ///<summary> ///Name ///</summary> publicstringName { get{returnname;} } ///<summary> ///Type ///</summary> publicuintType { get{returntype;} } ///<summary> ///Max_Length ///</summary> publiclongMax_Length { get {returnmax_length;} } } ///<summary> ///Field descriptor ///</summary> [StructLayout(LayoutKind.Sequential)] internalclassMYSQL_FIELD_VERSION_5: IMYSQL_FIELD { ///<summary> ///Name of column ///</summary> publicstringname; ///<summary> ///Original column name, if an alias ///</summary> publicstringorg_name; ///<summary> ///Table of column if column was a field ///</summary> publicstringtable; ///<summary> ///Org table name if table was an alias ///</summary> publicstringorg_table; ///<summary> ///Database for table ///</summary> publicstringdb; ///<summary> ///Catalog for table ///</summary> //public string catalog; ///<summary> /// def ///</summary> publicstringdef; ///<summary> ///length ///</summary> publiclonglength; ///<summary> ///max_length ///</summary> publiclongmax_length; ///<summary> ///name_length ///</summary> //public uint name_length; ///<summary> ///org_name_length ///</summary> publicuintorg_name_length; ///<summary> ///table_length ///</summary> publicuinttable_length; ///<summary> ///org_table_length ///</summary> publicuintorg_table_length; ///<summary> ///db_length ///</summary> publicuintdb_length; ///<summary> ///catalog_length ///</summary> publicuintcatalog_length; ///<summary> ///def_length ///</summary> publicuintdef_length; ///<summary> ///Div flags ///</summary> publicuintflags; ///<summary> ///Number of decimals in field ///</summary> publicuintdecimals; ///<summary> ///Character set ///</summary> publicuintcharsetnr; ///<summary> ///Type of field. Se mysql_com.h for types ///</summary> publicuinttype; ///<summary> ///Name ///</summary> publicstringName { get {returnname;} } ///<summary> ///Type ///</summary> publicuintType { get {returntype;} } ///<summary> ///Max_Length ///</summary> publiclongMax_Length { get {returnmax_length;} } } //[StructLayout(LayoutKind.Explicit)] publicenumenum_field_types { FIELD_TYPE_DECIMAL, FIELD_TYPE_TINY, FIELD_TYPE_SHORT, FIELD_TYPE_LONG, FIELD_TYPE_FLOAT, FIELD_TYPE_DOUBLE, FIELD_TYPE_NULL, FIELD_TYPE_TIMESTAMP, FIELD_TYPE_LONGLONG,FIELD_TYPE_INT24, FIELD_TYPE_DATE, FIELD_TYPE_TIME, FIELD_TYPE_DATETIME, FIELD_TYPE_YEAR, FIELD_TYPE_NEWDATE, FIELD_TYPE_ENUM=247, FIELD_TYPE_SET=248, FIELD_TYPE_TINY_BLOB=249, FIELD_TYPE_MEDIUM_BLOB=250, FIELD_TYPE_LONG_BLOB=251, FIELD_TYPE_BLOB=252, FIELD_TYPE_VAR_STRING=253, FIELD_TYPE_STRING=254, FIELD_TYPE_GEOMETRY=255 }; ///<summary> ///C prototypes warpper for mysqllib. ///</summary> internalclassCPrototypes { [ DllImport( "libmySQL.dll", EntryPoint="mysql_init" )] unsafepublicstaticexternvoid* mysql_init(void* must_be_null); [ DllImport( "libmySQL.dll", EntryPoint="mysql_close" )] unsafepublicstaticexternvoidmysql_close(void* handle); // BEGIN ADDITION 2004-07-01 BY Alex Seewald // Enables us to call mysql_option to activate compression and timeout [ DllImport( "libmySQL.dll", EntryPoint="mysql_options" )] unsafepublicstaticexternvoidmysql_options(void* mysql,uintoption,uint*value); // END ADDITION 2004-07-01 By Alex Seewald [ DllImport( "libmySQL.dll", EntryPoint="mysql_real_connect" )] unsafepublicstaticexternvoid* mysql_real_connect(void* mysql,stringhost,stringuser,stringpasswd,stringdb,uintport,stringunix_socket,intclient_flag); [ DllImport( "libmySQL.dll", EntryPoint="mysql_query" )] unsafepublicstaticexternintmysql_query(void*mysql,stringquery); [ DllImport( "libmySQL.dll", EntryPoint="mysql_store_result" )] unsafepublicstaticexternvoid*mysql_store_result(void*mysql); [ DllImport( "libmySQL.dll", EntryPoint="mysql_free_result" )] unsafepublicstaticexternvoidmysql_free_result(void*result); [ DllImport( "libmySQL.dll", EntryPoint="mysql_errno" )] unsafepublicstaticexternuintmysql_errno(void*mysql); [ DllImport( "libmySQL.dll", EntryPoint="mysql_error" )] unsafepublicstaticexternstringmysql_error(void*mysql); [ DllImport( "libmySQL.dll", EntryPoint="mysql_field_count" )] unsafepublicstaticexternuintmysql_field_count(void*mysql); [ DllImport( "libmySQL.dll", EntryPoint="mysql_affected_rows" )] unsafepublicstaticexternulongmysql_affected_rows(void*mysql); [ DllImport( "libmySQL.dll", EntryPoint="mysql_num_fields" )] unsafepublicstaticexternuintmysql_num_fields(void*result); [ DllImport( "libmySQL.dll", EntryPoint="mysql_num_rows" )] unsafepublicstaticexternulongmysql_num_rows(void*result); [ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_field_direct" )] unsafepublicstaticexternIntPtr mysql_fetch_field_direct(void*result,uintfieldnr); ///<returns>Returns a string that represents the client library version</returns> [DllImport("libmySQL.dll",CharSet=System.Runtime.InteropServices.CharSet.Ansi, EntryPoint="mysql_get_client_info", ExactSpelling=true)] publicstaticexternstringGetClientInfo(); [ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_row" )] unsafepublicstaticexternIntPtr mysql_fetch_row(void*result); [ DllImport( "libmySQL.dll", EntryPoint="mysql_select_db" )] unsafepublicstaticexternintmysql_select_db(void*mysql,stringdbname); [ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_lengths" )] unsafepublicstaticexternUInt32 *mysql_fetch_lengths(void*result); } } 基本上是将C风格的基础数据结构进行.net的重新定义，然后通过InteropServices进行访问。 具体如何利用这个库进行操作，可以参考其中的例子。 |
