ODBC installation/Use/programming

Objective:

The main explanation of ODBC API, take MySQL as an example, from configuration to installation, and then to specific programming, with a view to ODBC have a preliminary understanding.

*) Download MySQL, select Community Edition MySQL, and install
http://dev.mysql.com/downloads/mysql/

*) Download MYSQL-ODBC driver driver, remember to download version 32
http://dev.mysql.com/downloads/connector/odbc/

*) using the ODBC Data Source Manager, the recommended Odbcad32.exe
Http://support.microsoft.com/kb/942976/zh-cn

*) Drive in the registry
In the registry directory entry Hkey_local_machine\software\odbc\odbcinst. INI, you can see the specifics of MySQL ODBC driver. Catalog Item ODBC drivers holds all ODBC driver information that is already installed on the system. Catalog items MySQL ODBC 5.3 Unicode driver saves specific MySQL driver information.
What is the difference between key driver and key setup? Driver corresponds to the DLL, is the implementation of the ODBC Driver, and the corresponding DLL for the setup, just applies to the System ODBC Driver Manager (Odbc.exe, Odbcad32.exe), used to configure the DNS data source. For a 32-bit driver, its corresponding registry directory entry is Hkey_local_machine\software\wow6432node\odbc\odbcinst. INI, this is also a difference point.

*) in the user/System DSN, add DSN, select Mysql-odbc,:

To edit a DSN:

In the Windows Registry directory entry Hkey_current_user\software\odbc\odbc. INI, the DSN created for the specific.

The data source Mysql_test is previously created, specifically documenting detailed configuration information, where driver specifically corresponds to C:\Program Files (x86) \mysql\connector ODBC 5.3\myodbc5w.dll, Database corresponding to test. Each data source has a different specific item. The ODBC Data Sources catalog entry, which records all other data source items, makes it easy to tell the driver manager the data source type of the specific ODBC drive.

The difference between a user DSN and a System DSN is that the user DSN is valid only for the current user, and the location information for the registry where it resides is generally hkey_current_user\software\odbc\odbc. INI directory entry, and the System DSN is valid for all users in HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC. INI directory entry.

*) under Database test, create a

*) Odbc-api Example
Http://wenku.baidu.com/link?url=Reerd4fWwMOoSLW1gmCQgluaMFEMUBq1Wq-o6e3Iu13UbZaaqKYpwNPnX0Ik_ Rxebvhtng380ghmzbjxfv65k0f3410slf-5wwd3lluwte7
Http://wenku.baidu.com/view/7cefbf1ec5da50e2524d7fbc.html

When the compiler appears with the following error:
Error C2146:syntax error:missing '; ' before identifier ' Sqlhwnd '
Need to include windows.h before containing sql.h, sqlext.h header file
Refer to the following solutions: http://bbs.csdn.net/topics/60260260

Error occurred: cannot convert parameter 2 from ' SQLCHAR * ' to ' Sqlwchar * '
Refer to the following solutions: http://blog.sina.com.cn/s/blog_6d2a0a1a01019k9r.html

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/* *   *   for example: *       odbc example * * *   本例子的目的: 通过odbc编程, 来对odbc的接口有个感性而深入的认识 * * */#include <stdio.h>#include <assert.h>#include <windows.h> #include <sql.h> #include <sqlext.h> int main() {    HENV henv;    // *) 申请环境句柄     SQLRETURN rcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 设置ODBC版本的环境属性     rcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void *)SQL_OV_ODBC3, 0);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 分配连接句柄     SQLHDBC hdbc;     rcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 连接数据源     rcode = SQLConnect(hdbc, (SQLCHAR *)"mysql_test", SQL_NTS,         (SQLCHAR *)"root", SQL_NTS, (SQLCHAR *)"123456", SQL_NTS);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 创建SQL语句句柄     SQLHSTMT stmt;     rcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc,&stmt);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 执行具体的sql     rcode = SQLExecDirect(stmt, (SQLCHAR*)"select * from tb_student", SQL_NTS);     assert(!(rcode != SQL_SUCCESS && rcode != SQL_SUCCESS_WITH_INFO));    // *) 绑定和获取具体的数据项     SQLINTEGER res = SQL_NTS;     SQLCHAR name[128];     SQLINTEGER age;     SQLBindCol(stmt, 2, SQL_C_CHAR, name, sizeof(name), &res);     SQLBindCol(stmt, 3, SQL_C_SLONG, &age, sizeof(age), &res);     while ((rcode=SQLFetch(stmt))!=SQL_NO_DATA_FOUND) {         if( rcode == SQL_ERROR) {             printf("sql error!\n");         } else {             printf("name:%s, age:%ld\n",name, age);         }     }    // *) 清理工作, 释放具体的资源句柄     SQLFreeHandle(SQL_HANDLE_STMT, stmt);     SQLDisconnect(hdbc);     SQLFreeHandle(SQL_HANDLE_DBC, hdbc);     SQLFreeHandle(SQL_HANDLE_ENV, henv);    return 0;}<span style="line-height: 1.5;"> </span>

Data type conversion list with ODBC

C Language Data type name	ODBC data type definition	Actual type of C language
Sql_c_char	SQLCHAR *	unsigned char *
SQL_C_SSHORT[J]	Sqlsmallint	Short int
SQL_C_USHORT[J]	Sqlusmallint	unsigned short int
SQL_C_SLONG[J]	Sqlinteger	Long int
SQL_C_ULONG[J]	Sqluinteger	unsigned long int
Sql_c_float	Sqlreal	Float
Sql_c_double	SqlDouble, Sqlfloat	Double
Sql_c_bit	SQLCHAR	unsigned char
SQL_C_STINYINT[J]	Sqlschar	Signed Char
SQL_C_UTINYINT[J]	SQLCHAR	unsigned char
Sql_c_sbigint	Sqlbigint	_INT64[H]
Sql_c_ubigint	Sqlubigint	unsigned _int64[h]
Sql_c_binary	SQLCHAR *	unsigned char *
Sql_c_bookmark[i]	BOOKMARK	unsigned long int[d]
Sql_c_varbookmark	SQLCHAR *	unsigned char *
SQL_C_TYPE_DATE[C]	Sql_date_struct	struct Tagdate_struct { Sqlsmallint year; Sqlusmallint month; Sqlusmallint Day; } date_struct; A
SQL_C_TYPE_TIME[C]	Sql_time_struct	struct Tagtime_struct { Sqlusmallint hour; Sqlusmallint minute; Sqlusmallint second; } time_struct; A
SQL_C_TYPE_TIMESTAMP[C]	Sql_timestamp_struct	struct Tagtimestamp_struct { Sqlsmallint year; Sqlusmallint month; Sqlusmallint Day; Sqlusmallint hour; Sqlusmallint minute; Sqlusmallint second; Sqluinteger fraction; [b] } timestamp_struct; A
Sql_c_numeric	Sql_numeric_struct	struct Tagsql_numeric_struct { SQLCHAR Precision; Sqlschar scale; SQLCHAR Sign[g]; SQLCHAR Val[sql_max_numeric_len]; [E], [f] } sql_numeric_struct;
Sql_c_guid	SqlGuid	struct Tagsqlguid { DWORD Data1; WORD Data2; WORD Data3; BYTE Data4[8]; } SqlGuid; K