如何从 C 程序连接到 IBM Db2 Event Store？答案

【问题标题】：How do I connect to IBM Db2 Event Store from a C program?如何从 C 程序连接到 IBM Db2 Event Store？
【发布时间】：2019-10-07 00:06:22
【问题描述】：

我希望能够从 C 程序连接到 IBM Db2 Event Store 实例。我在文档中看到它支持标准 Db2 JDBC 连接https://www.ibm.com/support/knowledgecenter/SSGNPV_2.0.0/develop/dev-guide.html。它还支持 ODBC 和标准 Db2 CLI 吗？

【问题讨论】：

标签： c db2 ibm-event-store

【解决方案1】：

我找到了下面这个例子https://github.com/IBMProjectEventStore/db2eventstore-IoT-Analytics/tree/master/AdvancedApplications/ODBCApplication

从示例中可以看出它正在使用 SQLDriverConnect API 进行连接，并为它提供了此脚本下载的证书https://github.com/IBMProjectEventStore/db2eventstore-IoT-Analytics/blob/master/container/setup/setup-ssl.sh

/* connect to a database with additional connection parameters
   using SQLDriverConnect() */
int DbDriverConnect(SQLHANDLE henv,
                    SQLHANDLE *hdbc, 
                    char dbAlias[],
                    char user[],
                    char pswd[],
                    char hostip[],
                    char port[],
                    char sslcert[])
{
  SQLRETURN cliRC = SQL_SUCCESS;
  int rc = 0;
  SQLCHAR connStr[255];

  printf("\n-----------------------------------------------------------");
  printf("\nUSE THE CLI FUNCTIONS\n");
  printf("  SQLAllocHandle\n");
  printf("  SQLSetConnectAttr\n");
  printf("  SQLDriverConnect\n");
  printf("TO CONNECT TO EVENTSTORE:\n");

  /* allocate a database connection handle */
  cliRC = SQLAllocHandle(SQL_HANDLE_DBC, henv, hdbc);
  ENV_HANDLE_CHECK(henv, cliRC);

  printf("\n  Connecting to the database %s ...\n", dbAlias);

  /* parse connection string */
  sprintf((char *)connStr,
          "DATABASE=%s; UID=%s; PWD=%s; "
          "Protocol=tcpip; Authentication=GSSPLUGIN; "
          "Security=ssl; SSLServerCertificate=%s; "
          "HOSTNAME=%s; PORT=%s;",
          dbAlias, user, pswd, sslcert, hostip, port);

  /* connect to a data source */
  cliRC = SQLDriverConnect(*hdbc,
                           (SQLHWND)NULL,
                           connStr,
                           SQL_NTS,
                           NULL,
                           0,
                           NULL,
                           SQL_DRIVER_NOPROMPT);
  DBC_HANDLE_CHECK(*hdbc, cliRC);

  printf("  Connected to the database %s.\n", dbAlias);
  return 0;
}

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