看过了dcba的ociUldr的程序，非常有感触,七八年没编程了，忽然间有了写写程序的冲动，顺便也学学oci的编程。学习编程最好的方法是看demo。如下分享给大家一个demo,供入门用。

1 demo要实现的功能

以hr/hr用库连入orcl库，执行select first_name from employees where employee_id=102语句，并返回结果。其中oci编程的基本部分都有涉及。

2 demo脚本

#include
#include
#include
#include

static OCIEnv           *p_env;
static OCIError         *p_err;
static OCISvcCtx        *p_svc;
static OCIStmt          *p_sql;
static OCIDefine        *p_dfn    = (OCIDefine *) 0;
static OCIBind          *p_bnd    = (OCIBind *) 0;

int main()
{
   int             p_bvi;
   char            *p_sli;
   int             rc;
   char            errbuf[100];
   int             errcode;
   char            mysql[100];
  
   p_sli=(char *)malloc(20);
   memset(p_sli,0,20);
  
   /* Initialize OCI evironment*/
   rc = OCIEnvCreate((OCIEnv **) &p_env,OCI_DEFAULT,(dvoid *)0,
          (dvoid * (*)(dvoid *, size_t)) 0,
          (dvoid * (*)(dvoid *, dvoid *, size_t))0,
          (void (*)(dvoid *, dvoid *)) 0,      
          (size_t) 0, (dvoid **) 0);
  
   /* Initialize handles */
   rc = OCIHandleAlloc( (dvoid *) p_env, (dvoid **) &p_err, OCI_HTYPE_ERROR,
           (size_t) 0, (dvoid **) 0);
   rc = OCIHandleAlloc( (dvoid *) p_env, (dvoid **) &p_svc, OCI_HTYPE_SVCCTX,
           (size_t) 0, (dvoid **) 0);

   /* Connect to database server */
   rc = OCILogon(p_env, p_err, &p_svc, "hr", 2, "hr", 2, "orcl", 4);
   //rc = OCILogon(p_env, p_err, &p_svc, "hr/hr@orcl", 10, NULL, -1, NULL, -1);
   if (rc != 0) {
      OCIErrorGet((dvoid *)p_err, (ub4) 1, (text *) NULL, &errcode, errbuf, (ub4) sizeof(errbuf), OCI_HTYPE_ERROR);
      printf("Error - %.*s\n", 512, errbuf);
      exit(8);
   }
   else
   {
    printf("Connect to orcl successful!\n"); 
   }

   /* Allocate and prepare SQL statement */
   rc = OCIHandleAlloc((dvoid *) p_env, (dvoid **) &p_sql,
           OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0);

   /* set my sql statement */
   strcpy(mysql,"select first_name from employees where employee_id=:x");
   rc = OCIStmtPrepare(p_sql, p_err, mysql,
           (ub4) strlen(mysql), (ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT);

   /* Bind the values for the bind variables */
   p_bvi = 102;  /* Use employee_id=102 */
   rc = OCIBindByName(p_sql, &p_bnd, p_err, (text *) ":x",
           -1, (dvoid *) &p_bvi, sizeof(int), SQLT_INT, (dvoid *) 0,
           (ub2 *) 0, (ub2 *) 0, (ub4) 0, (ub4 *) 0, OCI_DEFAULT);

   /* Define the select list items */
   rc = OCIDefineByPos(p_sql, &p_dfn, p_err, 1, (dvoid *) p_sli,
           (sword) 20, SQLT_STR, (dvoid *) 0, (ub2 *)0,
           (ub2 *)0, OCI_DEFAULT);

   /* Execute the SQL statment */
   rc = OCIStmtExecute(p_svc, p_sql, p_err, (ub4) 1, (ub4) 0,
           (CONST OCISnapshot *) NULL, (OCISnapshot *) NULL, OCI_DEFAULT);
 

  while (rc != OCI_NO_DATA) {             /* Fetch the remaining data */
      printf("%s\n",p_sli);
      rc = OCIStmtFetch(p_sql, p_err, 1, 0, 0);
  }

   rc = OCILogoff(p_svc, p_err);                           /* Disconnect */
   rc = OCIHandleFree((dvoid *) p_sql, OCI_HTYPE_STMT);    /* Free handles */
   rc = OCIHandleFree((dvoid *) p_svc, OCI_HTYPE_SVCCTX);
   rc = OCIHandleFree((dvoid *) p_err, OCI_HTYPE_ERROR);

   return;
}

3 编译命令

gcc -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I${ORACLE_HOME}/rdbms/public -I${ORACLE_HOME}/rdbms/demo -L${ORACLE_HOME}/lib -lclntsh -o hh1 hh1.c

4 编译并执行

hpn2$./hh1
Connect to orcl successful!
Lex