最近需要完成对Oracle数据库LONG字段类型的操作，网上各种查找都没什么完整的教程可参考，偶然获得了LONG类型字段的全套操作方法，记录下来与大家分享。
系列目录如下（Oracle数据库LONG类型字段的完整C代码操作）：
之一--CREATE TABLE(本文)
之二--单纯INSERT
之三--单纯SELECt
之四--DROP TABLE
之五--分段轮询INSERT
之六--分段轮询SELECT
一、LONG类型简介
| Internal Oracle Database Data Type | Maximum Internal Length | Data Type Code |
| LONG | 2^31 - 1bytes(2gigabytes) | 8 |
| 上表参考于Oracle官网 : https://docs.oracle.com/en/database/oracle/oracle-database/21/lnoci/data-types.html#GUID-92331EBC-12FB-4D5F-BFFD-5149F819266D | ||
觉得在写代码时，要用到两点，一是 LONG的大小，最大可达2GB；二是LONG的类型码为8.（先记在脑中，后面用到的时候再细说）
二、本次目标（创建一个含有LONG字段的表）
创建一个含有LONG字段的表，为后面的INSERT操作、SELECT操作做好准备，表名为CAT_1，共有两个字段。
| 字段序号 | 字段名 | 字段类型 |
| 字段1 | ID | NUMBER |
| 字段2 | CATNAME | LONG |
（更多博文，欢迎来我的博客学习交流have_a_cat的博客_CSDN博客-PHP,Dcat-Admin框架,大厂热门笔试面试领域博主）
三、程序结构及重点说明
四、完整代码
#include
#include
#include
#include
typedef struct cdemol2lctx
{
OCIEnv *envhp;
OCIServer *srvhp;
OCISvcCtx *svchp;
OCIError *errhp;
OCISession *authp;
OCIStmt *stmthp;
} cdemol2lctx;
static text *username = (text *) "c##fang";
static text *password = (text *) "fang";
static void initialize(cdemol2lctx *ctxptr);
static void cleanup(cdemol2lctx *ctxptr);
static void checkerr();
static void sql_stmt_execute();
int main();
int main(argc, argv)
int argc;
char *argv[];
{
cdemol2lctx ctx;
text *cretab_stmt1 = (text *)"CREATE TABLE CAT_1 (ID NUMBER, CATNAME LONG)";
printf("n ######## start DEMO program ############ n");
initialize(&ctx);
printf("nCREATING TABLE CAT_1 ... n");
sql_stmt_execute(&ctx, cretab_stmt1);
cleanup(&ctx);
return 1;
}
void sql_stmt_execute(ctxptr, sql_stmt)
cdemol2lctx *ctxptr;
text *sql_stmt;
{
checkerr(ctxptr->errhp, OCIStmtPrepare(ctxptr->stmthp, ctxptr->errhp,
sql_stmt, (ub4) strlen((char *)sql_stmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT));
checkerr(ctxptr->errhp, OCIStmtExecute(ctxptr->svchp,
ctxptr->stmthp,
ctxptr->errhp, (ub4) 1, (ub4)0,
(OCISnapshot *) NULL, (OCISnapshot *) NULL,
OCI_DEFAULT));
}
void initialize(ctxptr)
cdemol2lctx *ctxptr;
{
if (OCIEnvCreate((OCIEnv **) &ctxptr->envhp,
(ub4)OCI_THREADED|OCI_OBJECT, (dvoid *)0,
(dvoid * (*)(dvoid *, size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t))0,
(void (*)(dvoid *, dvoid *)) 0,
(size_t) 0, (dvoid **) 0 ))
printf("FAILED: OCIEnvCreate()n");
printf("n ######## Connect to server ############# n");
if (OCIHandleAlloc((dvoid *) ctxptr->envhp,
(dvoid **) &ctxptr->errhp,
(ub4) OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
printf("FAILED: OCIHandleAlloc() on ctxptr->errhpn");
if (OCIHandleAlloc((dvoid *) ctxptr->envhp,
(dvoid **) &ctxptr->srvhp,
(ub4) OCI_HTYPE_SERVER, (size_t) 0, (dvoid **) 0))
printf("FAILED: OCIHandleAlloc() on ctxptr->srvhpn");
if (OCIHandleAlloc((dvoid *) ctxptr->envhp,
(dvoid **) &ctxptr->svchp,
(ub4) OCI_HTYPE_SVCCTX, (size_t) 0, (dvoid **) 0))
printf("FAILED: OCIHandleAlloc() on ctxptr->svchpn");
if (OCIHandleAlloc((dvoid *) ctxptr->envhp,
(dvoid **) &ctxptr->authp,
(ub4) OCI_HTYPE_SESSION, (size_t) 0, (dvoid **) 0))
printf("FAILED: OCIHandleAlloc() on ctxptr->authpn");
if (OCIServerAttach(ctxptr->srvhp, ctxptr->errhp,
(text *) "", (sb4) strlen((char *) ""),
(ub4) OCI_DEFAULT))
printf("FAILED: OCIServerAttach()n");
if (OCIAttrSet((dvoid *) ctxptr->svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *) ctxptr->srvhp, (ub4) 0,
(ub4) OCI_ATTR_SERVER, ctxptr->errhp))
printf("FAILED: OCIAttrSet() server attributen");
if (OCIAttrSet((dvoid *) ctxptr->authp, (ub4) OCI_HTYPE_SESSION,
(dvoid *) username, (ub4) strlen((char *) username),
(ub4) OCI_ATTR_USERNAME, ctxptr->errhp))
printf("FAILED: OCIAttrSet() useridn");
if (OCIAttrSet((dvoid *) ctxptr->authp, (ub4) OCI_HTYPE_SESSION,
(dvoid *) password, (ub4) strlen((char *) password),
(ub4) OCI_ATTR_PASSWORD, ctxptr->errhp))
printf("FAILED: OCIAttrSet() passwdn");
printf("Logging on as %s ....n", username);
checkerr(ctxptr->errhp, OCISessionBegin((dvoid *)ctxptr->svchp,
ctxptr->errhp, ctxptr->authp,
(ub4) OCI_CRED_RDBMS,(ub4) OCI_DEFAULT ));
printf("%s logged on.n", username);
if (OCIAttrSet((dvoid *) ctxptr->svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *) ctxptr->authp, (ub4) 0, (ub4) OCI_ATTR_SESSION,
ctxptr->errhp))
printf("FAILED: OCIAttrSet() sessionn");
if (OCIHandleAlloc((dvoid *)ctxptr->envhp, (dvoid **) &ctxptr->stmthp,
(ub4)OCI_HTYPE_STMT, (ConST size_t) 0, (dvoid **) 0))
printf("FAILED: alloc statement handlen");
}
void checkerr(errhp, status)
OCIError *errhp;
sword status;
{
text errbuf[512];
sb4 errcode = 0;
switch (status)
{
case OCI_SUCCESS:
break;
case OCI_SUCCESS_WITH_INFO:
(void) printf("Error - OCI_SUCCESS_WITH_INFOn");
break;
case OCI_NEED_data:
(void) printf("Error - OCI_NEED_DATAn");
break;
case OCI_NO_data:
(void) printf("Error - OCI_NODATAn");
break;
case OCI_ERROR:
(void) OCIErrorGet((dvoid *)errhp, (ub4) 1, (text *) NULL, &errcode,
errbuf, (ub4) sizeof(errbuf), OCI_HTYPE_ERROR);
(void) printf("Error - %.*sn", 512, errbuf);
break;
case OCI_INVALID_HANDLE:
(void) printf("Error - OCI_INVALID_HANDLEn");
break;
case OCI_STILL_EXECUTING:
(void) printf("Error - OCI_STILL_EXECUTEn");
break;
case OCI_CONTINUE:
(void) printf("Error - OCI_CONTINUEn");
break;
default:
break;
}
}
void cleanup(ctxptr)
cdemol2lctx *ctxptr;
{
printf("n ########## clean up ############ n");
if (OCISessionEnd(ctxptr->svchp, ctxptr->errhp,
ctxptr->authp, (ub4) 0))
printf("FAILED: OCISessionEnd()n");
printf("%s Logged off.n", username);
if (OCIServerDetach(ctxptr->srvhp, ctxptr->errhp,
(ub4) OCI_DEFAULT))
printf("FAILED: OCIServerDetach()n");
printf("Detached from server.n");
printf("Freeing handles ...n");
if (ctxptr->stmthp)
OCIHandleFree((dvoid *) ctxptr->stmthp, (ub4) OCI_HTYPE_STMT);
if (ctxptr->errhp)
OCIHandleFree((dvoid *) ctxptr->errhp, (ub4) OCI_HTYPE_ERROR);
if (ctxptr->srvhp)
OCIHandleFree((dvoid *) ctxptr->srvhp, (ub4) OCI_HTYPE_SERVER);
if (ctxptr->svchp)
OCIHandleFree((dvoid *) ctxptr->svchp, (ub4) OCI_HTYPE_SVCCTX);
if (ctxptr->authp)
OCIHandleFree((dvoid *) ctxptr->authp, (ub4) OCI_HTYPE_SESSION);
if (ctxptr->envhp)
OCIHandleFree((dvoid *) ctxptr->envhp, (ub4) OCI_HTYPE_ENV);
}
五、编译及运行
5.1 将long_creat.c放入自己的目录下
5.1 将long_creat.c放入自己的目录下
（更多博文，欢迎来我的博客学习交流have_a_cat的博客_CSDN博客-PHP,Dcat-Admin框架,大厂热门笔试面试领域博主）
5.2 编译
gcc long_creat.c -o long_creat -I $ORACLE_HOME/rdbms/public -L $ORACLE_HOME/lib -l clntsh
5.3 运行
./long_creat
5.4 查看数据库中建表情况
show user;
（确定下当前登录的用户，与代码中填写的用户一致）
show con_name;
（本代码里写的是在CDB下建表，所以确认下当前在CDB下，也可以通过修改代码，改为在PDB下建表）
describe CAT_1;
（显示表结构，可以看到，表CAT_1已经创建成功，表共有两列，与预期目标一致）
六、可下载的代码包（懒人福音）
可通过下面的链接，免费下载有猫彬为你准备的代码包（已编译好，可直接运行，内含编译运行命令，直接复制粘贴即可）
https://download.csdn.net/download/have_a_cat/75366720https://download.csdn.net/download/have_a_cat/75366720
（更多博文，欢迎来我的博客学习交流have_a_cat的博客_CSDN博客-PHP,Dcat-Admin框架,大厂热门笔试面试领域博主）
