PRO*C에서 EMBEDDED SQL STATEMENTS를 사용해서 LOB DATATYPES에 접근하는 예제

Question

제품 : PRECOMPILERS
작성날짜 : 2001-07-12
PRO*C에서 EMBEDDED SQL STATEMENTS를 사용해서 LOB DATATYPES에 접근하는 예제
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Pro*C에서 LOB를 사용하는 방법에는 다음 3가지가 있습니다.
(1) PL/SQL blocks에서 DBMS_LOB package를 이용하는 방법
(2) OCI function을 이용하는 방법
(3) Embedded SQL statements을 이용하는 방법
다음은 (3)번째 방법에 대한 pro*c에서 지원하는 명령어들입니다.
o APPEND: Appends lob value at the end of another LOB.
EXEC SQL LOB APPEND :src TO :dst;
o ASSIGN: Assigns LOB or BFILE locator to another.
EXEC SQL LOB ASSIGN :src TO :dst;
o CLOSE: Close LOB or BFILE.
EXEC SQL LOB CLOSE :src;
o COPY: Copy all or part of LOB value into another LOB.
EXEC SQL LOB COPY :amt FROM :src [AT :src_offset] TO :dst [AT dst_offset];
o CREATE TEMPORARY: Creates a temporary LOB.
EXEC SQL LOB CREATE TEMPORARY :src;
o ERASE: Erase the given amount of LOB data starting from a given offset.
EXEC SQL LOB ERASE :amt FROM :src [AT :src_offset];
o FILE CLOSE ALL: Closes all the BFILES open in the current session.
EXEC SQL LOB FILE CLOSE ALL;
o FILE SET: Set DIRECTORY alias and FILENAME in a BFILE locator.
EXEC SQL LOB FILE SET :file DIRECTORY = :alias, FILENAME = :filename;
o FREE TEMPORARY: Free the temporary space for the LOB locator.
EXEC SQL LOB FREE TEMPORARY :src
o LOAD FROM FILE: Copy all or part of BFIL into an internal LOB.
EXEC SQL LOB LOAD :amt FROM FILE :file [AT :src_offset]
INTO :dst [AT :dst_offset];
o OPEN: Open a LOB or BFILE for read or read/write.
EXEC SQL LOB OPEN :src [ READ ONLY | READ WRITE ];
o READ: Reads all or part of LOB or BFILE into a buffer.
EXEC SQL LOB READ :amt FROM :src [AT :src_offset]
INTO :buffer [WITH LENGTH :buffer];
o TRIM: Truncates the LOB vlaue.
EXEC SQL LOB TRIM :src to :newlen;
o WRITE: Writes contents of the buffer to a LOB.
EXEC SQL LOB WRITE [APPEND] [FIRST | NEXT | LAST | ONE ]
:amt FROM :buffer [WITH LENGTH :buflen] INTO :dst [AT :dst_offset];
o DESCRIBE: Retrieves the attributes from a LOB.
EXEC SQL LOB DESCRIBE :src GET attribute1 [{, attributeN}]
INTO :hv1 [[INDICATOR] :hv_ind1] [{, :hvN [[INDICATOR] :hv_indN] }];
Attributes can be any of the following:
CHUNKSIZE: chunk size used to store the LOB value
DIRECTORY: name of the DIRECTORY alias for BFILE
FILEEXISTS: whether BFILE exists or not
FILENAME: BFILE name
ISOPEN: whether BFILE with this locate is OPEN or not
ISTEMPORARY: whether specified LOB is temporary or not
LENGTH: Length of BLOBs and BFILE in bytes, CLOBs and NCLOBs
in characters.
다음은 LOB를 사용하는 sample을 실행하는 방법입니다.
1. 먼저 scott user에서 다음을 실행합니다. (create directory를 할 수 있는 권한이
있어야 하며, directory는 사용하시는 환경에 맞도록 수정해 주십시요.)
drop table lob_table;
create table lob_table (key number, a_blob BLOB, a_clob CLOB);
drop table lobdemo;
create table lobdemo (key number, a_blob BLOB, a_bfile BFILE);
drop directory dir_alias;
create directory dir_alias as '/users/app/oracle/product/8.1.7/precomp/demo/proc';
insert into lob_table values(1, utl_raw.cast_to_raw('1111111111'), 'aaaaaaaa');
commit;
2. 다음 코드는 out.gif 파일을 위에서 지정한 directory에 만들고 lob_table의
내용에 들어있는 BLOB의 내용을 저장하는 sample입니다.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
/* Define constants for VARCHAR lengths. */
#define UNAME_LEN 20
#define PWD_LEN 40
/* Declare variables. No declare section is
needed if MODE=ORACLE. */
VARCHAR username[UNAME_LEN]; /* VARCHAR is an Oracle-supplied struct */
varchar password[PWD_LEN]; /* varchar can be in lower case also. */
/* The following 3 lines avoid inclusion of oci.h during precompilation
oci.h is needed only during compilation to resolve calls generated by
the precompiler
#ifndef ORA_PROC
#include <oci.h>
#endif
#include <sqlca.h>
OCIBlobLocator *blob;
OCIClobLocator *clob;
FILE *fp;
unsigned int amt, offset = 1;
#define MAXBUFLEN 5000
unsigned char buffer[MAXBUFLEN];
EXEC SQL VAR buffer IS RAW(MAXBUFLEN);
/* Declare error handling function. */
void sql_error(msg)
char *msg;
char err_msg[128];
size_t buf_len, msg_len;
EXEC SQL WHENEVER SQLERROR CONTINUE;
printf("\n%s\n", msg);
buf_len = sizeof (err_msg);
sqlglm(err_msg, &buf_len, &msg_len);
printf("%.*s\n", msg_len, err_msg);
EXEC SQL ROLLBACK RELEASE;
exit(EXIT_FAILURE);
void main()
/* Connect to ORACLE--
* Copy the username into the VARCHAR.
strncpy((char *) username.arr, "SCOTT", UNAME_LEN);
/* Set the length component of the VARCHAR. */
username.len =
(unsigned short) strlen((char *) username.arr);
/* Copy the password. */
strncpy((char *) password.arr, "TIGER", PWD_LEN);
password.len =
(unsigned short) strlen((char *) password.arr);
/* Register sql_error() as the error handler. */
EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--\n");
/* Connect to ORACLE. Program will call sql_error()
* if an error occurs when connecting to the default database.
EXEC SQL CONNECT :username IDENTIFIED BY :password;
printf("\nConnected to ORACLE as user: %s\n", username.arr);
/* Allocate the LOB host variables and select the BLOB value */
EXEC SQL ALLOCATE :blob;
EXEC SQL ALLOCATE :clob;
EXEC SQL SELECT a_blob INTO :blob FROM lob_table WHERE key=1;
/* Open external file to which BLOB value should be written */
fp = fopen("out.gif", "w");
EXEC SQL WHENEVER NOT FOUND GOTO end_of_lob;
amt = 5000;
EXEC SQL LOB READ :amt FROM :blob AT :offset INTO :buffer;
fwrite(buffer, MAXBUFLEN, 1, fp);
EXEC SQL WHENEVER NOT FOUND DO break;
/* Use polling method to continue reading the next pieces */
while (TRUE)
EXEC SQL LOB READ :amt FROM :blob INTO :buffer;
fwrite(buffer, MAXBUFLEN, 1, fp);
end_of_lob:
fwrite(buffer, amt, 1, fp);
printf("\nG'day.\n\n\n");
/* Disconnect from ORACLE. */
EXEC SQL ROLLBACK WORK RELEASE;
exit(EXIT_SUCCESS);
3. 다음 코드는 위에서 만든 out.gif file을 lobdemo에 저장하는 sample입니다.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sqlda.h>
#include <sqlcpr.h>
/* Define constants for VARCHAR lengths. */
#define UNAME_LEN 20
#define PWD_LEN 40
/* Declare variables. No declare section is
needed if MODE=ORACLE. */
VARCHAR username[UNAME_LEN]; /* VARCHAR is an Oracle-supplied struct */
varchar password[PWD_LEN]; /* varchar can be in lower case also. */
/* The following 3 lines avoid inclusion of oci.h during precompilation
oci.h is needed only during compilation to resolve call generated by
the precompiler
#ifndef ORA_PROC
#include <oci.h>
#endif
#include <sqlca.h>
OCIBlobLocator *blob;
OCIBFileLocator *bfile;
char *alias = "DIR_ALIAS";
char *filename = "out.gif";
unsigned int amt = 50;
unsigned int filelen;
/* Declare error handling function. */
void sql_error(msg)
char *msg;
char err_msg[128];
size_t buf_len, msg_len;
EXEC SQL WHENEVER SQLERROR CONTINUE;
printf("\n%s\n", msg);
buf_len = sizeof (err_msg);
sqlglm(err_msg, &buf_len, &msg_len);
printf("%.*s\n", msg_len, err_msg);
EXEC SQL ROLLBACK RELEASE;
exit(EXIT_FAILURE);
void main()
/* Connect to ORACLE--
* Copy the username into the VARCHAR.
strncpy((char *) username.arr, "SCOTT", UNAME_LEN);
/* Set the length component of the VARCHAR. */
username.len =
(unsigned short) strlen((char *) username.arr);
/* Copy the password. */
strncpy((char *) password.arr, "TIGER", PWD_LEN);
password.len =
(unsigned short) strlen((char *) password.arr);
/* Register sql_error() as the error handler. */
EXEC SQL WHENEVER SQLERROR DO sql_error("ORACLE error--\n");
/* Connect to ORACLE. Program will call sql_error()
* if an error occurs when connecting to the default database.
EXEC SQL CONNECT :username IDENTIFIED BY :password;
printf("\nConnected to ORACLE as user: %s\n", username.arr);
/* Allocate the LOB locator */
EXEC SQL ALLOCATE :blob;
EXEC SQL ALLOCATE :bfile;
/* Initialize the DIRECTORY alias of the BFILE and FILENAME */
EXEC SQL LOB FILE SET :bfile
DIRECTORY = :alias, FILENAME = :filename;
EXEC SQL INSERT INTO lobdemo values (1, EMPTY_BLOB(), :bfile);
EXEC SQL SELECT a_blob, a_bfile INTO :blob, :bfile FROM lobdemo
WHERE key = 1;
EXEC SQL LOB OPEN :bfile;
/* Get the BFILE length */
EXEC SQL LOB DESCRIBE :bfile
GET LENGTH INTO :filelen;
printf("File length is: %d\n", filelen);
amt = filelen;
/* Read BFILE and write to BLOB */
EXEC SQL LOB LOAD :amt FROM FILE :bfile INTO :blob;
EXEC SQL LOB CLOSE :bfile;
printf("\nG'day.\n\n\n");
/* Disconnect from ORACLE. */
EXEC SQL COMMIT WORK RELEASE;
exit(EXIT_SUCCESS);
4. 다음은 실행한 결과 입니다.
첫번째 sample :
Connected to ORACLE as user: SCOTT
G'day.
두번째 sample :
Connected to ORACLE as user: SCOTT
File length is: 10
G'day.

Answer 1