Data acquisition from Oracle DBMS using C / C ++ under SuSE Linux

Hi habrachelovek!

Faced the other day with the need to get data from Oracle DBMS using C / C ++ under SuSE Linux

Prior to this, I have repeatedly performed similar things from other languages ​​(Perl, PHP, sh), but never from C.
Of all the available tools that allow you to connect to Oracle, I stopped at the method of precompiling proc, the binary of which is included in the basic configuration of the Oracle client.

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The system on which the riot of colors will occur:
vmotp # cat / etc / SuSE-release
SUSE Linux Enterprise Server 11 (i586)
VERSION = 11
PATCHLEVEL = 0
+
oracle.client VER: 10.2.0.1.0


The database itself is on a different machine. Server version: 9.0.2 (I know that it is old, but it serves exclusively as a historical replica and a simple base for temporary tables)

First, let's make an example of the similarity “Hello World”, which will display the result of the query
SELECT 12345,'TEST STRING' FROM dual;

Make a file test_ora.pc with the following content

#include <ctype.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>

#define ORA_PARAM " ORACLE_LOGIN/ORACLE_PASS@ORACLE_SID " /* */

EXEC SQL BEGIN DECLARE SECTION; /* END DECLARE SECTION , Oracle*/
static int ora_i; /* INT */
static VARCHAR ora_str[20]; /* CHAR */
static VARCHAR connect_str[100]; /* */
EXEC SQL END DECLARE SECTION;

EXEC SQL INCLUDE SQLCA; /* SQLCA ( ) */

int main( int argc, char* argv[] )
{
char str[21]; /* CHAR */
memset(str,0,sizeof(str)); /* */
connect_str.len = sprintf(connect_str.arr,ORA_PARAM); /* */
EXEC SQL CONNECT :connect_str; /**/
EXEC SQL WHENEVER SQLERROR CONTINUE;
EXEC SQL SELECT 12345,'TEST STRING' INTO :ora_i,:ora_str FROM dual; /* , */
sprintf( str, "%*.*s", ora_str.len, ora_str.len, ora_str.arr ); /* CHAR C */
printf("\ni=[%d], str=[%s]\n", ora_i, str ); /* */
return 0;
} /* end of main() */


Now you need to “feed” our proc utility file, by default it is located along the path $ ORACLE_HOME / bin /
/opt/oracle/product/11gR1/db/bin/proc CODE=ANSI_C include=/opt/oracle/product/11gR1/db/lib include=/usr/lib/gcc/i586-suse-linux/4.3/include/ ireclen=4800 oreclen=4800 select_error=no release_cursor=no hold_cursor=yes ltype=none cpp_suffix=c USERID= ORACLE_LOGIN/ORACLE_PASS@ORACLE_SID SQLCHECK=SEMANTICS iname=test_ora.pc;


cc test_ora.c -L/opt/oracle/product/11gR1/db/lib /opt/oracle/product/11gR1/db/lib/libclntsh.so /opt/oracle/product/11gR1/db/lib/libsqlplus.a -o test_ora;

Run the resulting file and see that the focus was a success:
vmotp$ ./test_ora

i=[12345], str=[TEST STRING]
vmotp$


Ps. This article is published at the request of my friend. Who does not have a login for Habr, if someone has invites left, please share (lanarion (at) gmail.com).