Multiple dynamic values in a Pro *C query IN clause

问题

I want to read a flat file to fetch a dynamic list of values (number of values is not fixed) & then I want to use this list of values in the IN clause of an select query in Pro *C. What is the best way to achieve this using Pro *C? I came across a few useful articles here & here but I just want to check if there is a more suited solution to my use case. It will be also useful to weigh the pros and cons of options that I might have.

Just to give an example, the following is the query:

SELECT ca.co_id
INTO :host_co_id_1
FROM contr1 ch1, contr2 ca
WHERE ch_seqno = (SELECT MAX (ch_seqno) FROM ontr1 ch2
WHERE ch1.co_id = ch2.co_id)
and ch1.ch_status IN ('a','s')
AND ca.co_id = ch1.co_id
AND ca.tmcode IN (14,16,36,37,38,39,40,41,42,79,60);

The number list:

14,16,36,37,38,39,40,41,42,79,60

is the dynamic list read from a file.

回答1:

This is possible using Oracle Dynamic SQL:Method 4. sample10.pc included in the demo illustrates this method.
sample code below
The variable stmt can be read from a file with an IN clause with multiple dynamic values.

 /*
* A very simple program that demonstrates how to do
* array fetches using dynamic SQL Method 4.
* file name: sample.pc
* environment: Win 7,code::blocks(mingw/gcc),oracle 11g(on solaris)
* Make sure to precompile with MODE=ORACLE.
example:
C:\oracle_instant_client\instantclient_11_2\sdk\proc.exe DYNAMIC=ORACLE C:\code\sample.pc
*/

#include <stdio.h> 
#include <stdlib.h>
#include <oci.h>

EXEC SQL INCLUDE sqlcpr;
EXEC SQL INCLUDE sqlda;
EXEC SQL INCLUDE oraca;
EXEC SQL INCLUDE sqlca;

#define MAX_SELECT_ITEMS   15
#define FETCH_SIZE         100  /* Fetch in 100 row chunks. */
#define MAX_CHARS          20   /* Change this for max colume size */
#define MAX_NAME_SIZE      20  /* Maximum size of a select-list item name. */

SQLDA   *selda; 

/* Data buffer. */
char c_data[MAX_SELECT_ITEMS][FETCH_SIZE][MAX_CHARS];

void print_rows(n)
int n;
{
int row, sli;

for (row = 0; row < n; row++)
{
    for (sli = 0; sli < selda->N; sli++)
    {
        printf("%.20s ", c_data[sli][row]);
    }
   printf("\n");
}
}

EXEC SQL BEGIN DECLARE SECTION;
int array_size = FETCH_SIZE;  /* needs to be a host var for FOR */
char *username = "ORACLE_USER/ORACLE_PASS";
char sid[]="ORACLE_SID";
char *stmt = "select t.a,t.b,t.c,p.d,t.e,t.f,t.g,t.h,t.i,t.j from table_t t,table_p p where p.error_code = t.error_code and rownum <= 50";
EXEC SQL END DECLARE SECTION;


void sql_error()
{
char msgbuf[512];/*
size_t msgbuf_len, msg_len;

msgbuf_len = sizeof(msgbuf);
sqlglm(msgbuf, &msgbuf_len, &msg_len);

printf ("\n\n%.*s\n", msg_len, msgbuf);*/

EXEC SQL WHENEVER SQLERROR CONTINUE;
EXEC SQL ROLLBACK WORK RELEASE;
exit(EXIT_FAILURE);
}

void main() 
{ 
int row_count;
int sli;     /* select-list item */

EXEC SQL CONNECT :username USING :sid; 
if (sqlca.sqlcode == 0)
printf("Connected.\n"); 
else
{
printf("Connection failed.\n");
exit(EXIT_FAILURE);
}

EXEC SQL WHENEVER SQLERROR DO sql_error();


selda = SQLSQLDAAlloc (SQL_SINGLE_RCTX, MAX_SELECT_ITEMS, MAX_NAME_SIZE, 0);

EXEC SQL PREPARE S FROM :stmt;
EXEC SQL DECLARE C CURSOR FOR S;
EXEC SQL OPEN C;
EXEC SQL DESCRIBE SELECT LIST FOR S INTO selda;

selda->N = selda->F;   /* Assumed not negative. */
for (sli = 0; sli < selda->N; sli++)
{
    /* Set addresses of heads of the arrays in the V element. */
    selda->V[sli] = c_data[sli][0];
    /* Convert everything to varchar on output. */
    selda->T[sli] = 1;
    /* Set the maximum lengths. */
    selda->L[sli] = MAX_CHARS;
}

for (row_count = 0; ;)
{
    /* Do the fetch. The loop breaks on NOT FOUND. */
    EXEC SQL FOR :array_size FETCH C USING DESCRIPTOR selda;

    print_rows(sqlca.sqlerrd[2] - row_count);
    row_count = sqlca.sqlerrd[2];
    if (sqlca.sqlcode == 1403)
    break;
}

/*    if (sqlca.sqlerrd[2] - row_count > 0)
print_rows(sqlca.sqlerrd[2] - row_count); */

printf("\n%d rows retrieved\n", sqlca.sqlerrd[2]);

EXEC SQL ROLLBACK RELEASE;
exit(EXIT_SUCCESS);
}

来源：https://stackoverflow.com/questions/22917859/multiple-dynamic-values-in-a-pro-c-query-in-clause

标签

oracle-pro-c

embedded-sql