some example for postgresql embeded-sql

postgresql-embeded-sql.cpp

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

#define True 1

void db_connect()
{
    EXEC SQL CONNECT TO db_test@localhost:5432 USER postgres USING password;
}

void db_test()
{
    EXEC SQL BEGIN DECLARE SECTION;
        char dbname[1024];
    EXEC SQL END DECLARE SECTION;

    EXEC SQL SELECT current_database() INTO :dbname;
    printf("current_database = %s \n", dbname);
}

void db_disconnect()
{
     EXEC SQL DISCONNECT ALL;
     printf("Disconnect Database\n");
}

void ChangeDNO()
{
    EXEC SQL BEGIN DECLARE SECTION;
        int maxage = 0;
        char xh[21], xm[21], sex[4];
        char newxh[21];
    EXEC SQL END DECLARE SECTION;

    printf("Input Maxage: ");
    scanf("%d", &maxage);
    getchar();

   // EXEC SQL SELECT xh,xm INTO :xh, :xm FROM s WHERE xb='男';
    EXEC SQL DECLARE ex CURSOR FOR
       SELECT xh, xm, xb FROM s
       WHERE xb = '男' FOR UPDATE OF xh;

    EXEC SQL OPEN ex;
    while(True)
    {
        EXEC SQL FETCH FROM ex INTO :xh,:xm,:sex;
        //if (SQLCA.SQLSTATE == '02000')
        //     break;

        //if (SQLCA.SQLSTATE!='00000')
        //    break;

        char yn = 'N';
        printf("xh: %s, xm:  %s, sex:  %s\n", xh, xm, sex);

        printf("UPDATE 学号?\n");
        yn = getchar();

        if (yn =='y' || yn == 'Y')
        {
            printf("Input NEW xh: ");
            scanf("%s", newxh);
            getchar();
            EXEC SQL UPDATE s SET xh=:newxh WHERE CURRENT OF ex;
 //           EXEC SQL COMMIT;
        }else{
            break;
        }

 //       EXEC SQL FETCH NEXT FROM ex INTO :xh,:xm,:sex;
    }

        EXEC SQL COMMIT;
}

int main(){
    db_connect();
    db_test();
    ChangeDNO();
    db_disconnect();
}