C language embedded in Informix Basic introductory example to explain _c language

Copy Code code as follows:

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

$struct _db_person
{
Char name[30+1];
Char card[12+1];
int age;
};

Char *trim (char *str)
{
Char *p, *buffer;
int Len;

if (NULL!=STR)
{
len = strlen (str);
if (len > 0)
{
Buffer= (char *) malloc (sizeof (char) * (len+1));
if (NULL!= buffer)
{
Memmove (buffer, str, len);
buffer[len]=0;

p = buffer + len-1;
while ((P!= buffer) && ((*p > 0x00) && (*p <= '))
* (p--) = 0;
p = buffer;
while ((*p > 0x00) && (*p <= '))
p++;
strcpy (str, p);
Free (buffer);
}
}
}
return str;

}

int GetData (struct _db_person *pps)
{
Char strage[20];

memset (PPS, 0, sizeof (struct _db_person));
printf ("Enter name<press enter only to Exit>:");
Fgets (Pps->name,sizeof (pps->name), stdin);
Trim (pps->name);
if (strlen (pps->name) = = 0)
return-1;
printf ("Enter card no<press enter only to Exit>:");
Fgets (Pps->card,sizeof (Pps->card), stdin);
Trim (Pps->card);
if (strlen (pps->card) = = 0)
Return-2;
printf ("Enter age<press enter only to Exit>:");
Fgets (Strage,sizeof (strage), stdin);
Trim (strage);
if (strlen (strage) = = 0)
return-3;
Pps->age = Atoi (strage);

return 0;
}

int main (void)
{
$struct _db_person dbps;

$database exec01;
if (SQLCODE!= 0)
{
printf ("Open demo1 failure,sqlcode=%d\n", SQLCODE);
return-1;
}
while (1)
{
if (GetData (&dbps) <0)
Break
$insert into person (name, card, age) VALUES ($dbps. Name, $dbps. Card, $dbps. Age);
printf ("Insert Data result:sqlcode=%d\n", SQLCODE);
$declare vcursor cursor for select name, card, age into $dbps. Name, $dbps.
printf ("Declare vcursor result:sqlcode=%d\n", SQLCODE);
$open Vcursor;
printf ("Open vcursor result:sqlcode=%d\n", SQLCODE);
if (0==sqlcode)
{
while (1)
{
$fetch Vcursor;
if (0==sqlcode)
{
printf ("name=[%s],card=[%s],age=[%d]\n", dbps.name,dbps.card,dbps.age);
}
Else
{
if (sqlcode==100)
printf ("Fetch end!\n");
Else
printf ("Fetch failure! Sqlcode=%d\n ", SQLCODE);
Break
}
}
}
$close Vcursor;
$free Vcursor;
}
$disconnect current;

return 0;
}

The program embeds the Informix database in simple C, the source file is. ec file, the compiler is esql, header file directory: $ (informixdir)/include, admin tool dbaccess, usage: dbaccess [dbname], Dbschema, usage: dbschema [-t tabname]–d dbname [filename]

1. c file generation by preprocessor according to the. ec file

2, the system specified by the compiler to compile the. c file into obj file

3, by the system connector to the obj file and static library file connection, generate executable file

So you must specify the appropriate compiler for $CC, GCC or g++

Add environment variables after installing Informix under Linux

Ld_library_path= $INFORMIXDIR/lib:$/informixdir/lib/esql: $LD _library_path;

Export Ld_library_path;

Programming

Include header file: EXEC SQL include "dbdef.h";

Predefined variables: EXEC SQL define MaxLen 64;

To define a variable:

EXEC SQL BEGIN DECLARE section;

Char fname[maxlen+1];

EXEC SQL end DECLARE section;

To open a database:

EXEC SQL connect to ' dbname ';

To close the database:

EXEC SQL Disconnect current;

Define Cursor

EXEC SQL declare cursorname cursor FOR SELECT ...

Open cursor

EXEC SQL Open cursorname;

Reading data

EXEC SQL fetch cursorname;

Determine if the operation was successful

Sqlcode==0

Determine if the data is over

if (sqlcode==100);

Or in the following way:

Copy Code code as follows:

$include "Appdef.h";

$define MaxLen 64;

$char fname[maxlen+1];

$database dccdb;

$declare cursorname cursor for SELECT ...;

$open Cursorname;

$fetch Cursorname;

$close Cursorname;

$free Cursorname;

$disconnect Current

The following is the writing of makefile, be sure to link library functions, or there will be errors

Copy Code code as follows:

cc=gcc
exec01:exec01.o
Esql-o exec01-l$ (informixdir)/lib EXEC01.O
EXEC01.O:
Esql-c-i$ (informixdir)/incl/esql exec01.ec
Clean
Rm-f exec01 *.o exec01.c exec01