Complete SQLDA Example with Data Type Handling and Output

54th chunk of `doc/src/sgml/ecpg.sgml`

03b0bec0b79fd0f86ce64c74defb853433dadc94ab6dd2180000000100000fa9

 cur_sqlda->desc_next)
        {
            int i;
            char name_buf[1024];
            char var_buf[1024];

            /* Print every column in a row. */
            for (i=0 ; i&lt;cur_sqlda->sqld ; i++)
            {
                sqlvar_t v = cur_sqlda->sqlvar[i];
                char *sqldata = v.sqldata;
                short sqllen  = v.sqllen;

                strncpy(name_buf, v.sqlname.data, v.sqlname.length);
                name_buf[v.sqlname.length] = '\0';

                switch (v.sqltype)
                {
                    case ECPGt_char:
                        memset(&amp;var_buf, 0, sizeof(var_buf));
                        memcpy(&amp;var_buf, sqldata, (sizeof(var_buf)&lt;=sqllen ? sizeof(var_buf)-1 : sqllen) );
                        break;

                    case ECPGt_int: /* integer */
                        memcpy(&amp;intval, sqldata, sqllen);
                        snprintf(var_buf, sizeof(var_buf), "%d", intval);
                        break;

                    case ECPGt_long_long: /* bigint */
                        memcpy(&amp;longlongval, sqldata, sqllen);
                        snprintf(var_buf, sizeof(var_buf), "%lld", longlongval);
                        break;

                    default:
                    {
                        int i;
                        memset(var_buf, 0, sizeof(var_buf));
                        for (i = 0; i &lt; sqllen; i++)
                        {
                            char tmpbuf[16];
                            snprintf(tmpbuf, sizeof(tmpbuf), "%02x ", (unsigned char) sqldata[i]);
                            strncat(var_buf, tmpbuf, sizeof(var_buf));
                        }
                    }
                        break;
                }

                printf("%s = %s (type: %d)\n", name_buf, var_buf, v.sqltype);
            }

            printf("\n");
        }
    }

    EXEC SQL CLOSE cur1;
    EXEC SQL COMMIT;

    EXEC SQL DISCONNECT ALL;

    return 0;
}
</programlisting>

     <para>
      The output of this example should look something like the
      following (some numbers will vary).
     </para>

<screen>
oid = 1 (type: 1)
datname = template1 (type: 1)
datdba = 10 (type: 1)
encoding = 0 (type: 5)
datistemplate = t (type: 1)
datallowconn = t (type: 1)
dathasloginevt = f (type: 1)
datconnlimit = -1 (type: 5)
datfrozenxid = 379 (type: 1)
dattablespace = 1663 (type: 1)
datconfig =  (type: 1)
datacl = {=c/uptime,uptime=CTc/uptime} (type: 1)
datid = 1 (type: 1)
datname = template1 (type: 1)
numbackends = 0 (type: 5)
xact_commit = 113606 (type: 9)
xact_rollback = 0 (type: 9)
blks_read = 130 (type: 9)
blks_hit = 7341714 (type: 9)
tup_returned = 38262679 (type: 9)
tup_fetched = 1836281 (type: 9)
tup_inserted = 0 (type: 9)
tup_updated = 0 (type: 9)
tup_deleted = 0 (type: 9)

oid = 11511 (type: 1)
datname = postgres (type: 1)
datdba = 10 (type: 1)
encoding = 0 (type: 5)
datistemplate = f (type: 1)
datallowconn = t (type: 1)
dathasloginevt = f (type: 1)
datconnlimit = -1 (type: 5)
datfrozenxid = 379 (type: 1)
dattablespace = 1663 (type: 1)
datconfig =  (type: 1)
datacl =  (type: 1)
datid = 11511 (type: 1)
datname = postgres (type: 1)
numbackends = 0 (type: 5)
xact_commit = 221069 (type: 9)
xact_rollback = 18 (type: 9)
blks_read = 1176 (type: 9)
blks_hit = 13943750 (type: 9)
tup_returned = 77410091 (type: 9)
tup_fetched = 3253694 (type: 9)
tup_inserted = 0 (type: 9)
tup_updated = 0 (type: 9)
tup_deleted = 0 (type: 9)
</screen>
    </example>
   </sect3>
  </sect2>
 </sect1>

 <sect1 id="ecpg-errors">
  <title>Error Handling</title>

  <para>
   This section describes how you can handle exceptional conditions
   and warnings in an embedded SQL program.  There are two
   nonexclusive facilities for this.

   <itemizedlist>
    <listitem>
     <simpara>
      Callbacks can be configured to handle warning and error
      conditions using the <literal>WHENEVER</literal> command.
     </simpara>
    </listitem>

    <listitem>

Title: Complete SQLDA Example with Data Type Handling and Output

Summary

This section presents the complete SQLDA example code, focusing on fetching data from the cursor and printing it. The code iterates through each column in a row, retrieving the column name and data. A switch statement handles different data types (ECPGt_char, ECPGt_int, ECPGt_long_long). If the data type doesn't match any of the cases, the code defaults to printing the raw byte representation of the data. The program then closes the cursor, commits changes, disconnects from the database, and shows example output from the executed SQL query.