Help with Embedded SQL

Can someone help me understand what is happening in this code. I am confused about what is being done in the structure INTFC_LKUP which I posted below the code. Thanks.

Code:

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  1042    EXEC SQL SELECT remote_host, ftp_cmd, src_dir, dest_dir,
  1043        xfer_dir, notify_flag
  1044    INTO :intfc_lkup.remote_host, :intfc_lkup.ftp_cmd, :intfc_lkup.src_dir,
  1045        :intfc_lkup.dest_dir, :intfc_lkup.xfer_dir,
  1046        :intfc_lkup.notify_flag
  1047    FROM intfc_lkup
  1048    WHERE intfc_nm = :intfc_lkup.intfc_nm;



typedef  struct {
    char    intfc_nm[26];
    char    remote_host[26];
    char    ftp_cmd[7];
    char    src_dir[151];
    char    dest_dir[151];
    char    xfer_dir[151];
    char    notify_flag[2];
    char    ftp_username[26];
    char    ftp_password[26];
  } INTFC_LKUP;

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Again, this is DB2 SQL. All the variable names with colons in front of them are referred to as "host variables". The DB2 precompiler will process this C source code and turn the SQL into C code that builds a structure (it's own structure, not yours) with pointers to all these values. At run time, DB2 will then be called, and DB2 will place the values for all the host variables into their appropriate places, which in this case, happens to be in the structure you posted.

Since it's a SELECT INTO, only one row is expected to be returned to the application.

Is this a z/OS platform?

Todd

Thanks. I still am a little confused but looking online for more information. Please correct me if I am wrong. Which I am sure I am wrong. The SELECT grabs records from the db and INTO places these db records into my structure WHERE intfc_nm = :intfc_lkup.intfc_nm;? I am not a programmer yet but I am trying to learn 2 things at once (db and c programming) on my own so thanks for any patience you may have.

-Carl

Yes.

The table name is "intfc_lkup"

The columns being selected are: remote_host, ftp_cmd, src_dir, dest_dir, and xfer_dir, notify_flag

The value from column remote_host is being placed into intfc_lkup.remote_host.
The value from column ftp_cmd is being placed into intfc_lkup.ftp_cmd, and so on.

There is only one row expected to be returned, and the column intfc_nm has to equal the value already placed into variable intfc_lkup.intfc_nm.

SELECT INTO is a special case of SELECT combined with FETCH. Normally, you would do a PREPARE (or OPEN) for the SELECT statement, and then an OPEN CURSOR, followed by however many FETCH CURSOR INTO :var.... statements in a loop, then a CLOSE CURSOR. But, since only one row is being returned (defined by data and application logic), then it can all be combined into a SELECT INTO construct.

Todd

Your help is greatly appreciated. Thanks for taking time to answer my questions. It at least makes some sense now and I can apply what you just spelled out for me to other code I am running into.

-Carl