任何人都可以解释以下PHP代码？

Question

Can anyone explain what the following PHP Code does

---

function query($query_string) 
    {
        if ($query_string == "") {
            return 0;
        }

        if (!$this->connect()) {
            return 0; 
        };

        if ($this->QueryID) {
            $this->free_result();
        }

        if ($this->RecordsPerPage && $this->PageNumber) {
            $query_string .= " LIMIT " . (($this->PageNumber - 1) * $this->RecordsPerPage) . ", " . $this->RecordsPerPage;
            $this->RecordsPerPage = 0;
            $this->PageNumber = 0;
        } else if ($this->RecordsPerPage) {
            $query_string .= " LIMIT " . $this->Offset . ", " . $this->RecordsPerPage;
            $this->Offset = 0;
            $this->RecordsPerPage = 0;
        }

        $this->QueryID = @mysql_query($query_string, $this->LinkID);
        $this->Row   = 0;
        $this->Errno = mysql_errno();
        $this->Error = mysql_error();
        if (!$this->QueryID) {
            $this->halt("Invalid SQL: " . $query_string);
        }

        return $this->QueryID;
    }

---

function next_record() 
    {
        if (!$this->QueryID) {
            $this->halt("next_record called with no query pending.");
            return 0;
        }

        $this->Record = @mysql_fetch_array($this->QueryID);
        $this->Row   += 1;
        $this->Errno  = mysql_errno();
        $this->Error  = mysql_error();

        $stat = is_array($this->Record);
        if (!$stat && $this->AutoFree) {
            $this->free_result();
        }
        return $stat;
    }

---

Can the above be done in a simpler way , would it be wise to use an ORM ?

Answer 1

The first class method looks like it performs a MySQL query and adds a LIMIT clause for pagination. The second moves the current query onto the next record, while incrementing the pagination counters.

In more detail, here's the first sample:

• Exit the method if the query is empty or the database connection doesn't exist.
• Free any existing query.
• If the number of records per page and page number are set:
  • Add them to the LIMIT clause of the query.
  • And reset them to 0.
• Otherwise if records per page is set:
  • Add it to the LIMIT clause of the query.
  • And reset them to 0.
• Run the query.
• Set the current row to 0.
• Collect errors.
• If the query failed halt with the error.
• Return the query.

And the second:

• If the query is not set halt with an error.
• Fetch row information as an array for the current row.
• Increment the row number.
• Catch any errors.
• If the result isn't an array free/close the query.
• Otherwise return the result set.