MySQL Trigger | MySQL Before/After Insert Trigger | MySQL Before/After Update Trigger | MySQL Before/After Delete Trigger

MySQL Trigger | MySQL Before/After Insert Trigger | MySQL Before/After Update Trigger | MySQL Before/After Delete Trigger:

DROP TRIGGER IF EXISTS `example_table_before_insert`;
DELIMITER $$
CREATE TRIGGER `example_table_before_insert`
BEFORE INSERT ON `example_table` FOR EACH ROW BEGIN
  DECLARE ready INT DEFAULT 0;
  DECLARE rnd_str TEXT;
  IF NEW.CODE IS NULL OR CHAR_LENGTH(NEW.CODE) = 0 THEN
    WHILE NOT ready DO
      SET rnd_str := UPPER(SUBSTR(MD5(CONCAT(rand(), now())), 1, 5));
      IF NOT exists(SELECT * FROM example_table WHERE CODE = rnd_str) THEN
        SET NEW.CODE = rnd_str;
        SET ready := 1;
      END IF;
    END WHILE;
  END IF;
END
$$
DELIMITER ;

DROP TRIGGER IF EXISTS `example_table_before_update`;
DELIMITER $$
CREATE TRIGGER `example_table_before_update`
BEFORE UPDATE ON `example_table` FOR EACH ROW BEGIN
  DECLARE ready INT DEFAULT 0;
  DECLARE rnd_str TEXT;
  IF NEW.CODE IS NULL OR CHAR_LENGTH(NEW.CODE) = 0 THEN
    WHILE NOT ready DO
      SET rnd_str := UPPER(SUBSTR(MD5(CONCAT(rand(), now())), 1, 5));
      IF NOT exists(SELECT * FROM example_table WHERE CODE = rnd_str) THEN
        SET NEW.CODE = rnd_str;
        SET ready := 1;
      END IF;
    END WHILE;
  END IF;
  SET NEW.updated_at = now();
END
$$
DELIMITER ;

DROP TRIGGER IF EXISTS `example_table_after_delete`;
DELIMITER $$
CREATE TRIGGER `example_table_after_delete`
AFTER DELETE ON `example_table` FOR EACH ROW BEGIN
  DELETE FROM example_table_associations WHERE example_id=OLD.id;
END
$$
DELIMITER ;

SCRIPT5 Access denied on form submit in IE if file is triggered

SCRIPT5 access denied is a problem when you want to trigger a input[type='file'] element on internet explorer(ie). Most of the browsers like mozilla, opera working by just triggering click on the file input field. But internet explorer(ie) does not like this and think this it as violation of access. So we just can put the file inside a div and make the input area whole around as div area. So when one click on the div, actually it clicks on the input element and open file selection dialog. And ie is now happy with it.
See the full result in jsFiddle.

jsFiddle view

Html and css

<div class="file_upload_section">
    <span>Click to upload</span>
    <input type="file" name="upload_file" />
</div>

<style type="text/css">
    div.file_upload_section {
        position: relative;
        background-color: yellow;
        padding: 20px; 

        font-weight: bold; 

        overflow: hidden;
    }
    
    div.file_upload_section input[type=file] {
        position: absolute;
        right: 0px;
        top: 0px;
        font-size: 2000px;
        height: 100%;
        opacity: 0;
        z-index: 1000;
        width: 100%;
    }
</style>

Additional jQuery code

$("div.file_upload_section").click(function() {
    var file = $(this).find("input[name='upload_file']");
    file.change(function() {
        var fileName = "Uploading: " + $(this).val().split("\\").pop();
        file.closest("div.file_upload_section").find("span").html(fileName);
    });
});