java online book store (2) Category module

The example of this paper is to share the java online book store Category module code for your reference, the specific content is as follows

sql

CREATE TABLE `t_category` (
 `cid` char(32) NOT NULL,
 `cname` varchar(50) DEFAULT NULL,
 `pid` char(32) DEFAULT NULL,
 `desc` varchar(100) DEFAULT NULL,
 `orderBy` int(11) NOT NULL AUTO_INCREMENT,
 PRIMARY KEY (`cid`),
 UNIQUE KEY `cname` (`cname`),
 KEY `FK_t_category_t_category` (`pid`),
 KEY `orderBy` (`orderBy`),
 CONSTRAINT `FK_t_category_t_category` FOREIGN KEY (`pid`) REFERENCES `t_category` (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=48 DEFAULT CHARSET=utf8;　

Dao

public List<Category> findAll() throws SQLException {
 /*
  * 1.  Query out all 1 Grade classification 
  */
 String sql = "select * from t_category where pid is null order by orderBy";
 List<Map<String,Object>> mapList = qr.query(sql, new MapListHandler());
  
 List<Category> parents = toCategoryList(mapList);
  
 /*
  * 2.  Loop through all of them 1 Level classification for each 1 Class to load it 2 Grade classification 
  */
 for(Category parent : parents) {
  //  Queries for all child classes of the current parent class 
  List<Category> children = findByParent(parent.getCid());
  //  Sets the parent category 
  parent.setChildren(children);
 }
 return parents;
}

left.jsp

The Q6MenuBar component displays the accordion drop-down menu

<script language="javascript">
$(function() {
....
<c:forEach items="${parents}" var="parent">
 <c:forEach items="${parent.children}" var="child">
 bar.add("${parent.cname}", "${child.cname}", "/goods/BookServlet?method=findByCategory&cid=${child.cid}", "body");
 </c:forEach>
</c:forEach>
 
});
</script>