数据库迁移的总结 --gx

首先数据库迁移的IP要配置正确，旧的–>新的
其次，数据库迁移要保证新、旧字段的匹配，要每个对应。

 public static void main(String[] args) {
	Connection con_origin = null;
	Connection con_destination = null;
	ResultSet rs = null;
	Statement st_ori = null;
	Statement st_des = null;
	//这里会用到try-catch-finally
	Class.forName("org.mariadb.jdbc.Driver");
	con_origin = DriverManager.getConnection("jdbc:mysql://旧IP地址:3306/tdb?useUnicode=true&characterEncoding=UTF-8", "root", "123456");
	con_destination = DriverManager.getConnection("jdbc:mysql://新IP地址:3306/config_cbtc2_atp?useUnicode=true&characterEncoding=UTF-8", "root", "123456");
	st_ori = con_origin.createStatement();
	st_des = con_destination.createStatement();
	
 // 迁移TestTable工程表数据
transferTestTable(rs,st_ori,st_des);

数据迁移的方法及格式：

private static void transferTestTable(ResultSet rs,Statement st_ori,Statement st_des){			

int i = 0;
try {
	String query_sql = " select * from linetable ";
		rs = st_ori.executeQuery(query_sql);
		while (rs.next()) {
				// 将查询出的内容添加到list中，其中userName为数据库中的字段名称
				//System.out.println(rs.getString("name"));
				String del_sql = " delete from linetable where id = "+"'"+rs.getString("id")+"'";
				st_des.execute(del_sql);
				String insert_sql = " insert into artable(id,creator,gmt_create,is_deleted,"
		            		 + "project_id,"
		            		 + "sortud,"
		            		 + "atp_device_no,"		            		
		            		 + "n_id_track1,"
		            		 + "n_id_track2,"
		            		 + "n_id_track3,"
		            		 + "n_id_track4) values("+"'"+rs.getString("id")+"',"
		           		+"'"+rs.getString("creator")+"',"
		           		+"'"+rs.getString("create_time")+"',"
					  	+"0,"
					  	+"'"+rs.getString("projectid")+"',"
					  	+"'"+rs.getString("SortUD")+"',"
					  	+"'"+rs.getString("NID_AR_AREA")+"',"
					  	+"'"+rs.getString("NID_LINE")+"',"
					  	+"'"+rs.getString("N_TRACK")+"',"
					  	+"'"+rs.getString("NID_TRACK1")+"',"
					  	+"'"+rs.getString("NID_TRACK2")+"',"
					  	+"'"+rs.getString("NID_TRACK3")+"',"
					  	+"'"+rs.getString("NID_TRACK4")+"'"						  				     
		           		+") ";
		              //System.out.println(insert_sql);
					  st_des.execute(insert_sql);
					  i++;
				}
			} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
			} finally{
				try {
				rs.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
			}
		}
	System.out.println("插入line数据条数为"+i+"条。");
}

注意：在上述迁移的过程中

遇到的问题：
1、报错数据不匹配（查看insert和values后的内容是一一对应的）；
报错数据为空（加保护程序if-else。判断为空时和不为空时应该执行的语句）；
报错空指针（该问题复杂，建议打印输出看结果在做相应的处理）；
报错格式问题（1、insert最后没有分号；2、insert最后之前的引号中要加入逗号【,】；3、values 最后一个getString引号中没有逗号；4、values最后之前的getString引号中有逗号【,】；）

2、出现组合的情况时，可以使用借用德摩根定律。
德摩根定律：出现多种情况可以用if-else的嵌套；
3、有些变量值会有其他的问题可以单独处理；
例如：
String ATTR_uSTOP="";
String ATTR_dSTOP="";

 while (rs.next()) {
	            // 将查询出的内容添加到list中，其中userName为数据库中的字段名称
	             //System.out.println(rs.getString("name"));
				 String ATTR_uSTOP="";
				 String ATTR_dSTOP="";
				
	             String del_sql = " delete from balisetable where id = "+"'"+rs.getString("id")+"'";
	             st_des.execute(del_sql);
	          
	             String insert_sql = "";
	             if (null == rs.getString("SortUD")){		          	
	            	   		
	            	  insert_sql = " insert into balisetable(id,creator,gmt_create,is_deleted,"
		            		 + "project_id,"
		            		 + "sortud,"
		            		 + "atp_device_no,"			            		
		            		 + "attrustop,"
		            		 + "attrdstop,"			            		
		            		 + "m_version_bal) values("+"'"+rs.getString("id")+"',"
		           		+"'"+rs.getString("creator")+"',"
		           		+"'"+rs.getString("create_time")+"',"
					  	+"0,"
						+"'"+rs.getString("ProjectID")+"',"
						+"0,"
						+"'"+rs.getString("NID_BALISE")+"',"							
						+"'"+rs.getString("ATTR_uSTOP")+"',"
						+"'"+rs.getString("ATTR_dSTOP")+"',"							
						+"'"+rs.getString("M_VERSIONBAL")+"'"						
		           		+") ";
	                 }				 		             
	             else {
	            	 if(null == rs.getString("ATTR_uSTOP")||rs.getString("ATTR_uSTOP")==""){
	            		 ATTR_uSTOP="'"+rs.getString("ATTR_uSTOP")+"',";
	            	 }
	            	 else{	            		
		            	 if(rs.getString("ATTR_uSTOP").equals("1")){
		            		 ATTR_uSTOP="'"+"0x0001"+"',";
		            	 }
		            	 else{		            		
		            		 ATTR_uSTOP="'"+rs.getString("ATTR_uSTOP")+"',";
		            	 }
	            	 }		            	 
	            	 
	            	 if(null == rs.getString("ATTR_dSTOP")||rs.getString("ATTR_dSTOP")==""){
	            		 ATTR_dSTOP="'"+rs.getString("ATTR_dSTOP")+"',";
	            	 }
	            	 else{	            		
		            	 if(rs.getString("ATTR_dSTOP").equals("2")){
		            		 ATTR_dSTOP="'"+"0x0002"+"',";
		            	 }
		            	 else{		            		
		            		 ATTR_dSTOP="'"+rs.getString("ATTR_dSTOP")+"',";
		            	 }
	            	 }	           	 
	           insert_sql = " insert into balisetable(id,creator,gmt_create,is_deleted,"
	            		 + "project_id,"
	            		 + "sortud,"
	            		 + "atp_device_no,"		            		
	            		 + "attrustop,"
	            		 + "attrdstop,"		            		
	            		 + "m_version_bal) values("+"'"+rs.getString("id")+"',"
	           		+"'"+rs.getString("creator")+"',"
	           		+"'"+rs.getString("create_time")+"',"
				  	+"0,"
					+"'"+rs.getString("ProjectID")+"',"
					+"'"+rs.getString("SortUD")+"',"
					+"'"+rs.getString("NID_BALISE")+"',"					
					+ATTR_uSTOP
					+ATTR_dSTOP					
					+"'"+rs.getString("M_VERSIONBAL")+"'"						
					+") ";
	             }		            
	              //System.out.println(ATTR_uF);		            
				  st_des.execute(insert_sql);
				  i++;					  
			}
		 }

4、新旧导出的Excel表有其中两行的某些字段不一致：分三步检查，检查前端、数据库（数据的查询操作）、后台。前端显示一致，而后台的新旧代码逻辑一致，问题出现在数据库中，数据虽然一致，但是，排序的依据一致，但是根据排序的依据检查，发现数据库中的两组数据不一致，一种是int型排序，另一种是字符串排序。int排序按照常规的大小；字符串排序根据第一位排序例如：1，10，11；之后再看第一位是2的。
解决方法：字符串+0 强制转化为数字型，这样就可以按照int的方法比较了。

5、数据库中为灰色的（Null），赋值时直接可以赋值为大写NULL；
6、进制转换问题

//十六进制转换为十进制
cell.setCellValue(Integer.parseInt(po.getAttrDStop().replaceAll("0x", ""),16));

//进制转换注意长度可能超过，要是用Long，Integer.valueOf和他的区别，trim（）是删除前后的空格，Long.parseLong

项目心得：
1、首先解决问题要一个一个来，不建议合并解决，当然类似问题可以这样处理；
2、查找不出原因的时候可以采用跟代码、debug的调试方式来查找问题的根源；
3、注意代码中的细节问题，例如：标点符号、名称的一致性、逻辑关系，同结构的代码复制的时候注意修改不一样的地方。总之归结为细节问题；
4、注意报错的类型，根据报错提示去修改代码。