MySql:#1467 – Failed to read auto-increment value from storage engine

Categories: Database; Tagged with: ; @ March 14th, 2010 23:31

某日, mySql(5.1.30-community)如此报错, 用phpMyAdmin强行插入, 亦是如此:

image

但如直接指定Auto-Increment的 Field, 就可顺利插入.

解决:

修改该自增Filed的属性, 先将其自增属性点掉:

image

保存后, 再点选其自增, 再保存, 问题暂时解决.

英文水平有限, 暂不深究….

使用MysqlWorkbench 生成mysql反向工程

Categories: Database; Tagged with: ; @ April 1st, 2009 14:44

首先将MySQL数据库导出, 可使用PhpMyAdmin等工具,

打开WorkBench, File > import > Reverse Enginner MySQL Create Script…

选择导出的mysql文件, 确定即可.

image

SQL Reserved Words Checker – SQL保留字查询

Categories: Database; Tagged with: ; @ March 29th, 2009 11:21

支持数据库:

SQL Server, MySQL, PostgreSQL, Oracle, DB2, ANSI SQL, ODBC

地址:http://www.petefreitag.com/tools/sql_reserved_words_checker/

演示: 

image

Flex BlazeDS Java JDBC MySql 快速配置

Categories: FlexJava; Tagged with: ; @ February 20th, 2009 16:48

从下往上:image

1. Java – JDBC – MySql

1. 装好MySql, 启动服务.

2. 将mysql-connector-java-5.1.7-bin.jar 拖入WEB-INF/lib下.

搞定.

2. Java端BlazeDS配置

1. Java端:

将BlazeDS压缩包内的WEB-INF里面的东西拷贝工程内的WEB-INF下的相应位置中.[ Flex目录下有四个xml配置文件, lib下是需要使用的jar] 包括web.xm

2. 配置services-config.xml中channels标签中的内容:

  

        
            
        

        
            

                false
            
        

        
            

true
4
            
        

其中, http://localhost:8080/DepartmentManagement/ 是该Web工程的地址 [可在web-content下建立一空index.html, 运行后查看地址便可]

3. 编写Java类, 并配置remoting-config.xml文件的<service>标签下, 增加服务, 如下:

     

         com.insprise.guoliang.DepartmentManagement
       

3. Flex端建立工程

1. 建立 Flex与Java通信载体RemoteObject

为方便在整个工程中使用, 可建立一个Singleton – 关于AS中的Singleton可见: http://liguoliang.com/2008/10/128/

在该类中建立RemoteObject.

首先需要确定RemoteObject的destination, 在本例中 为”DepartmentManagement”; – 在remoting-config.xml中已配置.

其次需要确定ro的channel – 本例中为:”http://localhost:8080/DepartmentManagement/messagebroker/amf"; - 在services-config.xml中已配置

代码:

	public static const DEFAULT_DEST:String = "DepartmentManagement";
	public static const DEFAULT_CHANNEL_URL:String = "http://localhost:8080/DepartmentManagement/messagebroker/amf";
	private static var _ro:RemoteObject;

	/**
	 * Constractor - Singleton
	 */
	 public function AppContext():void {
	 	throw new Error("AppContext is Singleton!");
	 }

	/**
	 * Get RemoteObject
	 */
	public static function getRemoteObject():RemoteObject {
		if(_ro == null) {
			_ro = createRemoteObject(DEFAULT_DEST, DEFAULT_CHANNEL_URL);
		}
		return _ro;
	}

	/**
	 * Constructs a new remote object with new channel.
	 * @param roDestination Destination of the RemoteObject; should match a destination name in the services-config.xml file.
	 * @param channelURI the URI used to create the whole endpoint URI for this channel; this uri can be relative uri (to the folder containing the SWF).
	 * @param channelId the id of the channel, if set to null, a random Id will be assigned.
	 */
	protected static function createRemoteObject(roDestination:String, channelURI:String, channelId:String = null):RemoteObject {
		var channelSet:ChannelSet = new ChannelSet();
		var channel:AMFChannel = new AMFChannel(channelId == null ? "channel-" : channelId, channelURI);	//Create new Channel
		channelSet.addChannel(channel);	

		var ro:RemoteObject = new RemoteObject(roDestination);
		ro.channelSet = channelSet;

		return ro;
	}

4 配置完成,.

在Java端建立相关的Class,

启动服务器.

在Flex端通过 Appcontext.getRemoteObject.getOperation(“方法名称”)来调用服务器端方法.

具体实例:

Java端的Class – 通过JDBC 读取 MySql中数据:

	/**
	 * Load all Department and return an ArrayList
	 * @return
	 */
	public ArrayList loadDepartments() {
		ArrayList departmentsAL = new ArrayList();
		log.info("Loading Departments...");
		try {
			//Get Connection
			Connection conn = JdbcUtilities.getConnection();
			//Create statement
			String sql = " SELECT * FROM Department d ORDER BY d.Department_ID";
			PreparedStatement ps = conn.prepareStatement(sql);

			ResultSet res = ps.executeQuery();
			log.debug("Exectuing: " + sql);
			while (res.next()) {
				int id = res.getInt("Department_ID");
				String name = res.getString("name");

				Department dp = new Department();
				dp.setId(id);
				dp.setName(name);
				departmentsAL.add(dp);
				log.debug("从数据库获得部门:  " + dp);
			}
			JdbcUtilities.closeConn(res, ps, conn);
			log.info("加载部门信息结束, 共加载部门: " + departmentsAL.size());
		} catch (Exception e) {
			log.error("SQL Error", e);
			throw new Error(e);
		}
		return departmentsAL;

	}

Flex端的代码:

		/**
	 * Load the Department's Employee
	 */

	private var op:AbstractOperation;
	public function loadEmployees():void {
		op = AppContext.getRemoteObject().getOperation("loadEmployees");	//获得Operation
		 op.arguments = [id];	//设定参数
		 var at:AsyncToken = op.send();	//Send
		 at.addResponder(this);	//为本实例增加responder

      }

Flex端responder剩余代码见:http://liguoliang.com/2009/02/777/

运行Flex工程, Flex取得RemoteObject, 然后通过channel建立到destination的连接,由Java读取数据库中信息, 并返回给Flex.

JDBC中Preparedstatement使用小结 及JDBC插入数据后获得Last insert ID

Categories: Java; Tagged with: ; @ February 19th, 2009 10:20

编写SQL语句, 尤其是要插入多个Filed时, 是一件非常BT的事情, 至少让我很不爽, 使用preparedstatement可以使代码变得更优雅一些, 虽然会有些长, 但会更条理, 而且preparedstatement更高于SQL语句 – 相对来说不太容易随着数据库版本改变而变动. 另外preparedstatement效率更高, 安全性更好

下面是恐怖的SQL:

			Statement statement = (Statement) conn.createStatement();
			String sql = "INSERT INTO `DEP`.`employee` " +
					"( `name` , `age` , `address` , `isMale` , `level` , `Department_ID` ) " +
					"VALUES (" +
					"'" + emp.getName() + "', " +
					emp.getAge()  + ", " +
					 JdbcUtilities.getSqlForString(emp.getAddress()) + ", " +
					emp.getIsMale() + ", "  +
					emp.getLevel() + ", " +
					emp.getDepartment_ID() + ");"
					;

			log.debug("Executing sql :" + sql);
			statement.executeUpdate(sql);

			ResultSet rs = statement.executeQuery("SELECT last_insert_id();");// .execute("SELECT last_insert_id();");
			if(rs.next()) {
				System.out.println(rs.getInt("1"));
			}

这里是使用PreparedStatement后的语句:

			String psql = "INSERT INTO Employee (name, age, address, isMale, level, Department_ID) VALUES (?, ?, ?, ?, ?, ?)";
			PreparedStatement ps  = conn.prepareStatement(psql,Statement.RETURN_GENERATED_KEYS);

			ps.setString(1, emp.getName());
			ps.setInt(2, emp.getAge());
			ps.setString(3, emp.getAddress());
			ps.setInt(4, emp.getIsMale());
			ps.setInt(5, emp.getLevel());
			ps.setInt(6, emp.getDepartment_ID());

			ps.executeUpdate();

			ResultSet keys = ps.getGeneratedKeys(); // equivalent to "SELECT last_insert_id();"

			if(keys.next()) {
				System.out.println(keys.getInt(1));
			}

PreparedStatement的使用步骤:

  1. 声明 PreparedStatement。

    PreparedStatement prepStmt;
  2. 将一条 SQL 语句指派给 PreparedStatement 对象。

    prepStmt = conn.prepareStatement(
       "INSERT INTO MyTable(MyColumn) values (?)");
  3. 为该语句指派输入参数值。

    以下代码显示一个字符串参数。

    String newValue;
    // assign value
    prepStmt.setStringParameter(1, newValue);
  4. 执行该语句。

    返回值表示受该语句影响的行数。

    long rowsInserted = prepStmt.executeStatement();
  5. 如果禁用了 [自动提交],请提交更改。

    conn.commit();

参考地址

获得组后插入的ID, 在上面代码中已经包括.

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