resultset

How to convert ResultSet object to one specific POJO class object?

由 倾然丶 夕夏残阳落幕 提交于 2019-12-22 00:49:31
问题 For example i have a Resultset which contain Details about Employee details and I have a table For Employee in database and i am selecting all details from that I have java POJO class which resembles Employee Table what is the best method to implement convert result set into Employee class object what is the best way to implement if i have multiple classes Like Employee and multiple tables too how to write a reusable code. I am Using following notation now. public Employee{ private int empId;

could not extract ResultSet

由 萝らか妹 提交于 2019-12-21 12:07:55
问题 public class DBUtilU { private static Session scss; private static SessionFactory sfactory; static { Configuration cfg = new Configuration(); cfg.addAnnotatedClass(Userdetails.class); cfg.addAnnotatedClass(Code.class); cfg.addAnnotatedClass(Messages.class); cfg.addAnnotatedClass(Comments.class); cfg.configure(); new SchemaExport(cfg); sfactory = cfg.buildSessionFactory(); } } public static List<Code> searchCodeTags(String tags) { List<Code> codelist = new ArrayList<Code>(); try { scss =

将JDBC ResultSet结果集转成List

由 ♀尐吖头ヾ 提交于 2019-12-21 07:05:31
private List<Map<String, Object>> list = new ArrayList<Map<String,Object>>(); public String queryAll() { Connection conn = null; Statement sta = null; ResultSet rs = null; try { Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/easyui", "root", "root"); sta = conn.createStatement(); rs = sta.executeQuery("select * from e_user"); ResultSetMetaData md = rs.getMetaData(); //获得结果集结构信息,元数据 int columnCount = md.getColumnCount(); //获得列数 while (rs.next()) { Map<String,Object> rowData = new HashMap<String,Object>(); for (int i = 1; i <= columnCount;

How to speed up table-retrieval with MATLAB and JDBC?

由 巧了我就是萌 提交于 2019-12-21 05:04:13
问题 I am accessing a PostGreSQL 8.4 database with JDBC called by MATLAB. The tables I am interested in basically consist of various columns of different datatypes. They are selected through their time-stamps. Since I want to retrieve big amounts of data I am looking for a way of making the request faster than it is right now. What I am doing at the moment is the following: First I establish a connection to the database and call it DBConn . Next step would be to prepare a Select-Statement and

学习Spring Data JPA

由 微笑、不失礼 提交于 2019-12-21 00:26:27
简介 Spring Data 是spring的一个子项目，在官网上是这样解释的： Spring Data 是为数据访问提供一种熟悉且一致的基于Spring的编程模型，同时仍然保留底层数据存储的特​​殊特性。它可以轻松使用数据访问技术，可以访问关系和非关系数据库。 简而言之就是让访问数据库能够更加便捷。 Spring Data 又包含多个子项目： Spring Data JPA Spring Data Mongo DB Spring Data Redis Spring Data Solr 本文章主要介绍Spring Data JPA的相关知识： 传统方式访问数据库 使用原始JDBC方式进行数据库操作 创建数据表： 开发JDBCUtil工具类 获取Connection，释放资源，配置的属性放在配置文件中，通过代码的方式将配置文件中的数据加载进来。 package com.zzh.util; import java.io.InputStream; import java.sql.*; import java.util.Properties; public class JDBCUtil { public static Connection getConnection() throws Exception { InputStream inputStream = JDBCUtil.class

ResultSet: Exception: set type is TYPE_FORWARD_ONLY — why?

由 久未见 提交于 2019-12-20 18:29:18
问题 I have very simple code: pstat=con.prepareStatement("select typeid from users where username=? and password=?"); pstat.setString(1, username); pstat.setString(2, password); rs=pstat.executeQuery(); int rowCount=0; while(rs.next()) { rowCount++; } rs.beforeFirst(); if(rowCount>=1) { while(rs.next()) { typeID=rs.getInt(1); } But when execute this code I am getting... java.sql.SQLException: Result set type is TYPE_FORWARD_ONLY at sun.jdbc.odbc.JdbcOdbcResultSet.beforeFirst(Unknown Source) at

Flink 自定义Source 读取Mysql

由 吃可爱长大的小学妹 提交于 2019-12-20 16:50:48
object CustomSource { def main(args: Array[String]): Unit = { val env: StreamExecutionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment val stringDataStream: DataStream[Provience] = env.addSource(new MySQLSource()) stringDataStream.print("Provience Record") env.execute } } class MySQLSource() extends RichSourceFunction[Provience] { var ps: PreparedStatement = _ var connection: Connection = _ var resultSet: ResultSet = _ override def open(parameters: Configuration): Unit = { super.open(parameters) val driver = "com.mysql.jdbc.Driver" val url = "jdbc:mysql://hadoop100:3306/test

Python, how to check if a result set is empty?

由 瘦欲@ 提交于 2019-12-20 10:59:43
问题 I have a sql statement that returns no hits. For example, 'select * from TAB where 1 = 2' . I want to check how many rows are returned, cursor.execute(query_sql) rs = cursor.fetchall() Here I get already exception: "(0, 'No result set')" How can I prevend this exception, check whether the result set is empty? 回答1: cursor.rowcount will usually be set to 0. If, however, you are running a statement that would never return a result set (such as INSERT without RETURNING , or SELECT ... INTO ),

Where to close a JDBC Connection while I want to return the ResultSet

由 ﹥＞﹥吖頭↗ 提交于 2019-12-20 09:37:16
问题 It seems that the ResultSet will be automatically closed when I close the Connection . But I want to return the ResultSet and use it in another method, then I don't know where to close Connection and PreparedStatement . public ResultSet executeQuery(String sql, String[] getValue) { Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; try { conn = getConn(); pstmt = conn.prepareStatement(sql); if (getValue != null) { for (int i = 0; i < getValue.length; i++) { pstmt

How to connect to 3 different databases and run Queries Parallel through JDBC

由 你离开我真会死。 提交于 2019-12-20 07:27:38
问题 I have a code where it connects to 3 databases, and runs one query on each database. This is done sequentially. 1) First I have put 3 Queries in a property file. 2) I iterate the Property file and store the Queries in one Array List. while((propData=reader.readLine())!=null) { /* ....... Iterates the prop file ...... */ } I have stored the query which I got from Property file in one Array List. ArrayList<String> list = new ArrayList<String>(); Then I iterated over the list, get each Query ,
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