resultset

eclipse sql server 导出excel文件

由 那年仲夏 提交于 2020-01-16 05:46:36
Jxl.jar 访问Excel的Jar包 注意：支持以.xls结尾的Excel文件，可能不支持.xlsx结尾的 下载地址： 程序所需要得包： 程序代码: package partice; import java.io.File; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; import java.util.Date; import javax.swing.JOptionPane; import jxl.Workbook; import jxl.read.biff.BiffException; import jxl.write.Label; import jxl.write.WritableSheet; import jxl.write.WritableWorkbook; import jxl.write.WriteException; import jxl.write.biff.RowsExceededException

20.java-JDBC连接mysql数据库详解

由 走远了吗. 提交于 2020-01-14 17:55:49
1.JDBC介绍 jdbc (java database connectivity) 为java开发者使用数据库提供了统一的编程接口，它由一组java类和接口组成。 JDBC需要用到的类和接口有: DriverManager、Connection、Statement、ResultSet 2. mysql-connector-java下载 本机的mysql版本是5.7.26 win32的,所以本章访问mysql都以该版本为例: 然后进入 https://dev.mysql.com/downloads/connector/j/ 下载mysql-connector-java.jar包,用于连接mysql 如下图所示,只有8.0.19版本,那我们下载它就好了,反正不管64位还是32位都能访问: 下载解压后,就有个mysql-connector-java-8.0.19.jar: 接下来就来测试,能不能访问 3.JDBC使用过程 3.1 通过DriverManager. registerDriver( Driver driver)来注册驱动程序 需要注意,new Driver的时候,需要选择com.mysql.cj.jdbc.Driver: 因为com.mysql.jdbc.Driver已经被弃用了. PS: 也可以直接将 DriverManager. registerDriver

Joining two result sets into one

由 空扰寡人 提交于 2020-01-14 14:05:59
问题 I wanted to know if there's a way to join two or more result sets into one. I actually need to execute more than one query and return just one result set. I can't use the UNION or the JOIN operators because I'm working with Cassandra (CQL) Thanks in advance ! 回答1: Framework like Playorm provide support for JOIN (INNER and LEFT JOINs)queries in Cassandra. http://buffalosw.com/wiki/Command-Line-Tool/ You may see more examples at: https://github.com/deanhiller/playorm/blob/master/src/test/java

What is a solution of “Multiple ResultSets were returned by the query”

由 烈酒焚心 提交于 2020-01-14 09:32:58
问题 I get error: ERROR [NewsDAO] findAll(): org.postgresql.util.PSQLException: Multiple ResultSets were returned by the query. Im using postgresql-8.4-703.jdbc4.jar. My code looks like: private static StringBuilder findAllQuery = new StringBuilder(); { findAllQuery.append("SELECT * FROM news;"); } public List<News> findAll() { Statement stm = null; ResultSet rs = null; List<News> results = new ArrayList<News>(); if (obtainConnection()) { try { stm = con.createStatement(); rs = stm.executeQuery

What is a solution of “Multiple ResultSets were returned by the query”

由 為{幸葍}努か 提交于 2020-01-14 09:32:16
问题 I get error: ERROR [NewsDAO] findAll(): org.postgresql.util.PSQLException: Multiple ResultSets were returned by the query. Im using postgresql-8.4-703.jdbc4.jar. My code looks like: private static StringBuilder findAllQuery = new StringBuilder(); { findAllQuery.append("SELECT * FROM news;"); } public List<News> findAll() { Statement stm = null; ResultSet rs = null; List<News> results = new ArrayList<News>(); if (obtainConnection()) { try { stm = con.createStatement(); rs = stm.executeQuery

What is a solution of “Multiple ResultSets were returned by the query”

由 穿精又带淫゛_ 提交于 2020-01-14 09:32:09
问题 I get error: ERROR [NewsDAO] findAll(): org.postgresql.util.PSQLException: Multiple ResultSets were returned by the query. Im using postgresql-8.4-703.jdbc4.jar. My code looks like: private static StringBuilder findAllQuery = new StringBuilder(); { findAllQuery.append("SELECT * FROM news;"); } public List<News> findAll() { Statement stm = null; ResultSet rs = null; List<News> results = new ArrayList<News>(); if (obtainConnection()) { try { stm = con.createStatement(); rs = stm.executeQuery

How to make the resultset returned from oracle keeps its column aliases characters case

由 南笙酒味 提交于 2020-01-14 08:52:27
问题 I am trying to querying some sql statment againest oracle database. I am using Java ResultSetMetaData to get column alias names (through: rsmd.getColumnLable() ) The query looks like: select part_id partId, part_num partNumber from tbl; But the result set meta-data returns for me the aliases as partid and partnumber respectively ... But I need to get the aliases in the same characters case the user choose, so I need to get it as partId and partNumber respectively. How to accomplish that?

What happens to the original resultSet when it is returned from a method into a new object?

由 心不动则不痛 提交于 2020-01-14 06:12:26
问题 pseudo code to explain my self better. I'm learning Java at this point in time. if I have a method public resultSet getEverything() { resultSet rs = blabla; return rs } I can't rs.close() as I need to use it in the method I retrieve it hence then I will use it, and maybe 'close' the new resultSet I create. What happens from the previous resultSet? Is it left to be collected by the garbage collector? Does it close itself when I close the 'new' resultSet? Does it have any impact on code

What happens to the original resultSet when it is returned from a method into a new object?

由 别等时光非礼了梦想. 提交于 2020-01-14 06:12:08
问题 pseudo code to explain my self better. I'm learning Java at this point in time. if I have a method public resultSet getEverything() { resultSet rs = blabla; return rs } I can't rs.close() as I need to use it in the method I retrieve it hence then I will use it, and maybe 'close' the new resultSet I create. What happens from the previous resultSet? Is it left to be collected by the garbage collector? Does it close itself when I close the 'new' resultSet? Does it have any impact on code
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