resultset

学习日志--------JDBC（07）

由 江枫思渺然 提交于 2019-12-11 01:05:19
元数据： 什么是元数据 ? 就是 获取数据的 数据 就是 元数据; 它是从 ResultSet结果集中 获取的; 通过api 来学习 ResultSetMetaData 元数据 通过 getMetaData() 方法 可以 查询出 此 ResultSet对象的列的数量，类型和属性 数量 count ，类型 type ， 属性 property 这个方法 是ResultSet结果集的结构; 介绍ResultSetMetaData 中的常用方法 重要： int getColumnCount(); 返回此 ResultSet对象中的列数。 2)String getColumnName(int column); 获取指定列的名称。 3)String getTableName(int column); 获取指定列的表名称。 package com.oracle.daoImpl; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import com.oracle.enity.User; import com.oracle.util

java技术--原生态JDBC

由 旧巷老猫 提交于 2019-12-10 20:08:49
1.传统的JDBC来做DAO层，做了下面这几件事： （1）加载驱动 （2）获取连接 （3）执行SQL语句 （4）获取操作结果封装信息 （5）返回操作结果 2.原始的JDBC程序代码连接数据库，操作数据 package com . utils ; import java . sql . Connection ; import java . sql . DriverManager ; import java . sql . PreparedStatement ; import java . sql . ResultSet ; import java . sql . SQLException ; /** * @ClassName: JdbcTest * @Description: TODO(原始的JDBC操作数据库) */ public class JdbcTest { public static void main ( String [ ] args ) { // 数据库连接 Connection connection = null ; // 预编译的Statement，使用预编译的Statement提高数据库性能 PreparedStatement preparedStatement = null ; // 结果集 ResultSet resultSet = null ; try {

SQLException: the result set is closed

由 梦想与她 提交于 2019-12-10 19:12:23
问题 I am a beginner in Java using NetBeans and I was trying to create something similar to a faculty registration system. I use SQL Server 2005 to create the DB. During the implementation I was trying to create a function to make students able to register their subjects so the function basically searches for the subjects that the student has finished their prerequisites. So I wrote the following code: package GUIs; import java.sql.*; import javax.swing.*; public class AddSubToStd extends javax

Can I make Lucene return an unlimited number of search results?

由 送分小仙女□ 提交于 2019-12-10 15:36:58
问题 I am using Lucene 3.0.1 in a Java 5 environment. I've been researching this issue a little bit, but the documentation hasn't given any direct answers. Using the search method TopFieldDocs search(Weight weight, Filter filter, int nDocs, Sort sort) I always need to provide a maximum number of search results nDocs . What if I wanted to have all matching results? It feels like setting nDocs to Integer.MAX_VALUE is a kind of hacky way to do this (and would result in speed and memory performance

Problem with SQL, ResultSet in java

由 南笙酒味 提交于 2019-12-10 14:33:19
问题 How can I iterate ResultSet ? I've tried with the following code, but i get the error java.sql.SQLException: Illegal operation on empty result set. while ( !rs.isLast()) { rs.next(); int id = rs.getInt("person_id"); SQL.getInstance().getSt().execute("INSERT ref_person_pub(person_id) VALUES(" + id + ")"); } Update: I've found the problem. I have used only one statement from the SQL singleton. When the statement is closed it can't be used again. 回答1: As per the JDBC tutorial: resultSet =

could not extract ResultSet; nested exception is org.hibernate.exception.GenericJDBCException: could

由 你离开我真会死。 提交于 2019-12-10 12:15:10
could not extract ResultSet; nested exception is org.hibernate.exception.GenericJDBCException: could not extract ResultSet 使用@Query更新了数据，却没有添加注解导致调用了错误的方法。 添加这两个注解： @Transactional @Modifying 来源： CSDN 作者： weixin_42931631 链接： https://blog.csdn.net/weixin_42931631/article/details/103472193

Execute SQL from Python: Format the result set [duplicate]

由 心已入冬 提交于 2019-12-10 11:57:19
问题 This question already has answers here : Printing Lists as Tabular Data (12 answers) Closed 2 years ago . I have a python script that lets me query a GIS database using SQL in Python: import sys import arcpy try: arcpy.env.workspace = sys.path[0] egdb_conn = arcpy.ArcSDESQLExecute(r"Database Connections\Connection1.sde") --> sql_statement = """SELECT * FROM USER1.A_TEST_TABLE""" sql_statement_list = sql_statement.split(";") print("+++++++++++++++++++++++++++++++++++++++++++++\n") # For each

display resultset from oracle 10g stored procedure

由 一笑奈何 提交于 2019-12-10 10:38:27
问题 I am using PL/SQL Developer and i have written a procedure to run a report and i need to procedure to output the resultset. The procedure accepts input parameters and needs to output the resultset. I cannot use a view because the procedure calls several APIs which accept the parameters i am passing into the procedure. I understand from alot of searching that it's possible using ref_cursor but i cannot get ti to work. A simplified version of the procedure is: CREATE OR REPLACE PROCEDURE

JDBC ResultSet object types mapping has no Byte or Short? Why Integer only?

由 社会主义新天地 提交于 2019-12-10 10:29:36
问题 Good day. Can anyone explain why JDBC doesn't implement object mapping for some types. For example, Postgres JDBC has no Byte and Short mapping. I can get primitive byte and short, but in object format I can get only Integer. This is source code from here case Types.TINYINT: case Types.SMALLINT: case Types.INTEGER: return getInt(columnIndex); What's wrong wtih Byte and Short object types? How can I work with TINYINT, SMALLINT and so on. What's problem to implement getByte and getShort similar

文件 流转

由 為{幸葍}努か 提交于 2019-12-10 07:50:25
连接数据库 import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import org.apache.catalina.User; import com.official.bean.Doc; import com.official.bean.Permission; import com.official.bean.Users; public class DBUtil { //数据库URL和账号密码 private static final String connectionURL="jdbc:mysql://127.0.0.1:3306/doc-system?useUnicode=true&characterEncoding=GB18030&useSSL=false&serverTimezone=GMT&allowPublicKeyRetrieval=true"; private static final String username="root"; private static
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