第二十九章参数的元数据信息_mysql java parameter metadatanot available for the-优快云博客

本文介绍了一个Java JDBC示例，展示了如何使用PreparedStatement来执行带有参数的SQL查询，并通过ParameterMetaData获取参数的相关信息。但在运行过程中遇到了java.sql.SQLException: Parametermetadata not available for the given statement的错误。

灵活的传入sql语句，和sql语句的参数

报错：java.sql.SQLException: Parameter metadata not available for the given statement

原因不明

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.Date;
import java.sql.ParameterMetaData;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class ParameterMetaTest {
	
	
	public static void main(String[] args) throws SQLException{
		String sql = "select name,birthday from user where name =? and birthday<? and money>?";
		Object[] params = new Object[]{"list", new Date(System.currentTimeMillis()), 100f};
		ParameterMetaTest.read(sql,params);
	}
	
	
	//灵活的传入语句和参数
	public static void read(String sql, Object[] params) throws SQLException{
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		try {
			conn = JdbcUtils.getConnection();
			ps = conn.prepareStatement(sql);
			
			//可用于获取关于 PreparedStatement 对象中每个参数标记的类型和属性信息的对象
			ParameterMetaData pmd = ps.getParameterMetaData();
			int count = pmd.getParameterCount();
			
			for(int i=1; i<=count; i++){
				System.out.println(pmd.getParameterClassName(i));
				System.out.println(pmd.getParameterType(i));
				System.out.println(pmd.getParameterTypeName(i));
				ps.setObject(i, params[i-1]);
			}
			
			rs = ps.executeQuery();
			while(rs.next()){
				System.out.println(rs.getObject("name"));
				System.out.println(rs.getObject("birthday"));
			}
			
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			JdbcUtils.free(rs, ps, conn);
		}
	}
	
	
}