day48-JDBC和连接池04-2( 三 ) _生活百科

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3.单行单列

package li.jdbc.datasource;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.handlers.ScalarHandler;import org.junit.Test;import java.sql.Connection;public class DBUtils_USE {//演示DBUtils+druid完成-查询结果是单行单列的情况-返回的就是Object@Testpublic void testScalar() throws Exception {//Scalar 单一值//获取连接Connection connection = JDBCUtilsByDruid.getConnection();//创建QueryRunner对象QueryRunner queryRunner = new QueryRunner();//执行相关方法，返回单行单列String sql = "Select name from actor where id =?";//因为返回的是一个对象 ， 因此使用的 Handler是 ScalarHandlerObject obj = queryRunner.query(connection, sql, new ScalarHandler(), 1);System.out.println(obj);//释放资源JDBCUtilsByDruid.close(null,null,connection);}}

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10.5.6ApDBUtilsDML使用DBUtils+数据库连接池（德鲁伊）方式，完成对表actor的DML(update,insert,delete)操作

package li.jdbc.datasource;import org.apache.commons.dbutils.QueryRunner;import org.junit.Test;import java.sql.Connection;import java.sql.SQLException;public class DBUtils_USE {//演示DBUtils+druid完成 dml操作@Testpublic void testDML() throws SQLException {//获取连接Connection connection = JDBCUtilsByDruid.getConnection();//创建QueryRunner对象QueryRunner queryRunner = new QueryRunner();//这里组织sql完成update，insert，delete//String sql = "update actor set name =? where id =?";//String sql = "insert into actor values (null,?,?,?,?)";String sql = "delete from actor where id =?";/*** 1.执行dml的操作是queryRunner.update()* 2.返回的值是受影响的行数,如果返回的是0，代表sql执行失败 或者 执行成功但是表没受影响*///int affectedRow = queryRunner.update(connection, sql,"黎明","女","1999-10-09","123");int affectedRow = queryRunner.update(connection, sql,1000);System.out.println(affectedRow > 0 ? "执行成功" : "执行没有影响到表");//释放资源JDBCUtilsByDruid.close(null, null, connection);}}

10.6表和JavaBean的类型映射关系