JDBC高级用法
1、批处理的使用：同时执行多个sql语句。可以用事务进行管理。用法参考代码：
import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; public class BatchDemo { public static void main(String[] args) { final String driver="com.mysql.jdbc.Driver"; try { Class.forName(driver); Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/sh","sh","123456"); Statement stmt=conn.createStatement(); //关闭自动提交 默认自动提交事务，后续代码使用手动添加事务进行处理 conn.setAutoCommit(false); //把以下三个insert语句作为一个批处理 stmt.addBatch("insert into employee values(161,'李',27,15000,'欧洲',101,105)"); stmt.addBatch("insert into employee values(162,'李',27,15000,'欧洲',101,105)"); stmt.addBatch("insert into employee values(163,'李',27,15000,'欧洲',101,105)"); //执行批处理，接收每条语句的执行结果 result数组中会存在一组0和1 int[] result=stmt.executeBatch(); for(int i:result){ System.out.println(i); } //提交事务 conn.commit(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } } 2、元数据 MetaData：描述数据库中的一些数据。1）DataBase MetaData：数据库的元数据。用法参考代码：
import java.sql.Connection; import java.sql.DatabaseMetaData; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; public class MetadataDemo { public static void main(String[] args) { final String driver="com.mysql.jdbc.Driver"; try { Class.forName(driver); Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/sh","sh","123456"); //数据的元数据：存放数据库的信息或者DBMS的信息 DatabaseMetaData dameta=conn.getMetaData(); System.out.println("驱动的名字"+dameta.getDriverName()); System.out.println("驱动的主版本"+dameta.getDatabaseMajorVersion()); System.out.println("驱动的小版本"+dameta.getDatabaseMinorVersion()); ResultSet rs=dameta.getTables(null, null, "employee", new String[] {"TABLE"}); //rs 结果集里每一列代表返回表中不同的信息 while(rs.next()){ System.out.println(rs.getString(1)); System.out.println(rs.getString(2)); System.out.println(rs.getString(3));//返回表名 System.out.println(rs.getString(4)); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } } 其中getTables返回的列包含以下数据： TABLE_CAT String => table catalog (may be null) TABLE_SCHEM String => table schema (may be null) TABLE_NAME String => table name TABLE_TYPE String => table type. Typical types are "TABLE", "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM". REMARKS String => explanatory comment on the table TYPE_CAT String => the types catalog (may be null) TYPE_SCHEM String => the types schema (may be null) TYPE_NAME String => type name (may be null) SELF_REFERENCING_COL_NAME String => name of the designated "identifier" column of a typed table (may be null) REF_GENERATION String => specifies how values in SELF_REFERENCING_COL_NAME are created. Values are "SYSTEM", "USER", "DERIVED". (may be null)2）ResultBase MetaData：结果集的元数据。用法参考代码：
import java.sql.Connection; import java.sql.DatabaseMetaData; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; public class MetadataDemo { public static void main(String[] args) { final String driver="com.mysql.jdbc.Driver"; try { Class.forName(driver); Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/sh","sh","123456"); //结果集的元数据 Statement stmt=conn.createStatement(); ResultSet rs1=stmt.executeQuery("select * from employee"); //获取结果集的元数据 ResultSetMetaData rsMeta=rs1.getMetaData(); System.out.println(rsMeta.getColumnCount());//返回结果集列数 System.out.println(rsMeta.getColumnName(3));//返回结果集第三列的列名 System.out.println(rsMeta.getTableName(2));//返回结果集第2列的表名 } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } }
