JDBC中如何在一个数据库上同时执行多个SQL命令？

Java数据库连接也称为 JDBC，是Java中的应用程序编程接口，用于在Java应用程序和数据库之间建立连接。 JDBC 命令可用于从Java应用程序执行 SQL 操作。演示使用 JDBC 的 addBatch() 和 executeBatch() 命令在数据库上同时执行多个 SQL 命令。

The addBatch() command is used to queue the SQL statements and executeBatch() command is used to execute the queued SQL statements all at once. In order to use SQL statements in the Java application, ”java.sql” package needs to be imported in the beginning of the Java application. The Java application is connected to the database using the getConnection() method of DriverManager class. The getConnection() method takes three parameters URLs, username and password.

目标：演示两个示例，其中一个使用Statement 接口，另一个使用PreparedStatement接口。 PreparedStatement 的性能优于 Statement 接口。 Statement 接口可用于执行静态 SQL 查询，而 PreparedStatement 接口可用于多次执行动态 SQL 查询。

示例 1：使用语句接口

在此示例中，导入了Java.sql 包类和接口。 Statement 接口用于执行 sql 语句。该表是创建 sql 语句以及记录插入 sql 语句，使用 addBatch() 命令添加到批处理中。当所有语句都被批处理时，executeBatch() 命令被执行，它同时运行所有批处理查询。 sql 语句可能会抛出 SQL 异常，必须在 try catch 块中处理这些异常，以避免程序突然终止。创建表并插入记录后，要查看表中的数据，执行选择查询。通过执行选择查询获得的结果存储在 ResultSet 游标中。使用 next() 方法迭代光标，并在屏幕上显示记录。

实现：使用标准接口

Java

// Step 1: Create a database
// SQL database imported
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
 
public class BatchCommand {
 
    // Main driver method
    public static void main(String args[])
    {
 
        // Try block to check if exception occurs
        try {
 
            // Step 2: Loading driver class
            // Using forName()
            Class.forName("oracle.jdbc.OracleDriver");
 
            // Step 3: Create connection object
            Connection con = DriverManager.getConnection(
                "jdbc:oracle:thin:@localhost:1521:xe",
                "username", "password");
            Statement s = con.createStatement();
           
            // Step 4: Create a statement / create table
            String sql1
                = "CREATE TABLE STUDENT(STUDENTID VARCHAR2(10) PRIMARY KEY,NAME VARCHAR2(20),DEPARTMENT VARCHAR2(10))";
 
            // Step 5: Process a query
            // Insert records in the table
            String sql2
                = "INSERT INTO STUDENT VALUES('S101','JEAN','CSE')";
            String sql3
                = "INSERT INTO STUDENT VALUES('S102','ANA','CSE')";
            String sql4
                = "INSERT INTO STUDENT VALUES('S103','ROBERT','ECE')";
            String sql5
                = "INSERT INTO STUDENT VALUES('S104','ALEX','IT')";
            String sql6
                = "INSERT INTO STUDENT VALUES('S105','DIANA','IT')";
            s.addBatch(sql1);
            s.addBatch(sql2);
            s.addBatch(sql3);
            s.addBatch(sql4);
            s.addBatch(sql5);
            s.addBatch(sql6);
 
            // Step 6: Process the results
            // execute the sql statements
            s.executeBatch();
            ResultSet rs
                = s.executeQuery("Select * from Student");
 
            // Print commands
            System.out.println(
                "StudentID\tName\t\tDepartment");
            System.out.println(
                "-------------------------------------------------------");
 
            // Condition to check pointer pointing
            while (rs.next()) {
                System.out.println(rs.getString(1) + "\t\t"
                                   + rs.getString(2)
                                   + "\t\t"
                                   + rs.getString(3));
            }
 
            // Step 7: Close the connection
            con.commit();
            con.close();
        }
 
        // Catch block to handle exceptions
        catch (Exception e) {
 
            // Print line number if exception occured
            System.out.println(e);
        }
    }
}

使用 addBatch() 方法在 executeBatch() 的参与下对数据库的 SQL 命令

Java

// Step 1: Importing database
// SQL database imported
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
 
public class BatchCommand {
 
    // Main driver method
    public static void main(String args[])
    {
 
        // Try block to handle if exception occurs
        try {
 
            // Step 2: loading driver class
            Class.forName("oracle.jdbc.OracleDriver");
 
            // Step 3: create connection object
            Connection con = DriverManager.getConnection(
                "jdbc:oracle:thin:@localhost:1521:xe",
                "username", "password");
            Statement s = con.createStatement();
 
            // Step 4: Create a statement
            // Create table
            String sql1
                = "CREATE TABLE STUDENT(STUDENTID VARCHAR2(10) PRIMARY KEY,NAME VARCHAR2(20),DEPARTMENT VARCHAR2(10))";
 
            // Step 5: Execute a query
            // Insert records in the table
            String sql2
                = "INSERT INTO STUDENT VALUES('S101','JEAN','CSE')";
            String sql3
                = "INSERT INTO STUDENT VALUES('S102','ANA','CSE')";
            String sql4
                = "INSERT INTO STUDENT VALUES('S103','ROBERT','ECE')";
            String sql5
                = "INSERT INTO STUDENT VALUES('S104','ALEX','IT')";
            String sql6
                = "INSERT INTO STUDENT VALUES('S105','DIANA','IT')";
            s.addBatch(sql1);
            s.addBatch(sql2);
            s.addBatch(sql3);
            s.addBatch(sql4);
            s.addBatch(sql5);
            s.addBatch(sql6);
 
            // Step 6: Process the statements
            // Create an int[] to hold returned values
            s.executeBatch();
            ResultSet rs
                = s.executeQuery("Select * from Student");
 
            // Print statements
            System.out.println(
                "StudentID\tName\t\tDepartment");
            System.out.println(
                "-------------------------------------------------------");
 
            // Condition check for pointer pointing which
            // record
            while (rs.next()) {
                System.out.println(rs.getString(1) + "\t\t"
                                   + rs.getString(2)
                                   + "\t\t"
                                   + rs.getString(3));
            }
 
            // Step 7: Close the connection
            con.commit();
            con.close();
        }
 
        // Catch block to handle exception
        catch (Exception e) {
 
            // Print line number where exception occured
            System.out.println(e);
        }
    }
}

输出

示例2：在本示例中，导入了Java.sql 包类和接口。 PreparedStatement 接口用于执行 SQL 语句。该表是使用 addBatch() 命令将创建 SQL 语句与记录插入 SQL 语句一起添加到批处理中。当所有语句都被批处理时，executeBatch() 命令被执行，它同时运行所有批处理查询。 sql 语句可能会抛出 SQL 异常，必须在 try-catch 块中处理这些异常，以避免程序突然终止。创建表并插入记录后，要查看表中的数据，执行选择查询。通过执行选择查询获得的结果存储在 ResultSet 游标中。使用 next() 方法迭代光标，并在屏幕上显示记录。与前面的示例不同，它需要来自用户的动态输入。因此，使用 PreparedStatement 具有性能优势。

代码实现

Java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.*;
public class AddBatchCommand {
    public static void main(String args[])
    {
        Scanner scan = new Scanner(System.in);
        try {
 
            // loading driver class
            Class.forName("oracle.jdbc.OracleDriver");
 
            // create connection object
            Connection con = DriverManager.getConnection(
                "jdbc:oracle:thin:@localhost:1521:xe",
                "username", "password");
 
            // create the table
            String sql1
                = "CREATE TABLE STUDENTS(STUDENTID VARCHAR2(10) PRIMARY KEY,NAME VARCHAR2(20),DEPARTMENT VARCHAR2(10))";
            PreparedStatement ps
                = con.prepareStatement(sql1);
            ps.execute(sql1);
 
            // inserting records
            String sql
                = "Insert into Students values(?,?,?)";
            PreparedStatement ps1
                = con.prepareStatement(sql);
            for (int i = 0; i < 3; i++) {
                System.out.println("Enter Student ID");
                String id = scan.nextLine();
                System.out.println("Enter Student Name");
                String name = scan.nextLine();
                System.out.println("Enter the Department");
                String dept = scan.nextLine();
                ps1.setString(1, id);
                ps1.setString(2, name);
                ps1.setString(3, dept);
                // adding to batch
                ps1.addBatch();
            }
            // executing the batch
            ps1.executeBatch();
           
            // viewing the table
            ResultSet rs
                = ps.executeQuery("Select * from Students");
            System.out.println(
                "StudentID\tName\t\tDepartment");
            System.out.println(
                "-------------------------------------------------------");
            while (rs.next()) {
                System.out.println(rs.getString(1) + "\t\t"
                                   + rs.getString(2)
                                   + "\t\t"
                                   + rs.getString(3));
            }
            con.commit();
            con.close();
        }
 
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：同时说明数据库上的多个 SQL 命令：