如何使用Java执行多个SQL语句？

我有一个批处理程序，使用JDBC调用数据库。 我正在以“ID”作为主键发送一批100个信息

我想对数据库进行一次调用，然后在关闭连接之前执行多个SQL语句

我张贴部分代码以供参考

        //  Database credentials
        String USER = username;
        String PASS = password;

        Connection connec = null;
        Statement stmt = null;

        //STEP 2: Register JDBC driver
        Class.forName("com.mysql.jdbc.Driver");

        //STEP 3: Open a connection
        System.out.println("Connecting to a selected database...");
        connec = DriverManager.getConnection(DB_URL, USER, PASS);
        System.out.println("Connected database successfully...");

        //STEP 4: Execute a query
        System.out.println("Creating statement...");
        stmt = connec.createStatement();

        // Step 2: To update the database with the new count and the netppe values.

        // Step to know whether the ID is present or not in the database
        for(int i=0;i<identities.length;i++){
        String booleanString = "SELECT 1 FROM cgm_counters WHERE id = "+identities[i];

stmt.execute(booleanString);  
        ResultSet resultSet = stmt.getResultSet(); //result set for records  
        boolean recordFound = resultSet.next(); 
        ResultSet rs = null;
// Retrieve the 'netppe' information.
        if(recordFound){

            String sql =  "SELECT * FROM cgm_counters WHERE id="+identities[i];
            rs = stmt.executeQuery(sql);
            while(rs.next()){
                 //Retrieve by column name
                 double net_ppe  = rs.getDouble("spend");
                 System.out.println("The value of the netppe :"+net_ppe);
            }

}// end of 'If' statement

如何执行所有语句而不必关闭每个ID的连接？

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JDBC和SQL的新特性。非常感谢您的帮助。

好的，您的代码有很多问题。首先

//STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

您必须传递驱动程序实现，而不是接口本身；但好消息是，从JDBC4.0开始，这段代码就不再需要了。它已经扫描了你的类路径来为你定位驱动程序

其次，并不是每次查询都会关闭连接。代码中没有任何地方可以调用

connec.close（）

。JDBC也不会为您关闭连接

第三，您不需要对嵌套for循环执行此操作！那是个糟糕的主意。您对SQL查询和JDBC的概念需要进一步完善。您可以简单地执行以下操作：

for(int i=0;i<identities.length;i++) {
    String sql =  "SELECT * FROM cgm_counters WHERE id="+identities[i];
    ResultSet rs = stmt.executeQuery(sql);
    while(rs.next()){
        //Retrieve by column name
        double net_ppe  = rs.getDouble("spend");
        System.out.println("The value of the netppe :"+net_ppe);
    }
}

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for（int i=0；iwhy您需要关闭每个id的连接？您是否已经拥有不关闭连接的代码？@eis删除了'rs.close（）'语句，如果我不关闭连接并执行多个语句，相同的步骤是否有效？@user3188390关闭结果集与关闭数据库连接有什么关系？我将执行并标记，感谢您的建议和帮助。希望如果我确实有一些问题，我会在需要时获得帮助。
for(int i=0;i<identities.length;i++) {
    String sql =  "SELECT * FROM cgm_counters WHERE id="+identities[i];
    ResultSet rs = stmt.executeQuery(sql);
    while(rs.next()){
        //Retrieve by column name
        double net_ppe  = rs.getDouble("spend");
        System.out.println("The value of the netppe :"+net_ppe);
    }
}

String batch = "(";
for (int i = 0; i < identities.length;i++) {
    if (i < identities.length() - 1) 
        batch += "?, ";
    else 
        batch += "?)"
}

String sql =  "SELECT * FROM cgm_counters WHERE id in " + batch;
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()) {
    double net_ppe  = rs.getDouble("spend");
    System.out.println("The value of the netppe :"+net_ppe);
}