java - 我如何使用 java 在 mysql 数据库中根据日期差异(来自另一个表的日期和当前日期)将表中的特定标志更新为 'Y'

Question

有两个表 1.Transcation_Details 和 2.Flags 都定义为 1. Cust_ID(主键), last_Login_date; 2. Cust_ID(主键), emailFlag, OfflineFlag, InactiveFlag;

在java程序中:

diff = current_date - last_Login_date
if (diff > 30 and diff <60) set emailFlag as 'Y'
else if( diff > 60 and diff < 120) set OfflineFlag as 'Y'
else if(diff > 120) set InactiveFlag as 'Y'

这段代码可以吗？我可以做得更好吗？

public class SetFlags {
//to edit and feed the date from the temporary table to the fact table
static String sql, sql1, tableName;
private static PreparedStatement pstmt = null, pstmt1 = null;
private static Statement stmt = null;
private static ResultSet resultset = null;
private static ResultSet resultset2 = null;
static SimpleDateFormat myFormat = new SimpleDateFormat("yyyy-MM-dd");

public static int differenceOfDays(Date d1, Date d2) {
    int daysdiff = 0;
    long diff = d2.getTime() - d1.getTime();
    long diffDays = diff / (24 * 60 * 60 * 1000) + 1;
    daysdiff = (int) diffDays;
    return daysdiff;
}

public static void setFlag(String query) throws SQLException {
    //String query = "UPDATE Flags SET f.EmailFlag = 'Y' from Flags f, Transaction_Details t where f.Cust_ID = t.Cust_ID";
    stmt = ManageDBResource.conn.createStatement();
            //Statement(query, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
    int result = stmt.executeUpdate(query);

    if(result == 1) {
        System.out.println("Flag Set");
    }
    else {
        System.err.println("error in updating Flag");
    }

}

public static void setFlags() throws SQLException {
    sql = "Select * From Transaction_Details";
    sql1 = "Select * From Customer_Info";
    ManageDBResource.createConnectionToDB();
    pstmt = ManageDBResource.conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
    pstmt1 = ManageDBResource.conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
    resultset = pstmt.executeQuery();
    resultset2 = pstmt.executeQuery(); 

    while(resultset.next()) {

        java.util.Date last_Login_Date = resultset.getDate("LAST_TIME_LOGIN_DATE");
        java.util.Date currentDate = new java.util.Date();

        int diff = differenceOfDays(last_Login_Date, currentDate);

        if(diff > 30 && diff < 60) {
            setFlag("UPDATE Flags SET EmailFlag = 'Y' from Flags where Cust_ID = " + Integer.toString(resultset.getInt("Cust_ID")));
        }
        else if(diff > 60 && diff < 120) {
            setFlag("UPDATE Flags SET OfflineFlag = 'Y' from Flags where Cust_ID = " + Integer.toString(resultset.getInt("Cust_ID")));
        }
        else if(diff > 120) {
            setFlag("UPDATE Flags SET InactiveFlag = 'Y' from Flags where Cust_ID = " + Integer.toString(resultset.getInt("Cust_ID")));
        }

    }
}

如何使用 PreparedStatement 对象编写和执行查询以更新 java 中的标志。

请提出您喜欢的任何方式。

Answer 1

您可以对所有情况使用单个更新，例如:

  UPDATE Flags f 
  INNER JOIN Transcation_Details t on t.Cust_ID = f.Cust_ID
        SET f.EmailFlag = case when datediff(curdate(), t.last_login_date) > 30 
                and   datediff(curdate(), t.last_login_date) <60  then 'Y' else f.EmailFlag end 
     , f.OfflineFlag = case when datediff(curdate(), t.last_login_date) > 60 
                and   datediff(curdate(), t.last_login_date) <120  then 'Y' else f.OfflineFlag end 
     , f.InactiveFlag = case when datediff(curdate(), t.last_login_date) > 12  then 'Y' else f.InactiveFlag end 
    where  f.cust_ID = :your_cust_id