Netbeans java应用程序-在MySql数据库上执行查询

Question

在我正在工作的项目中，我需要执行搜索SQL查询，即Java Netbeans中的通配符。我能够执行简单的查询，如

    String driver = "jdbc:mysql://localhost/techo";
    String un = "root";
    String pw = "root";
    String empid = id.getText();
    try{
        Connection con = DriverManager.getConnection(driver,un,pw);
        Statement stm = con.createStatement();
        ResultSet rs = stm.executeQuery("select*from employees where empid ="+empid+"");
        while(rs.next())
        {
            String name = rs.getString("name");
            String salary = rs.getString("salary");
            name1.setText(name);
            salary1.setText(salary);
        }
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null,e);
    }

这完全可以正常工作。但现在我想使用这个MySql查询

Mysql>select * from employes where empid like "123%";

而不是

Mysql>select * from employes where empid =123;

我已经试过了

    String driver = "jdbc:mysql://localhost/techo";
    String un = "root";
    String pw = "root";
    String empid = id.getText();
    try{
        Connection con = DriverManager.getConnection(driver,un,pw);
        Statement stm = con.createStatement();
        ResultSet rs = stm.executeQuery("select*from employees where empid like "+empid%+"");
        while(rs.next())
        {
            String id = rs.getString("EmpId");
            String name = rs.getString("name");
            String salary = rs.getString("salary");
            area.setText(id +"    "+name+"    "+salary+"    "+ "n");
        }
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null,e);
    }

您可以看到，在第8行中，我插入了通配符(%)，但这不起作用。我怎么解决这个问题?

Answer 1

您的通配符放错了位置。应该是:

        ResultSet rs = stm.executeQuery("select*from employees where empid like "+empid+"%");

在这种情况下，%字符将被视为通配符。

如果你想搜索%字符本身，你必须按照mysql的转义规则转义它:

        ResultSet rs = stm.executeQuery("select*from employees where empid like ""+empid+"%%"");

要特别注意引号