Question

jsp 如何判定查询的sql数据库里面是否有这个值

<%
String url = "jdbc:sqlserver://192.168.11.251:1433;databaseName=test5;user=sa;password=123";
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
con = DriverManager.getConnection(url);
String SQL = "select * from [2017$] where company like "+"'"+no+name+"'";
stmt = con.createStatement();
rs = stmt.executeQuery(SQL);
while (rs.next())
{
%>

Answer 1

示例：
JSP 页面中：<input name = "username">
后台 ：String sql = "select * from user where username =?";//从用户表中查询指定用户名的数据
取得文本框中的值:String name = requset.getParameter("username");
然后取得connection对象 conn
Preparestatement pstmt = conn.preparestatement();
pstmt.setString(1,name);//拼接sql语句成为:select * from user where username =（name的值）;
最后执行sql语句

追问

这个问题已经解决了 但是我想问一下 =rs.getString("表首列")几个能相加吗？