我在sql中插入了一列,其中的null值來自java.while取回它不與null.i同時使用string.length()進行檢查但是當我在System .OUT。該值顯示爲空(只是空)。當我檢查它與條件它不進入循環。java中的sql檢索值爲null
String id ="1234";
String name="pratap";
String gender=null;
String email=null;
String service="GOOGLE";
log.info(id+name+gender+email) //output is 1234pratapnullnull
String insert = "INSERT INTO oauthuser VALUES('"+id+"','"+name+"','"+gender+"','"+email+"','"+service"')";
在檢索
query ="Select * FROM oauthuser where id="+"'"+id+"'";
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection (dbUrl);
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
while(rs.next())
{
id=rs.getString(1);
name=rs.getString(2);
gender=rs.getString(3);
email=rs.getString(4);
service_provider_name=rs.getString(5);
System.out.println(gender+email+name);//output is nullnullpratap
}
if(gender!="male" && gender!="female")
System.out.println("it is printing");
if(gender==null)
System.out.println("it is not printing");
con.close();
向我們顯示代碼。 – NPE
把代碼插入並選擇 –
我們不能猜測什麼是問題,直到你告訴我們你是如何實現它 – giorashc