Com. mysql. jdbc. exceptions. jdbc4.MySQLSyntaxErrorException: Unknown column & #39 ;?????? & #39; in & #39; field list & #39;

Severe: Servlet. service () for servlet jsp threw exception
Com. mysql. jdbc. exceptions. jdbc4.MySQLSyntaxErrorException: Unknown column '?????? 'In' field list'
At sun. reflect. NativeConstructorAccessorImpl. newInstance0 (Native Method)
At sun. reflect. nativeconstruct%cessorimpl. newInstance (nativeconstruct%cessorimpl. java: 39)
At sun. reflect. delegatingconstruct%cessorimpl. newInstance (delegatingconstruct%cessorimpl. java: 27)
At java. lang. reflect. Constructor. newInstance (Constructor. java: 513)
At com. mysql. jdbc. Util. handleNewInstance (Util. java: 406)
At com. mysql. jdbc. Util. getInstance (Util. java: 381)
At com. mysql. jdbc. SQLError. createSQLException (SQLError. java: 1030)
At com. mysql. jdbc. SQLError. createSQLException (SQLError. java: 956)
At com. mysql. jdbc. MysqlIO. checkErrorPacket (MysqlIO. java: 3491)
At com. mysql. jdbc. MysqlIO. checkErrorPacket (MysqlIO. java: 3423)
At com. mysql. jdbc. MysqlIO. sendCommand (MysqlIO. java: 1936)
At com. mysql. jdbc. MysqlIO. sqlQueryDirect (MysqlIO. java: 2060)
At com.mysql.jdbc.ConnectionImpl.exe cSQL (ConnectionImpl. java: 2536)
At com.mysql.jdbc.StatementImpl.exe cuteUpdate (StatementImpl. java: 1564)
At com.mysql.jdbc.StatementImpl.exe cuteUpdate (StatementImpl. java: 1485)
At org. apache. jsp. insert_jsp. _ jspService (insert_jsp.java: 100)
At org. apache. jasper. runtime. HttpJspBase. service (HttpJspBase. java: 70)
At javax. servlet. http. HttpServlet. service (HttpServlet. java: 723)
At org. apache. jasper. servlet. JspServletWrapper. service (JspServletWrapper. java: 388)
At org. apache. jasper. servlet. JspServlet. serviceJspFile (JspServlet. java: 313)
At org. apache. jasper. servlet. JspServlet. service (JspServlet. java: 260)
At javax. servlet. http. HttpServlet. service (HttpServlet. java: 723)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 290)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. apache. catalina. core. StandardWrapperValve. invoke (StandardWrapperValve. java: 233)
At org. apache. catalina. core. StandardContextValve. invoke (StandardContextValve. java: 191)
At org. apache. catalina. core. StandardHostValve. invoke (StandardHostValve. java: 127)
At org. apache. catalina. valves. ErrorReportValve. invoke (ErrorReportValve. java: 103)
At org. apache. catalina. core. StandardEngineValve. invoke (StandardEngineValve. java: 109)
At org. apache. catalina. connector. CoyoteAdapter. service (CoyoteAdapter. java: 293)
At org. apache. coyote. http11.Http11NioProcessor. process (Http11NioProcessor. java: 891)
At org. apache. coyote. http11.Http11NioProtocol $ Http11ConnectionHandler. process (Http11NioProtocol. java: 750)
At org.apache.tomcat.util.net. NioEndpoint $ SocketProcessor. run (NioEndpoint. java: 2282)
At java. util. concurrent. ThreadPoolExecutor $ Worker. runTask (ThreadPoolExecutor. java: 886)
At java. util. concurrent. ThreadPoolExecutor $ Worker. run (ThreadPoolExecutor. java: 908)
At java. lang. Thread. run (Thread. java: 619)

 

------ Solution --------------------
This error is simple.
From this code, we can see that: String SQL = "INSERT INTO STUDENT VALUES (" + id + "," + name + ")";
If my id = 1, name = adf, then the combined string is
Insert into student values (1, adf) You can try to execute this SQL statement, and it will certainly report an error
The correct syntax should be insert into student values (1, 'fid'); -- the numeric type can be enclosed in single quotes.

So
It should be String SQL = "INSERT INTO STUDENT VALUES (" + id + ", '" + name + "')";
------ Solution --------------------
When you encounter this type of database statement, you can use
System. out. print (SQL); output your statements first, so that you can easily find out if there are any errors.