Exception in thread “main“ com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException:

博客指出常见问题是SQL语句写错。这反映了在信息技术领域,SQL语句书写正确性的重要性,错误的语句可能导致数据操作异常等问题。

一般是sql语句写错了

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown database 'mydb' at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62) at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499) at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:483) at com.mysql.jdbc.Util.handleNewInstance(Util.java:404) at com.mysql.jdbc.Util.getInstance(Util.java:387) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:939) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3878) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3814) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:871) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1694) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1215) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2255) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2286) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2085) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44) at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62) at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499) at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:483) at com.mysql.jdbc.Util.handleNewInstance(Util.java:404) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327) at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:613) at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:199) at JDBCtest.DBUtil.getConnection(DBUtil.java:18) at JDBCtest.CreateDatabaseDemo.main(CreateDatabaseDemo.java:12) Exception in thread "main" java.lang.RuntimeException: java.lang.NullPointerException: Cannot invoke "java.sql.Connection.createStatement()" because "conn" is null at JDBCtest.CreateDatabaseDemo.main(CreateDatabaseDemo.java:20) Caused by: java.lang.NullPointerException: Cannot invoke "java.sql.Connection.createStatement()" because "conn" is null at JDBCtest.CreateDatabaseDemo.main(CreateDatabaseDemo.java:16)
最新发布
12-06
Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '//分别对应接口方法,对应的实体类 insert into user(name ,pas' at line 1 ### The error may exist in mappers/UserMapper.xml ### The error may involve mapper.UserMapper.addUser-Inline ### The error occurred while setting parameters ### SQL: //分别对应接口方法,对应的实体类 insert into user(name ,password,age,address) values (?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '//分别对应接口方法,对应的实体类 insert into user(name ,pas' at line 1 at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:196) at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:181) at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62) at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:145) at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:86) at com.sun.proxy.$Proxy4.addUser(Unknown Source) at UserTest.main(UserTest.java:27) Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '//分别对应接口方法,对应的实体类 insert into user(name ,pas' at line 1 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) at com.mysql.jdbc.Util.getInstance(Util.java:408) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2501) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858) at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1197) at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:47) at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74) at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50) at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117) at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:194) ... 6 more
10-19
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