运行错误如下

java.sql.SQLException: Can not call getNString() when field's charset isn't UTF-8

at com.mysql.cj.jdbc.result.ResultSetImpl.getNString(ResultSetImpl.java:1043)

at com.mysql.cj.jdbc.result.ResultSetImpl.getNString(ResultSetImpl.java:1050)

at com.imooc.jdbc.dome1.JDBCDemo1.demo1(JDBCDemo1.java:28)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)

at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)

at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)

at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)

at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)

at org.junit.runners.ParentRunner.run(ParentRunner.java:413)

at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)

at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:542)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:770)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)

muke_xinke 2020-08-27

源自：JDBC入门 2-1 JDBC的入门

收起

2回答

好帮手慕小脸 2020-08-28 17:29:05

同学你好，建议同学按照如下方式重新创建表再试试：

CREATE TABLE `user2` (
  `uid` INT NOT NULL AUTO_INCREMENT,
  `username` VARCHAR(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `password` VARCHAR(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `name` VARCHAR(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  PRIMARY KEY (`uid`)
) ENGINE=INNODB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8

祝学习愉快~

收起回答

好帮手慕阿慧 2020-08-27 18:34:30

同学你好，当字段的字符集不是utf-8时，无法调用getnstring()方法。同学需要将数据库表中所有字段都设置成utf-8，在数据库中执行命令：

alter table  表名 convert to character set utf8

如果我的回答解决了你的疑惑，请采纳！祝学习愉快！

收起回答

提问者 muke_xinke #1

这样吗 mysql> use jdbctest; Database changed mysql> alter table user convert to character set utf8; Query OK, 0 rows affected, 1 warning (0.01 sec) Records: 0 Duplicates: 0 Warnings: 1 mysql>

2020-08-27 18:40:00
好帮手慕阿慧回复提问者 muke_xinke #2

同学你好，是这样的。祝学习愉快~

2020-08-27 18:56:38
提问者 muke_xinke 回复好帮手慕阿慧 #3

改完还是这样是咋回事呢提示的还是这个

2020-08-27 19:03:13