mysql-connector-java error Variable 'character_set_results' can't be set to the value of 'NULL'

[shiyuhang0]

Bug Report

when i use mysql-connector-java to connect to tidb.
it occurs java.sql.SQLSyntaxErrorException: Variable 'character_set_results' can't be set to the value of 'NULL'

• tidb version: build after this commit 77730b6
• mysql-connector-java: 5.1.44 or 8.0.26. I guess other version may has the same problem

public class DBHelper {

  public static final String url = "jdbc:mysql://address=(protocol=tcp)(host=$host)(port=4000)/?user=root&password=&useSSL=false";
  public static final String name = "com.mysql.jdbc.Driver";

  public Connection conn = null;

  public DBHelper() {
    try {
      Class.forName(name);
      conn = DriverManager.getConnection(url);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  public static void main(String[] args) {
    DBHelper helper = new DBHelper();
  }


pom:
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.26</version>
  </dependency>

[Defined2014]

@morgo Seems jdbc depends on this feature, we should revert #32879