Question

当我想从databaseMetaData获取表时，我收到此错误：

Exception in thread "main" java.sql.SQLException: Table name pattern can not be NULL or empty.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:545)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:513)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:505)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:479)
at com.mysql.cj.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:3836)
at FindUserTables.main(FindUserTables.java:14)
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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

这是我的代码，我的jdbc驱动程序是mysql-connector-java-6.0.5-bin.jar。发生了什么事？

import java.sql.*;
public class FindUserTables {
    public static void main(String[] args)
            throws SQLException, ClassNotFoundException {
        Class.forName("com.mysql.cj.jdbc.Driver");
        System.out.println("Driver loaded");
        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/javabook ?characterEncoding=utf8&useSSL=false&&serverTimezone=UTC", "root", "123456");
        System.out.println("Database connected");
        DatabaseMetaData dbMetaData = connection.getMetaData();
        ResultSet rsTables = dbMetaData.getTables(null, null, null,
                new String[] {"TABLE"});
        System.out.print("User tables: ");
        while (rsTables.next())
            System.out.print(rsTables.getString("TABLE_NAME") + " ");
        connection.close();
    }
}

Answer 1

https://dev.mysql.com/doc/connector-j/6.0/en/connector-j-properties-changed.html在“默认值已更改的属性：”

下说

nullNamePatternMatchesAll现在默认为false

因此，解决此问题的一种方法是将?nullNamePatternMatchesAll=true附加到连接字符串（如果?不是连接字符串中的第一个属性，则将&替换为ArrayAdapter<String> itemsAdapter = new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1, arrayList); holder.spinner.setAdapter(itemsAdapter); itemsAdapter.notifyDataSetChanged(); holder.spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { String selected = holder.spinner.getSelectedItem().toString(); System.out.println("selected = " + selected); } @Override public void onNothingSelected(AdapterView<?> parentView) { } });。

Answer 2

在您的JDBC URL中添加此

nullNamePatternMatchesAll=true

jdbc:mysql://<Host>/<DB>?nullNamePatternMatchesAll=true

Answer 3

您将null值传递给dbMetaData.getTables()，其中一个（最后一个）应该是表名模式（对所有人都尝试"%"）并且正如消息所示，它不能是null或空。

似乎可以根据（较旧的）source code进行配置，但我想你应该明确参数，以确定。

Answer 4

试试这个：

DatabaseMetaData dbMetaData = conn.getMetaData();
ResultSet rsTables = dbMetaData.getTables(null, null, "%", null);
while (rsTables .next()) {
  System.out.print(rsTables.getString(3) + " ");
}

java中的“表名模式不能为NULL或为空”

4 个答案: