Java我如何知道表列的值是否是自动递增的?
该ResultSetMetaData.isAutoIncrement()方法可以告诉我们是否自动对列值进行编号。true当列是自动递增的列时,此方法返回,否则返回false。请参见下面的示例,在该示例中我们检查第一列(id)是否为自动增量列。
package org.nhooo.example.jdbc; import java.sql.*; public class IsAutoIncrementExample { private static final String URL = "jdbc:mysql://localhost/nhooo"; private static final String USERNAME = "root"; private static final String PASSWORD = ""; public static void main(String[] args) { try (Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD)) { Statement statement = connection.createStatement(); ResultSet resultSet = statement.executeQuery( "SELECT id, username, order_date FROM orders"); //ResultSetMetaData是所有元数据相关的地方 //存储结果集的信息。 ResultSetMetaData metadata = resultSet.getMetaData(); if (metadata.isAutoIncrement(1)) { System.out.println("Column `id` is an auto-increment column."); } } catch (SQLException e) { e.printStackTrace(); } } }
Maven依赖
<!-- https://search.maven.org/remotecontent?filepath=mysql/mysql-connector-java/8.0.17/mysql-connector-java-8.0.17.jar --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.17</version> </dependency>