从java.sql.ResultSet中检索列名

Question

有java.sql.ResultSet没有办法String通过使用列的索引获取列的名称？我查看了API文档但我找不到任何东西.

Answer 1

您可以从ResultSet元数据中获取此信息.请参见ResultSetMetaData

例如

 ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
 ResultSetMetaData rsmd = rs.getMetaData();
 String name = rsmd.getColumnName(1);

你可以从那里得到列名.如果你这样做

select x as y from table

然后rsmd.getColumnLabel()也会得到检索到的标签名称.

Answer 2

除了上面的答案,如果您正在使用动态查询并且您想要列名但不知道有多少列,则可以使用ResultSetMetaData对象首先获取列数,然后循环它们.

修改Brian的代码:

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();

// The column count starts from 1
for (int i = 1; i <= columnCount; i++ ) {
  String name = rsmd.getColumnName(i);
  // Do stuff with name
}

Answer 3

您可以使用ResultSetMetaData(http://java.sun.com/javase/6/docs/api/java/sql/ResultSetMetaData.html)对象,如下所示:

ResultSet rs = stmt.executeQuery("SELECT * FROM table");
ResultSetMetaData rsmd = rs.getMetaData();
String firstColumnName = rsmd.getColumnName(1);

Answer 4

这个问题很老,以前的答案也是正确的.但是当我发现这个话题时我正在寻找的就像这个解决方案.希望它可以帮助某人.

// Loading required libraries    
import java.util.*;
import java.sql.*;

public class MySQLExample {
  public void run(String sql) {
    // JDBC driver name and database URL
    String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    String DB_URL = "jdbc:mysql://localhost/demo";

    // Database credentials
    String USER = "someuser"; // Fake of course.
    String PASS = "somepass"; // This too!

    Statement stmt = null;
    ResultSet rs = null;
    Connection conn = null;
    Vector<String> columnNames = new Vector<String>();

    try {
      // Register JDBC driver
      Class.forName(JDBC_DRIVER);

      // Open a connection
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      // Execute SQL query
      stmt = conn.createStatement();
      rs = stmt.executeQuery(sql);
      if (rs != null) {
        ResultSetMetaData columns = rs.getMetaData();
        int i = 0;
        while (i < columns.getColumnCount()) {
          i++;
          System.out.print(columns.getColumnName(i) + "\t");
          columnNames.add(columns.getColumnName(i));
        }
        System.out.print("\n");

        while (rs.next()) {
          for (i = 0; i < columnNames.size(); i++) {
            System.out.print(rs.getString(columnNames.get(i))
                + "\t");

          }
          System.out.print("\n");
        }

      }
    } catch (Exception e) {
      System.out.println("Exception: " + e.toString());
    }

    finally {
      try {
        if (rs != null) {
          rs.close();
        }
        if (stmt != null) {
          stmt.close();
        }
        if (conn != null) {
          conn.close();
        }
      } catch (Exception mysqlEx) {
        System.out.println(mysqlEx.toString());
      }

    }
  }
}

Answer 5

SQLite 3

使用getMetaData（）;

DatabaseMetaData md = conn.getMetaData();
ResultSet rset = md.getColumns(null, null, "your_table_name", null);

System.out.println("your_table_name");
while (rset.next())
{
    System.out.println("\t" + rset.getString(4));
}

编辑：这也适用于PostgreSQL