//JAVA，数据库以MySQL为例。

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

public class ColumnCount 
{
    public static void main(String[]args)
    {
        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection("JDBC:MYSQL://LocalHost:3306/building","root","123456");
            Statement stm = conn.createStatement();
            String sql = "select * from user";
            ResultSet rs = stm.executeQuery(sql);
            ResultSetMetaData rsmd = rs.getMetaData();
            int columnCount = rsmd.getColumnCount();
            System.out.println("MySQL的building数据库的user表一共有"+columnCount+"列。");
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
    }
}