每天走走

SELECT column1, column2  FROM table1, table2    WHERE [ conditions ]    GROUP BY column1, column2    HAVING [ conditions ]    ORDER BY column1, column2(1)交叉连接 - CROSS JOIN FROM table1 CROSS JOIN table...

1.select语句   SELECT column1, column2, columnN FROM table_name;, column2, columnN FROM table_name; WHERE AGE >= 25 AND SALARY >= 65000;>= 25 AND SALARY >= 65000; <strong>WHERE ...