[Mysql 查询语句]——查询字段

查询所有字段

    select  *  from  表名;

可以用 * 号代表所有字段

select * from vendors;
+---------+----------------+-----------------+-------------+------------+----------+--------------+
| vend_id | vend_name      | vend_address    | vend_city   | vend_state | vend_zip | vend_country |
+---------+----------------+-----------------+-------------+------------+----------+--------------+
|    1001 | Anvils R Us    | 123 Main Street | Southfield  | MI         | 48075    | USA          |
|    1002 | LT Supplies    | 500 Park Street | Anytown     | OH         | 44333    | USA          |
|    1003 | ACME           | 555 High Street | Los Angeles | CA         | 90046    | USA          |
|    1004 | Furball Inc.   | 1000 5th Avenue | New York    | NY         | 11111    | USA          |
|    1005 | Jet Set        | 42 Galaxy Road  | London      | NULL       | N16 6PS  | England      |
|    1006 | Jouets Et Ours | 1 Rue Amusement | Paris       | NULL       | 45678    | France       |
+---------+----------------+-----------------+-------------+------------+----------+--------------+

查询指定字段

   select 字段名1,字段名2 from 表名;

   select 字段名1 as 别名1, 字段名2 as 别名2 from 表名;

可以只指定查询想查询的字段，改变顺序和为这些字段定义别名输出都可以

select vend_id,vend_city,vend_name from vendors;
+---------+-------------+----------------+
| vend_id | vend_city   | vend_name      |
+---------+-------------+----------------+
|    1001 | Southfield  | Anvils R Us    |
|    1002 | Anytown     | LT Supplies    |
|    1003 | Los Angeles | ACME           |
|    1004 | New York    | Furball Inc.   |
|    1005 | London      | Jet Set        |
|    1006 | Paris       | Jouets Et Ours |
+---------+-------------+----------------+

select vend_id as 供货商ID,vend_name as 供货商名,vend_city as 供货商城市 from vendors;
+-------------+----------------+-----------------+
| 供货商ID    | 供货商名       | 供货商城市      |
+-------------+----------------+-----------------+
|        1001 | Anvils R Us    | Southfield      |
|        1002 | LT Supplies    | Anytown         |
|        1003 | ACME           | Los Angeles     |
|        1004 | Furball Inc.   | New York        |
|        1005 | Jet Set        | London          |
|        1006 | Jouets Et Ours | Paris           |
+-------------+----------------+-----------------+