• 关键字(keyword)
      作为SQL组成部分的字段，关键字不能作为表或者列的名字。

    使用SELECT索引数据，必须至少给出两条信息，

    解释：使用SELECT 语句从 Products 表中检索一个名为prod_name 的列，FROM 关键字从指定的标名索引。

    1. mysql> SELECT prod_name FROM Products;
    2. +---------------------+
    3. | prod_name           |
    4. +---------------------+
    5. | Fish bean bag toy   |
    6. | Bird bean bag toy   |
    7. | Rabbit bean bag toy |
    8. | 8 inch teddy bear   |
    9. | 12 inch teddy bear  |
    10. | 18 inch teddy bear  |
    11. | Raggedy Ann         |
    12. | King doll           |
    13. +---------------------+
    • SQL语句分成多好容易阅读与调试，如果语句较长
    • SQL语句必须以(;)结束。
    • SQL语句不区分大小写，除了表名，跟值以外，SQL关键字使用大写，便于阅读

    与索引单列对比，唯一的不同是必须，在SELECT 关键字后给出多个列名，列名直接用， 隔开，最后一列不需要。

    解释：使用SELECT 从表Products 中选择数据，指定3个列名，prod_id, prod_name, prod_price

    1. mysql> SELECT prod_id, prod_name, prod_price FROM Products;
    2. +---------+---------------------+------------+
    3. | prod_id | prod_name           | prod_price |
    4. +---------+---------------------+------------+
    5. | BNBG01  | Fish bean bag toy   |       3.49 |
    6. | BNBG02  | Bird bean bag toy   |       3.49 |
    7. | BNBG03  | Rabbit bean bag toy |       3.49 |
    8. | BR01    | 8 inch teddy bear   |       5.99 |
    9. | BR02    | 12 inch teddy bear  |       8.99 |
    10. | BR03    | 18 inch teddy bear  |      11.99 |
    11. | RGAN01  | Raggedy Ann         |       4.99 |
    12. | RYL01   | King doll           |       9.49 |
    14. 9 rows in set (0.01 sec)

    使用通配符 * 表示返回表中所有的列

    1. mysql> SELECT * FROM Products;
    2. +---------+---------+---------------------+------------+-----------------------------------------------------------------------+
    3. | prod_id | vend_id | prod_name           | prod_price | prod_desc                                                             |
    4. +---------+---------+---------------------+------------+-----------------------------------------------------------------------+
    5. | BNBG01  | DLL01   | Fish bean bag toy   |       3.49 | Fish bean bag toy, complete with bean bag worms with which to feed it |
    6. | BNBG02  | DLL01   | Bird bean bag toy   |       3.49 | Bird bean bag toy, eggs are not included                              |
    7. | BNBG03  | DLL01   | Rabbit bean bag toy |       3.49 | Rabbit bean bag toy, comes with bean bag carrots                      |
    8. | BR01    | BRS01   | 8 inch teddy bear   |       5.99 | 8 inch teddy bear, comes with cap and jacket                          |
    9. | BR02    | BRS01   | 12 inch teddy bear  |       8.99 | 12 inch teddy bear, comes with cap and jacket                         |
    10. | BR03    | BRS01   | 18 inch teddy bear  |      11.99 | 18 inch teddy bear, comes with cap and jacket                         |
    11. | RGAN01  | DLL01   | Raggedy Ann         |       4.99 | 18 inch Raggedy Ann doll                                              |
    12. | RYL01   | FNG01   | King doll           |       9.49 | 12 inch king doll with royal garments and crown                       |
    13. | RYL02   | FNG01   | Queen doll          |       9.49 | 12 inch queen doll with royal garments and crown                      |
    15. 9 rows in set (0.00 sec)