读书笔记--SQL必知必会15--插入数据

15.1 数据插入

使用INSERT语句将行插入（或添加）到数据库表。可能需要特定的安全权限。

• 插入完整的行
• 插入行的一部分
• 插入某些查询的结果

15.1.1 插入完整的行

要求指定表名和插入到新行中的值。

存储到表中每一列的数据在VALUES子句中给出，必须给每一列提供一个值。如果某列没有值，则应该使用NULL值（假定表允许对该列指定空值）。

各列必须以它们在表定义中的次序填充。

在某些SQL实现中，跟在INSERT之后的INTO关键字是可选的，但建议提供这个关键字，保证移植性。

MariaDB [sqlbzbh]> SELECT * FROM Customers;
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| cust_id    | cust_name     | cust_address         | cust_city | cust_state | cust_zip | cust_country | cust_contact       | cust_email            |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| 1000000001 | Village Toys  | 200 Maple Lane       | Detroit   | MI         | 44444    | USA          | John Smith         | sales@villagetoys.com |
| 1000000002 | Kids Place    | 333 South Lake Drive | Columbus  | OH         | 43333    | USA          | Michelle Green     | NULL                  |
| 1000000003 | Fun4All       | 1 Sunny Place        | Muncie    | IN         | 42222    | USA          | Jim Jones          | jjones@fun4all.com    |
| 1000000004 | Fun4All       | 829 Riverside Drive  | Phoenix   | AZ         | 88888    | USA          | Denise L. Stephens | dstephens@fun4all.com |
| 1000000005 | The Toy Store | 4545 53rd Street     | Chicago   | IL         | 54545    | USA          | Kim Howard         | NULL                  |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
5 rows in set (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> INSERT INTO Customers VALUES('1000000006','Toy Land','123 Any Street','New York','NY','11111','USA',NULL,NULL);
Query OK, 1 row affected (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> SELECT * FROM Customers;
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| cust_id    | cust_name     | cust_address         | cust_city | cust_state | cust_zip | cust_country | cust_contact       | cust_email            |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| 1000000001 | Village Toys  | 200 Maple Lane       | Detroit   | MI         | 44444    | USA          | John Smith         | sales@villagetoys.com |
| 1000000002 | Kids Place    | 333 South Lake Drive | Columbus  | OH         | 43333    | USA          | Michelle Green     | NULL                  |
| 1000000003 | Fun4All       | 1 Sunny Place        | Muncie    | IN         | 42222    | USA          | Jim Jones          | jjones@fun4all.com    |
| 1000000004 | Fun4All       | 829 Riverside Drive  | Phoenix   | AZ         | 88888    | USA          | Denise L. Stephens | dstephens@fun4all.com |
| 1000000005 | The Toy Store | 4545 53rd Street     | Chicago   | IL         | 54545    | USA          | Kim Howard         | NULL                  |
| 1000000006 | Toy Land      | 123 Any Street       | New York  | NY         | 11111    | USA          | NULL               | NULL                  |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
6 rows in set (0.00 sec)

MariaDB [sqlbzbh]>

表的结构有可能变动，因此编写特定次序的SQL语句，后期可能无法使用。

可以在表名后的括号里明确相应的列名，这样相应的值就会填入列表中的对应项，即使表的结构改变，INSERT语句仍然能够正确工作。

推荐明确给出表的列名，不要使用没有明确给出列的INSERT语句。

MariaDB [sqlbzbh]> INSERT INTO Customers(cust_id,cust_name,cust_address,cust_city,cust_state,cust_zip,cust_country,cust_contact,cust_email)
    -> VALUES('1000000006','Toy Land','123 Any Street','New York','NY','11111','USA',NULL,NULL);
Query OK, 1 row affected (0.00 sec)

MariaDB [sqlbzbh]>

因为给出了列名，并且和相应值对应，插入数据就可以不按各列出现在表中的实际次序。

MariaDB [sqlbzbh]> INSERT INTO Customers(cust_id,cust_contact,cust_email,cust_name,cust_address,cust_city,cust_state,cust_zip)
    -> VALUES('1000000006',NULL,NULL,'Toy Land','123 Any Street','New York','NY','11111');
Query OK, 1 row affected (0.01 sec)

MariaDB [sqlbzbh]>

15.1.2 插入部分行

如果表的定义允许有NULL值或者默认值，可以只明确给出表的某些列名，并只给这些列提供值，其他列不提供，也就是省略了某些列。

省略的列必须满足以下某个条件：

• 该列定义为允许NULL值。
• 在表定义中给出默认值（如果不给出值，将使用默认值）。

15.1.3 插入检索出的数据

可以利用INSERT语句将SELECT语句的结果插入表中。

所谓的INSERT SELECT，顾名思义，就是由一条INSERT语句和一条SELECT语句组成的。

INSERT和SELECT语句是使用列的位置，因此列名不一定匹配。

INSERT SELECT中的SELECT语句可以包含WHERE子句。

INSERT通常只插入一行，而INSERT SELECT插入的行数取决于SELECT语句返回多少行。

MariaDB [sqlbzbh]> SELECT * FROM Customers;
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| cust_id    | cust_name     | cust_address         | cust_city | cust_state | cust_zip | cust_country | cust_contact       | cust_email            |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| 1000000001 | Village Toys  | 200 Maple Lane       | Detroit   | MI         | 44444    | USA          | John Smith         | sales@villagetoys.com |
| 1000000002 | Kids Place    | 333 South Lake Drive | Columbus  | OH         | 43333    | USA          | Michelle Green     | NULL                  |
| 1000000003 | Fun4All       | 1 Sunny Place        | Muncie    | IN         | 42222    | USA          | Jim Jones          | jjones@fun4all.com    |
| 1000000004 | Fun4All       | 829 Riverside Drive  | Phoenix   | AZ         | 88888    | USA          | Denise L. Stephens | dstephens@fun4all.com |
| 1000000005 | The Toy Store | 4545 53rd Street     | Chicago   | IL         | 54545    | USA          | Kim Howard         | NULL                  |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
5 rows in set (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> SELECT * FROM CustNew;
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
| cust_id    | cust_name | cust_address   | cust_city | cust_state | cust_zip | cust_country | cust_contact | cust_email |
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
| 1000000006 | Toy Land  | 123 Any Street | New York  | NY         | 11111    | USA          | NULL         | NULL       |
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
1 row in set (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> INSERT INTO Customers(cust_id,cust_name,cust_address,cust_city,cust_state,cust_zip,cust_country,cust_contact,cust_email)
    -> SELECT cust_id,cust_name,cust_address,cust_city,cust_state,cust_zip,cust_country,cust_contact,cust_email
    -> FROM CustNew;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> SELECT * FROM Customers;
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| cust_id    | cust_name     | cust_address         | cust_city | cust_state | cust_zip | cust_country | cust_contact       | cust_email            |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
| 1000000001 | Village Toys  | 200 Maple Lane       | Detroit   | MI         | 44444    | USA          | John Smith         | sales@villagetoys.com |
| 1000000002 | Kids Place    | 333 South Lake Drive | Columbus  | OH         | 43333    | USA          | Michelle Green     | NULL                  |
| 1000000003 | Fun4All       | 1 Sunny Place        | Muncie    | IN         | 42222    | USA          | Jim Jones          | jjones@fun4all.com    |
| 1000000004 | Fun4All       | 829 Riverside Drive  | Phoenix   | AZ         | 88888    | USA          | Denise L. Stephens | dstephens@fun4all.com |
| 1000000005 | The Toy Store | 4545 53rd Street     | Chicago   | IL         | 54545    | USA          | Kim Howard         | NULL                  |
| 1000000006 | Toy Land      | 123 Any Street       | New York  | NY         | 11111    | USA          | NULL               | NULL                  |
+------------+---------------+----------------------+-----------+------------+----------+--------------+--------------------+-----------------------+
6 rows in set (0.00 sec)

MariaDB [sqlbzbh]>

15.2 从一个表复制到另一个表

SELECT INTO语句可以将一个表的内容复制到一个全新的表（运行中创建的表）。

• 任何SELECT选项和子句都可以使用
• 可利用联结从多个表插入数据
• 数据都只能一次插入到一个表中

在MySQL和MariaDB中使用的语法不同于SELECT INTO语句。

MariaDB [sqlbzbh]> SHOW TABLES;
+-------------------+
| Tables_in_sqlbzbh |
+-------------------+
| CustNew           |
| Customers         |
| OrderItems        |
| Orders            |
| Products          |
| Vendors           |
+-------------------+
6 rows in set (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> CREATE TABLE CustCopy AS SELECT * FROM CustNew;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> SHOW TABLES;
+-------------------+
| Tables_in_sqlbzbh |
+-------------------+
| CustCopy          |
| CustNew           |
| Customers         |
| OrderItems        |
| Orders            |
| Products          |
| Vendors           |
+-------------------+
7 rows in set (0.00 sec)

MariaDB [sqlbzbh]>
MariaDB [sqlbzbh]> SELECT * FROM CustCopy
    -> ;
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
| cust_id    | cust_name | cust_address   | cust_city | cust_state | cust_zip | cust_country | cust_contact | cust_email |
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
| 1000000006 | Toy Land  | 123 Any Street | New York  | NY         | 11111    | USA          | NULL         | NULL       |
+------------+-----------+----------------+-----------+------------+----------+--------------+--------------+------------+
1 row in set (0.00 sec)

MariaDB [sqlbzbh]>