使用 mysql 的 load infile 仅填充某些列

Question

我有一个包含大量数据的 csv 文件，我想将其上传到 mysql 表中。但是，我想保留一列（主 ID）为空，以便我可以自己编辑它。在 mysql 的文档中，它说您可以指定列，但从我的研究来看，您似乎只能指定 csv 文件的列。

那么是否可以指定表的列

Answer 1

检查这个例子：

# cat /tmp/db.txt
id,col1,col2
1,23,"dsafsdf"
2,-1,"ghfdhg"
7,9,"strsdrt"

# mysql test
mysql> CREATE TABLE `test` (
       `id` int(11) NOT NULL,
       `mycol1` int(11) DEFAULT NULL,
       `mycol2` varchar(20) DEFAULT NULL,
       PRIMARY KEY (`id`);

mysql> LOAD DATA INFILE '/tmp/db.txt'
       INTO TABLE test FIELDS TERMINATED BY ','
       OPTIONALLY ENCLOSED BY '"'
       IGNORE 1 LINES (id, mycol1, mycol2);

Query OK, 3 rows affected (0.00 sec)
Records: 3  Deleted: 0  Skipped: 0  Warnings: 0

mysql> SELECT * FROM test;
+----+--------+---------+
| id | mycol1 | mycol2  |
+----+--------+---------+
|  1 |     23 | dsafsdf |
|  2 |     -1 | ghfdhg  |
|  7 |      9 | strsdrt |
+----+--------+---------+
3 rows in set (0.00 sec)

如果要指定某些列：

mysql> TRUNCATE test;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM test;
Empty set (0.00 sec)

mysql> LOAD DATA INFILE '/tmp/db.txt'
       INTO TABLE test FIELDS TERMINATED BY ','
       OPTIONALLY ENCLOSED BY '"'
       IGNORE 1 LINES (id, @ignore, mycol2);

Query OK, 3 rows affected (0.00 sec)
Records: 3  Deleted: 0  Skipped: 0  Warnings: 0

mysql> SELECT * FROM test;
+----+--------+---------+
| id | mycol1 | mycol2  |
+----+--------+---------+
|  1 |   NULL | dsafsdf |
|  2 |   NULL | ghfdhg  |
|  7 |   NULL | strsdrt |
+----+--------+---------+
3 rows in set (0.00 sec)

你甚至可以用你自己的表达式设置它们：

mysql> TRUNCATE test;
Query OK, 0 rows affected (0.00 sec)

mysql> LOAD DATA INFILE '/tmp/db.txt'
       INTO TABLE test FIELDS TERMINATED BY00 ','
       OPTIONALLY ENCLOSED by '"' IGNORE 1 LINES (id, @var1, mycol2)
       SET mycol1 = @var1 + 1;

Query OK, 3 rows affected (0.00 sec)
Records: 3  Deleted: 0  Skipped: 0  Warnings: 0

mysql> SELECT * FROM test;
+----+--------+---------+
| id | mycol1 | mycol2  |
+----+--------+---------+
|  1 |     24 | dsafsdf |
|  2 |      0 | ghfdhg  |
|  7 |     10 | strsdrt |
+----+--------+---------+
3 rows in set (0.00 sec)

但是，请理解主键不能为空也不能重复，因此您不能将其设置为 NULL，除非它获得默认值，例如，因为它是一个 auto_increment 列。