mysql - 从使用双引号作为转义字符的 CSV 文件加载数据

Question

我有一堆 CSV 数据需要加载到 MySQL 数据库中。好吧，也许是 CSV-ish。 (编辑:actually, it looks like the stuff described in RFC 4180)

每一行都是逗号分隔的双引号字符串列表。要转义列值中出现的任何双引号，请使用双引号。允许反斜杠代表自己。

例如，行:

"", "\wave\", ""hello,"" said the vicar", "what are ""scare-quotes"" good for?", "I'm reading ""Bossypants"""

如果解析成JSON应该是:

[ "", "\\wave\\", "\"hello,\" said the vicar", "what are \"scare-quotes\" good for?", "I'm reading \"Bossypants\"" ]

我正在尝试使用 LOAD DATA 读取 CSV，但我遇到了一些奇怪的行为。

---

举个例子，假设我有一个简单的两列表

shell% mysql exampledb -e "describe person"
+-------+-----------+------+-----+---------+-------+
| Field | Type      | Null | Key | Default | Extra |
+-------+-----------+------+-----+---------+-------+
| ID    | int(11)   | YES  |     | NULL    |       |
| UID   | char(255) | YES  |     | NULL    |       |
+-------+-----------+------+-----+---------+-------+
shell%

如果我的输入文件的第一个非标题行以 "" 结尾:

shell% cat temp-1.csv
"ID","UID"
"9",""
"0","Steve the Pirate"
"1","\Alpha"
"2","Hoban ""Wash"" Washburne"
"3","Pastor Veal"
"4","Tucker"
"10",""
"5","Simon"
"6","Sonny"
"7","Wat\"

我可以加载除第一行以外的所有非标题行:

mysql> DELETE FROM person;
Query OK, 0 rows affected (0.00 sec)

mysql> LOAD DATA
          LOCAL INFILE 'temp-1.csv'
          INTO TABLE person
          FIELDS
            TERMINATED BY ','
            ENCLOSED BY '"'
            ESCAPED BY '"'
          LINES
            TERMINATED BY '\n'
          IGNORE 1 LINES
       ;
Query OK, 9 rows affected (0.00 sec)
Records: 9  Deleted: 0  Skipped: 0  Warnings: 0

mysql> SELECT * FROM person;
+------+------------------------+
| ID   | UID                    |
+------+------------------------+
|    0 | Steve the Pirate       |
|   10 |                        |
|    1 | \Alpha                 |
|    2 | Hoban "Wash" Washburne |
|    3 | Pastor Veal            |
|    4 | Tucker                 |
|    5 | Simon                  |
|    6 | Sonny                  |
|    7 | Wat\                   |
+------+------------------------+
9 rows in set (0.00 sec)

或者我可以加载所有行，包括标题:

mysql> DELETE FROM person;
Query OK, 9 rows affected (0.00 sec)

mysql> LOAD DATA
          LOCAL INFILE 'temp-1.csv'
          INTO TABLE person
          FIELDS
            TERMINATED BY ','
            ENCLOSED BY '"'
            ESCAPED BY '"'
          LINES
            TERMINATED BY '\n'
          IGNORE 0 LINES
       ;
Query OK, 11 rows affected, 1 warning (0.01 sec)
Records: 11  Deleted: 0  Skipped: 0  Warnings: 1

mysql> show warnings;
+---------+------+--------------------------------------------------------+
| Level   | Code | Message                                                |
+---------+------+--------------------------------------------------------+
| Warning | 1366 | Incorrect integer value: 'ID' for column 'ID' at row 1 |
+---------+------+--------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT * FROM person;
+------+------------------------+
| ID   | UID                    |
+------+------------------------+
|    0 | UID                    |
|    9 |                        |
|    0 | Steve the Pirate       |
|   10 |                        |
|    1 | \Alpha                 |
|    2 | Hoban "Wash" Washburne |
|    3 | Pastor Veal            |
|    4 | Tucker                 |
|    5 | Simon                  |
|    6 | Sonny                  |
|    7 | Wat\                   |
+------+------------------------+
11 rows in set (0.00 sec)

如果我的输入文件中没有任何行以 "" 结尾:

shell% cat temp-2.csv
"ID","UID"
"0","Steve the Pirate"
"1","\Alpha"
"2","Hoban ""Wash"" Washburne"
"3","Pastor Veal"
"4","Tucker"
"5","Simon"
"6","Sonny"
"7","Wat\"

然后我可以不加载任何行:

mysql> DELETE FROM person;
Query OK, 11 rows affected (0.00 sec)

mysql> LOAD DATA
          LOCAL INFILE 'temp-2.csv'
          INTO TABLE person
          FIELDS
            TERMINATED BY ','
            ENCLOSED BY '"'
            ESCAPED BY '"'
          LINES
            TERMINATED BY '\n'
          IGNORE 1 LINES
       ;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Deleted: 0  Skipped: 0  Warnings: 0

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

或者我可以加载所有行，包括标题:

mysql> DELETE FROM person;
Query OK, 0 rows affected (0.00 sec)

mysql> LOAD DATA
          LOCAL INFILE 'temp-2.csv'
          INTO TABLE person
          FIELDS
            TERMINATED BY ','
            ENCLOSED BY '"'
            ESCAPED BY '"'
          LINES
            TERMINATED BY '\n'
          IGNORE 0 LINES
       ;
Query OK, 9 rows affected, 1 warning (0.03 sec)
Records: 9  Deleted: 0  Skipped: 0  Warnings: 1

mysql> show warnings;
+---------+------+--------------------------------------------------------+
| Level   | Code | Message                                                |
+---------+------+--------------------------------------------------------+
| Warning | 1366 | Incorrect integer value: 'ID' for column 'ID' at row 1 |
+---------+------+--------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT * FROM person;
+------+------------------------+
| ID   | UID                    |
+------+------------------------+
|    0 | UID                    |
|    0 | Steve the Pirate       |
|    1 | \Alpha                 |
|    2 | Hoban "Wash" Washburne |
|    3 | Pastor Veal            |
|    4 | Tucker                 |
|    5 | Simon                  |
|    6 | Sonny                  |
|    7 | Wat\                   |
+------+------------------------+
9 rows in set (0.00 sec)

现在我发现了很多错误的方法，我如何使用 LOAD DATA 将这些文件中的数据导入我的数据库？

Answer 1

根据the documentation for LOAD DATA, treating doubled double quotes as a double quote is the default :

If the field begins with the ENCLOSED BY character, instances of that character are recognized as terminating a field value only if followed by the field or line TERMINATED BY sequence. To avoid ambiguity, occurrences of the ENCLOSED BY character within a field value can be doubled and are interpreted as a single instance of the character. For example, if ENCLOSED BY '"' is specified, quotation marks are handled as shown here:

"The ""BIG"" boss"  -> The "BIG" boss
The "BIG" boss      -> The "BIG" boss
The ""BIG"" boss    -> The ""BIG"" boss

所以我需要做的就是禁用将 \ 解释为转义字符，方法是使用 ESCAPED BY ''。

LOAD DATA
  LOCAL INFILE 'temp-1.csv'
  INTO TABLE person
  FIELDS
    TERMINATED BY ','
    ENCLOSED BY '"'
    ESCAPED BY ''
  LINES
    TERMINATED BY '\n'
  IGNORE 1 LINES
;