LOAD DATA INFILE - 拼命卡住

Question

希望我能解釋這不夠好......我有一個表叫artists基本上與2列，artist_pk（主鍵）和artist_name。我使用LOAD DATA INFILE將artist_name列的記錄通過CSV文件導入表artists，並讓MySQL提供artist_pk值。這一切都完成了。

現在我想爲我的表導入數據（通過相同的導入方法），名爲albums。這裏的三個相關列album_pk（主），album_name和artist_pk（從artists表的外鍵）。再次，我將讓mySQL分配album_pk值。

在我的CSV數據中有album_name和artist_name。我沒有artist_pk值。所以我的問題是：我可以導入artist_name CSV列作爲我的tables導入的一部分，但不是按原樣使用它，請指示mySQL使用artists表中的關聯artist_pk PRIMARY KEY值？

例如在artists表中的記錄：

artist_pk | artist_name | 
+-----------+--------------+ 
|  1 | Depeche Mode | 
+-----------+--------------+ 

現在從我的CSV文件（即我希望把我的albums表）的摘錄。

album_name artist_name 
Violator Depeche Mode 

'違規者'將填充albums.album_name。但爲了填充albums.artist_pk，我希望MySQL使用'Depeche Mode'（位於artists.artist_name）去獲得其相關值artist_pk（本例中爲1） - 這是表albums中的值。

在此先感謝！

Answer 1

假設artists表已經填充您可以利用會話變量和SET子句中LOAD DATA INFILE載入您的數據

做必要的查詢

LOAD DATA INFILE '/path/to/albums.txt' 
INTO TABLE albums 
FIELDS TERMINATED BY '\t' OPTIONALLY ENCLOSED BY '"' 
LINES TERMINATED BY '\n' 
IGNORE 1 LINES 
(album_name, @artist_name) -- use a session variable to store a value read from the file 
SET artist_pk = 
(
    SELECT artist_pk 
    FROM artists 
    WHERE artist_name = @artist_name -- use a session variable to get an artist_pk 
    LIMIT 1 -- this is to ensure that only one row will be returned 
) 

讓我們嘗試一下

 
mysql> CREATE TABLE artists (`artist_pk` int not null auto_increment primary key, `artist_name` varchar(12)); 
Query OK, 0 rows affected (0.07 sec) 

mysql> INSERT INTO artists (`artist_name`) VALUES ('Depeche Mode'); 
Query OK, 1 row affected (0.00 sec) 

mysql> CREATE TABLE albums (`album_pk` int not null auto_increment primary key, album_name varchar(255), artist_pk int, foreign key (artist_pk) references artists(artist_pk)); 
Query OK, 0 rows affected (0.03 sec) 

mysql> LOAD DATA INFILE '/tmp/albums.txt' 
    -> INTO TABLE albums 
    -> FIELDS TERMINATED BY '\t' OPTIONALLY ENCLOSED BY '"' 
    -> LINES TERMINATED BY '\n' 
    -> IGNORE 1 LINES 
    -> (album_name, @artist_name) 
    -> SET artist_pk = 
    -> (
    -> SELECT artist_pk 
    ->  FROM artists 
    -> WHERE artist_name = @artist_name 
    ->); 
Query OK, 1 row affected (0.01 sec) 
Records: 1 Deleted: 0 Skipped: 0 Warnings: 0 

mysql> select * from albums;                      
+----------+------------+-----------+ 
| album_pk | album_name | artist_pk | 
+----------+------------+-----------+ 
|  1 | Violator |   1 | 
+----------+------------+-----------+ 
1 row in set (0.00 sec)