MySQL 之 LOAD DATA INFILE 快速导入数据

Posted 2020-10-13 LEROI

 

SELECT INTO OUTFILE

> help select;
Name: ‘SELECT‘
Description:
Syntax:
SELECT
    [ALL | DISTINCT | DISTINCTROW ]
      [HIGH_PRIORITY]
      [MAX_STATEMENT_TIME = N]
      [STRAIGHT_JOIN]
      [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT]
      [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS]
    select_expr [, select_expr ...]
    [FROM table_references
      [PARTITION partition_list]
    [WHERE where_condition]
    [GROUP BY {col_name | expr | position}
      [ASC | DESC], ... [WITH ROLLUP]]
    [HAVING where_condition]
    [ORDER BY {col_name | expr | position}
      [ASC | DESC], ...]
    [LIMIT {[offset,] row_count | row_count OFFSET offset}]
    [PROCEDURE procedure_name(argument_list)]
    [INTO OUTFILE ‘file_name‘
        [CHARACTER SET charset_name]
        export_options
      | INTO DUMPFILE ‘file_name‘
      | INTO var_name [, var_name]]
    [FOR UPDATE | LOCK IN SHARE MODE]]

举例：

> select * from e;
+------+-------+-------+
| id   | fname | lname |
+------+-------+-------+
| 1669 | Jim   | Smith |
|  337 | Mary  | Jones |
| 2005 | Linda | Black |
+------+-------+-------+

> select * from e into outfile "/data/mysql/e.sql";
或
> select * into outfile "/data/mysql/e.sql" from e;
# cat e.sql     
1669    Jim     Smith
337     Mary    Jones
2005    Linda   Black

可以看到，select...into outfile 的结果只包含了表数据，默认以 Tab 分隔，也可指定分隔符：

> select * from e into outfile "/data/mysql/e.sql" fields terminated by ‘,‘;
# cat  e.sql    
1669,Jim,Smith
337,Mary,Jones
2005,Linda,Black

注意：outfile ‘/path/file‘，中的 path 需要有mysql的权限，否则会报错：

> select * from t into outfile "/root/backup/mysql/t.sql";
ERROR 1 (HY000): Can‘t create/write to file ‘/root/backup/mysql/t.sql‘ (Errcode: 13 - Permission denied)

 

LOAD DATA INFILE

LOAD DATA INFILE 语句以非常高的速度从文本文件中读取行到表中。

LOAD DATA [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE ‘file_name‘
[REPLACE | IGNORE]
INTO TABLE tbl_name
[PARTITION (partition_name,...)]
[CHARACTER SET charset_name]
[{FIELDS | COLUMNS}
[TERMINATED BY ‘string‘]
[[OPTIONALLY] ENCLOSED BY ‘char‘]
[ESCAPED BY ‘char‘]
]
[LINES
[STARTING BY ‘string‘]
[TERMINATED BY ‘string‘]
]
[IGNORE number {LINES | ROWS}]
[(col_name_or_user_var,...)]
[SET col_name = expr,...]

举例：

> delete from e;
> load data infile "/data/mysql/e.sql" into table e fields terminated by ‘,‘;
Query OK, 3 rows affected (0.01 sec)
Records: 3  Deleted: 0  Skipped: 0  Warnings: 0

> select * from e;
+------+-------+-------+
| id   | fname | lname |
+------+-------+-------+
| 1669 | Jim   | Smith |
|  337 | Mary  | Jones |
| 2005 | Linda | Black |
+------+-------+-------+

因为我们前面指定的分隔符是 ‘,‘，load data 时也要指定分隔符，否则也会报错：

> load data infile "/data/mysql/e.sql" into table e;
ERROR 1265 (01000): Data truncated for column ‘id‘ at row 1

 

如果数据被某种符号封闭着，需要指定 ‘ fields enclosed by ’ ：

# cat e.sql 
"1669"  "Jim"   "Smith"

　> load data infile "/data/mysql/e.sql" into table e;
　ERROR 1366 (HY000): Incorrect integer value: ‘"1669"‘ for column ‘id‘ at row 1

　> load data infile "/data/mysql/e.sql" into table e fields enclosed by ‘"‘;
　Query OK, 1 row affected (0.01 sec)
　Records: 1 Deleted: 0 Skipped: 0 Warnings: 0

如上所示，数据被双引号封闭着，如果直接执行，会报错。

另外还有一些格式上的限制，如 LINES TERMINATED BY ‘string‘ ，指定 file 的换行符，如 ‘\n’ 。