MySQL - Database Import - Recovery Methods


There are two simple ways in MySQL to load data into the MySQL database from a previously backed up file.

Importing Data with LOAD DATA

MySQL provides a LOAD DATA statement that acts as a bulk data loader. Here is an example statement that reads a file dump.txt from your current directory and loads it into the table mytbl in the current database.

mysql> LOAD DATA LOCAL INFILE 'dump.txt' INTO TABLE mytbl;
mysql> LOAD DATA LOCAL INFILE 'dump.txt' INTO TABLE mytbl
   -> FIELDS TERMINATED BY ':'
   -> LINES TERMINATED BY '\r\n';

You can load the file as shown in the following code block.

mysql> LOAD DATA LOCAL INFILE 'dump.txt' 
   -> INTO TABLE mytbl (b, c, a);

Importing Data with mysqlimport

MySQL also includes a utility program named mysqlimport that acts as a wrapper around LOAD DATA, so that you can load the input files directly from the command line.

To load data from the dump.txt into mytbl, use the following command at the UNIX prompt.

$ mysqlimport -u root -p --local database_name dump.txt
password *****

If you use mysqlimport, command-line options provide the format specifiers. The mysqlimport commands that correspond to the preceding two LOAD DATA statements looks as shown in the following code block.

$ mysqlimport -u root -p --local --fields-terminated-by = ":" \
   --lines-terminated-by = "\r\n"  database_name dump.txt
password *****

The order in which you specify the options doesn't matter for mysqlimport, except that they should all precede the database name.

The mysqlimport statement uses the --columns option to specify the column order −

$ mysqlimport -u root -p --local --columns=b,c,a \
   database_name dump.txt
password *****

Handling Quotes and Special Characters

The FIELDS clause can specify other format options besides TERMINATED BY. By default, LOAD DATA assumes that values are unquoted and interprets the backslash (\) as an escape character for the special characters. To indicate the value quoting character explicitly, use the ENCLOSED BY command. MySQL will strip that character from the ends of data values during input processing. To change the default escape character, use ESCAPED BY.

When you specify ENCLOSED BY to indicate that quote characters should be stripped from data values, it is possible to include the quote character literally within data values by doubling it or by preceding it with the escape character.

For example, if the quote and escape characters are " and \, the input value "a""b\"c" will be interpreted as a"b"c.

For mysqlimport, the corresponding command-line options for specifying quote and escape values are --fields-enclosed-by and --fields-escaped-by.