4.2.1 Problem
You want to write a quoted string, but it contains quote characters or other special characters, and MySQL rejects it.
4.2.2 Solution
Learn the syntax rules that govern the interpretation of strings in queries.
4.2.3 Discussion
To write a string in a SQL statement, surround it with quote characters:
mysql> SELECT 'hello, world'; +--------------+ | hello, world | +--------------+ | hello, world | +--------------+
But sometimes you need to write a string that includes a quote character, and if you just put the quote into the string as is, a syntax error results:
mysql> SELECT 'I'm asleep'; ERROR 1064 at line 1: You have an error in your SQL syntax near 'asleep'' at line 1
You can deal with this several ways:
mysql> SELECT "I'm asleep"; +------------+ | I'm asleep | +------------+ | I'm asleep | +------------+
This works in reverse, too; a string containing double quotes can be enclosed within single quotes:
mysql> SELECT 'He said, "Boo!"'; +-----------------+ | He said, "Boo!" | +-----------------+ | He said, "Boo!" | +-----------------+
mysql> SELECT 'I''m asleep', 'I'm wide awake'; +------------+----------------+ | I'm asleep | I'm wide awake | +------------+----------------+ | I'm asleep | I'm wide awake | +------------+----------------+ 1 row in set (0.00 sec) mysql> SELECT "He said, ""Boo!""", "And I said, "Yikes!""; +-----------------+----------------------+ | He said, "Boo!" | And I said, "Yikes!" | +-----------------+----------------------+ | He said, "Boo!" | And I said, "Yikes!" | +-----------------+----------------------+
A backslash turns off the special meaning of the following character. (It causes a temporary escape from normal string processing rules, so sequences such as ' and " are called escape sequences.) This means that backslash itself is special, so to write a literal backslash within a string, you must double it:
mysql> SELECT 'Install MySQL in C:\mysql on Windows'; +--------------------------------------+ | Install MySQL in C:mysql on Windows | +--------------------------------------+ | Install MySQL in C:mysql on Windows | +--------------------------------------+
Other escape sequences recognized by MySQL are (backspace), (newline, also called linefeed), (carriage return), (tab), and