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Literals. How do you write strings and numbers?

Strings

A string may have ' or " around it.

\ is a escape character. The following escape characters are recognised:

\0
An ascii 0 character.
\n
A newline character.
\t
A tab character.
\r
A return character.
\b
A backspace character.
\'
A ' character.
\"
A " character.
\\
A \ character.
\%
A % character. This is used in wildcard strings to search for %.
\_
A _ character. This is used in wildcard strings to search for _. 
A ' inside a string started with ' may be written as ".
A " inside a string started with " may be written as "".

Some example selects that shows how it works. 

MySQL> select 'hello', "'hello'", '""hello""', "'h"e"l"l"o"', "hel""lo";
1 rows in set (0.00 sec)

+-------+---------+-----------+-------------+--------+
| hello | 'hello' | ""hello"" | 'h'e'l'l'o' | hel"lo |
+-------+---------+-----------+-------------+--------+
| hello | 'hello' | ""hello"" | 'h'e'l'l'o' | hel"lo |
+-------+---------+-----------+-------------+--------+

mysql> select 'hello', "hello", '""hello""', "'ello", 'e"l"lo', '\'hello';
1 rows in set (0.00 sec)

+-------+-------+-----------+-------+--------+--------+
| hello | hello | ""hello"" | 'ello | e'l'lo | 'hello |
+-------+-------+-----------+-------+--------+--------+
| hello | hello | ""hello"" | 'ello | e'l'lo | 'hello |
+-------+-------+-----------+-------+--------+--------+

mysql> select "This\nIs\nFour\nlines";
1 rows in set (0.00 sec)

+--------------------+
| This
Is
Four
lines |
+--------------------+
| This
Is
Four
lines |
+--------------------+

If you want to insert binary data into a blob the following characters must be represented by escape sequences:

\0
Ascii 0. Should be replaced with "\0" (A backslash and a 0 digit).
\
Ascii 92, backslash
'
Ascii 39, Single quote
"
Ascii 33, Double quote

One doesn't have to escape " inside ' and " inside '.

If you write C code you can use the C API function mysql_escape_string(char *to,char *from,uint length) to escape characters for the INSERT clause. (Note that 'to' must be at least 2 times bigger than from). In perl you can use the quote function.

You should run the escape function on every possible string that may have a one of the above special characters!

Numbers

Integers are just a sequence of digits. Floats use . as a decimal separator.

Examples of valid numbers are: 1221, 294.42, -32032.6809e+10.

NULL

When using the text file export formats, NULL may be represented by \N. See section LOAD DATA INFILE syntax

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