String literals are specified by one or more characters enclosed in single quotes. The default data type for string literals is varchar, but a string literal can be assigned to any character data type or to money or date data type without using a data type conversion function.

SQL will attempt to implicitly cast a string literal to a non-string type such as integer, if required. To avoid unexpected results, however, it is better to use the appropriate non-string literal, or explicitly cast the string literal to the desired type.

For example, given a cust table with a cust_no integer column:

will work but requires SQL to guess at the proper coercion. Preferred syntax is:

or simply

Strings can contain embedded non-printing characters. To write a string literal that matches such values, you can use literals or concatenations of regular quoted string literals, hexadecimal literals, or Unicode literals.

To specify a non-printing character in terminal monitor, use a hex (hexadecimal) constant.

Hex constants are specified by an X followed by a single-quoted string composed of (an even number of) alphanumeric characters. For example, the following represents the ASCII string ABC<carriage return>:

An alternative is to use a prefix of 0x. That is, 0xstring composed of (an even number of) alphanumeric characters:

To include a single quote inside a string literal, it must be doubled. For example:

which is evaluated as:

To specify a Unicode literal value within a non-Unicode command string (for example, in a query entered into the terminal monitor), the Unicode literal notation can be used. A Unicode literal is a sequence of ASCII characters intermixed with escaped sequence of hex digits, all enclosed in quotes and preceded by U&. The escape character \ precedes sets of 4 hex digits that are treated as Unicode codepoints from Plane 0 (the Basic Multilingual Plane) and the escape sequence \+ precedes sequences of 6 hex digits that are treated as codepoints from the Supplementary Plane. Note that this may require a leading 0. For example:

In this string, Hello is converted to the equivalent Unicode codepoints, the hex digits 202F represent codepoint U+202F (the narrow non-breaking space), world is converted to the equivalent Unicode codepoints, and the hex digits 029E71 represent codepoint U+29E71 (the Chinese ideograph chù from Plane 2). The resulting literal is the concatenation of the converted Unicode components.

The notation N'x' can be used as an alternative to the U&'x' notation.