Literals
- Technische Redaktion
A literal represents a constant value of a particular type. eSQL provides a literal syntax for most simple types. Literals are mostly used in the WHERE clause in order to form conditions. They can also be used in the SELECT clause.
String
A string is a sequence of characters enclosed in single inverted commas.
'sample text'
Use two single inverted commas when you want to embed an inverted comma into a string:
'What''s going on?'
LongString
A LongString is a sequence of characters enclosed in single inverted commas, followed by the letter 'L.'
'sample text'L
Boolean
With Boolean literals, statements are made using logical values.
true
false
DateTime
The DateTime literal is comprised of date and time information that are independent of the locale, and is enclosed in single inverted commas. It follows the syntax yyyy-mm-dd hh:mm:ss. All data are optional, hence the times starting with the smallest time unit can be omitted.
datetime'2010-06-30 16:30'
datetime'2012-06-30 16:30'
datetime'2012'
For omitted data, the smallest possible value is used.
datetime'2012-06-30 16:30'
and
datetime'2012-06-30 16:30:00'
are synonymous.
datetime'2012'
and
datetime'2012-01-01 00:00:00'
are also synonymous.
LongDateTime
The LongDateTime literal only differs from the DateTime literal in that it follows the more precise syntax yyyy-mm-dd hh:mm:ss.sss and ends with the letter 'L.'
datetime'2012-06-30 16:30:15.111'L
ID Literal
An ID literal consists of the keyword 'id' followed by a 32-character string.
id'ABCDEF12345678901234567890123456'
Integer
An integer literal is one or several consecutive digits that are not enclosed by inverted commas and are not part of a decimal literal.
42
Long
A long literal is an integer literal followed by the letter 'L.'
42L
Decimal
A decimal literal is a fixed-point number that follows the syntax 'number.number E+-number'. The individual components of the syntax are optional.
3.14
.5
7 e14
5.5 e-42
Integer, long, and decimal literals can have a prefixed sign (+ or -).