Special characters, case sensitivity, and comments in ESQL
When you work with ESQL, it is useful to know about the special characters that are available, whether ESQL syntax is case sensitive, and how to handle comments.
Special characters
Symbol | Name | Usage |
---|---|---|
; | semicolon | End of ESQL statement |
. | period | Field reference separator or decimal point |
= | equals | Comparison or assignment |
> | greater than | Comparison |
< | less than | Comparison |
[] | square brackets | Array subscript |
' | single quotation mark | Delimit string, date-time, and decimal literals Note, that to escape a single quotation mark inside a string literal, you must use two single quotation marks. |
|| | double vertical bar | Concatenation |
() | parentheses | Expression delimiter |
" | quotation mark | Identifier delimiter |
* | asterisk | Any name or multiply |
+ | plus | Arithmetic add |
- | minus | Arithmetic subtract, date separator, or negation |
/ | forward slash | Arithmetic divide |
_ | underscore | LIKE single wildcard |
% | percent | LIKE multiple wildcard |
\ | backslash | LIKE escape character |
: | colon | Name space and Time literal separator |
, | comma | List separator |
<> | less than greater than | Not equals |
-- | double minus | ESQL single line comment |
/* */ | slash asterisk asterisk slash | ESQL multiline comment |
? | question mark | Substitution variable in PASSTHRU |
<= | less than or equal | Comparison |
>= | greater than or equal | Comparison |
/*!{ }!*/ | executable comment | Bypass tools check |
Case sensitivity of ESQL syntax
The
case of ESQL statements is:
- Case sensitive in field reference literals
- Not case sensitive in ESQL language words
Comments
ESQL has two types
of comment: single line and multiple line. A single line comment starts
with the characters --
and ends at the end of the
line.
In arithmetic expressions you must take care not to initiate
a line comment accidentally. For example, consider the expression:
1 - -2
Removing all white space from
the expression results in:
1--2
which is interpreted as the number 1, followed by a line comment.
A
multiple line comment starts with /*
anywhere in
ESQL and ends with */
.