Special characters, case sensitivity, and comments in ESQL

This topic describes the special characters used in ESQL, case sensitivity, and how comments are handled in the following sections:

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 wild card
% percent LIKE multiple wild card
\ 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 */.