Expressions

One of the major difference from tradtional SQL is that wvlet uses single or double quoted strings for representing string values, and back-quoted strings for referencing column or table names, which might contain space or special characters.

Operator	Description
'(single quote)'	String literal for representing string values, file names, etc.
"(double quote)"	Same as single quote strings
"""(triple quote string)"""	Multi-line strings
`(back quote)`	Column or table name, which requires quotations
sql"sql expr"	SQL expression used for inline expansion
sql" ... ${expr} ..."	Interpolated SQL expression with embedded expressions
s"... ${expr} ..."	Interpolated strings with expressions
s`... ${expr} ...`	Interpolated backquote strings with expressions
[expr, ...]	Array value
[[expr, ...], ...]	Array of arrays for representing table records
_	underscore refers to the previous input
agg_func(expr) over (partition by ... order by ...)	Window functions for computing aggregate values computed from the entire query result. This follows the same window function syntax with SQL
_1, _2, ...	Refers to 1-origin grouping keys in the preceding group by clause
1, 2, ...	Refers to 1-origin column index for order by clause

Variable Definition

You can define a variable using val keyword:

-- Define a new variable
val name = 'wvlet'

-- Variable is evaluated once before running the query
select s"Hello ${x}!" as msg
-- Returns [['Hello wvlet!']]

Conditional Expressions

Operator	Description
expr and expr	Logical AND
expr or expr	Logical OR
not expr	Logical NOT
!expr	Logical NOT
expr is expr	equality check
expr = expr	equality check
expr is not expr	inequality check
expr != expr	inequality check
expr is null	True if the expression is null
expr = null	True if the expression is null
expr is not null	True if the expression is not null
expr != null	True if the expression is not null.
expr in (v1, v2, ...)	True if the expression value is in the given list
expr in (from ...)	True if the expression value is in the given list provided by a sub query
expr not in (v1, v2, ...)	True if the expression is not in the given list
expr between v1 and v2	True if the expression value is between v1 and v2, i.e., v1 ≤ (value) ≤ v2
expr like pattern	True if the expression matches the given pattern, e.g., , 'abc%'

String Expressions

Operator	Description
expr + expr	Concatenate two strings