GoogleSQL for Spanner supports numbering functions. Numbering functions are a subset of window functions. To create a window function call and learn about the syntax for window functions, see Window function calls.
Numbering functions assign values to each row based on their position
within the specified window. The OVER
clause syntax varies across
numbering functions.
Function list
Name | Summary |
---|---|
IS_FIRST
|
Returns true if this row is in the first k rows (1-based) within the window.
|
IS_FIRST
IS_FIRST(k)
OVER over_clause
over_clause:
( [ window_specification ] )
window_specification:
[ PARTITION BY partition_expression [, ...] ]
[ ORDER BY expression [ { ASC | DESC } ] [, ...] ]
Description
Returns true
if the current row is in the first k
rows (1-based) in the
window; otherwise, returns false
. This function doesn't require the ORDER BY
clause.
Details
- The
k
value must be positive; otherwise, a runtime error is raised. - If any rows are tied or if
ORDER BY
is omitted, the result is non-deterministic. If theORDER BY
clause is unspecified or if all rows are tied, the result is equivalent toANY-k
.
To learn more about the OVER
clause and how to use it, see
Window function calls.
Return Type
BOOL