Operators in Dataflow SQL

Operators are represented by special characters or keywords; they do not use function call syntax. An operator manipulates any number of data inputs, also called operands, and returns a result.

Common conventions:

• Unless otherwise specified, all operators return NULL when one of the operands is NULL.

The following table lists all Cloud Dataflow SQL operators from highest to lowest precedence, i.e. the order in which they will be evaluated within a statement.

Order of Precedence	Operator	Input Data Types	Name	Operator Arity
1	.	STRUCT	Member field access operator	Binary
	[ ]	ARRAY	Not supported. To access elements in an ARRAY, use the UNNEST function ( see unnest ARRAY ).	Binary
2	-	All numeric types	Unary minus	Unary
3	*	All numeric types	Multiplication	Binary
	/	All numeric types	Division	Binary
4	+	All numeric types	Addition	Binary
	-	All numeric types	Subtraction	Binary
5 (Comparison Operators)	=	Any comparable type. See Data Types for a complete list.	Equal	Binary
	<	Any comparable type. See Data Types for a complete list.	Less than	Binary
	>	Any comparable type. See Data Types for a complete list.	Greater than	Binary
	<=	Any comparable type. See Data Types for a complete list.	Less than or equal to	Binary
	>=	Any comparable type. See Data Types for a complete list.	Greater than or equal to	Binary
	!=, <>	Any comparable type. See Data Types for a complete list.	Not equal	Binary
	[NOT] LIKE	STRING and byte	Value does [not] match the pattern specified	Binary
	[NOT] BETWEEN	Any comparable types. See Data Types for list.	Value is [not] within the range specified	Binary
	[NOT] IN	Any comparable types. See Data Types for list.	Value is [not] in the set of values specified	Binary
	IS [NOT] NULL	All	Value is [not] NULL	Unary
	IS [NOT] TRUE	BOOL	Value is [not] TRUE.	Unary
	IS [NOT] FALSE	BOOL	Value is [not] FALSE.	Unary
6	NOT	BOOL	Logical NOT	Unary
7	AND	BOOL	Logical AND	Binary
8	OR	BOOL	Logical OR	Binary

Operators with the same precedence are left associative. This means that those operators are grouped together starting from the left and moving right. For example, the expression:

x AND y AND z

is interpreted as

( ( x AND y ) AND z )

The expression:

x * y / z

is interpreted as:

( ( x * y ) / z )

All comparison operators have the same priority and are grouped using left associativity. However, comparison operators are not associative. As a result, it is recommended that you use parentheses to improve readability and ensure expressions are resolved as desired. For example:

(x < y) IS FALSE

is recommended over:

x < y IS FALSE

Element access operators

Operator	Syntax	Input Data Types	Result Data Type	Description
.	expression.fieldname1...	STRUCT	Type T stored in fieldname1	Dot operator. Can be used to access nested fields, e.g.expression.fieldname1.fieldname2...
[ ]	array_expression [position_keyword (int_expression ) ]	ARRAY	Type T stored in ARRAY	Not supported. To access elements in an ARRAY, use the UNNEST function ( see unnest ARRAY ).

Arithmetic operators

All arithmetic operators accept input of numeric type T, and the result type has type T unless otherwise indicated in the description below:

Name	Syntax
Addition	X + Y
Subtraction	X - Y
Multiplication	X * Y
Division	X / Y
Unary Minus	- X

Result types for Addition and Multiplication:

	INT64	FLOAT64
INT64	INT64	FLOAT64
FLOAT64	FLOAT64	FLOAT64

Result types for Subtraction:

	INT64	FLOAT64
INT64	INT64	FLOAT64
FLOAT64	FLOAT64	FLOAT64

Result types for Division:

	INT64	FLOAT64
INT64	FLOAT64	FLOAT64
FLOAT64	FLOAT64	FLOAT64

Result types for Unary Minus:

Input Data Type	Result Data Type
INT64	INT64
FLOAT64	FLOAT64

Logical operators

All logical operators allow only BOOL input.

Name	Syntax	Description
Logical NOT	NOT X	Returns FALSE if input is TRUE. Returns TRUE if input is FALSE. Returns NULL otherwise.
Logical AND	X AND Y	Returns FALSE if at least one input is FALSE. Returns TRUE if both X and Y are TRUE. Returns NULL otherwise.
Logical OR	X OR Y	Returns FALSE if both X and Y are FALSE. Returns TRUE if at least one input is TRUE. Returns NULL otherwise.

Comparison operators

Comparisons always return BOOL. Comparisons generally require both operands to be of the same type. If operands are of different types, and if Cloud Dataflow SQL can convert the values of those types to a common type without loss of precision, Cloud Dataflow SQL will generally coerce them to that common type for the comparison; Cloud Dataflow SQL will generally coerce literals to the type of non-literals, where present. Comparable data types are defined in Data Types.

STRUCTs support only 4 comparison operators: equal (=), not equal (!= and <>), and IN.

The following rules apply when comparing these data types:

• FLOAT64 : All comparisons with NaN return FALSE, except for != and <>, which return TRUE.
• BOOL: FALSE is less than TRUE.
• STRING: Strings are compared codepoint-by-codepoint, which means that canonically equivalent strings are only guaranteed to compare as equal if they have been normalized first.
• NULL: The convention holds here: any operation with a NULL input returns NULL.

Name	Syntax	Description
Less Than	X < Y	Returns TRUE if X is less than Y.
Less Than or Equal To	X <= Y	Returns TRUE if X is less than or equal to Y.
Greater Than	X > Y	Returns TRUE if X is greater than Y.
Greater Than or Equal To	X >= Y	Returns TRUE if X is greater than or equal to Y.
Equal	X = Y	Returns TRUE if X is equal to Y.
Not Equal	X != Y X <> Y	Returns TRUE if X is not equal to Y.
BETWEEN	X [NOT] BETWEEN Y AND Z	Returns TRUE if X is [not] within the range specified. The result of "X BETWEEN Y AND Z" is equivalent to "Y <= X AND X <= Z" but X is evaluated only once in the former.
LIKE	X [NOT] LIKE Y	Checks if the STRING in the first operand X matches a pattern specified by the second operand Y. Expressions can contain these characters: A percent sign "%" matches any number of characters or bytes An underscore "_" matches a single character or byte You can escape "\", "_", or "%" using two backslashes. For example, "\\%". If you are using raw strings, only a single backslash is required. For example, r"\%".
IN	Multiple - see below	Returns FALSE if the right operand is empty. Returns NULL if the left operand is NULL. Returns TRUE or NULL, never FALSE, if the right operand contains NULL. Arguments on either side of IN are general expressions. Neither operand is required to be a literal, although using a literal on the right is most common. X is evaluated only once.

When testing values that have a STRUCT data type for equality, it's possible that one or more fields are NULL. In such cases:

• If all non-NULL field values are equal, the comparison returns NULL.
• If any non-NULL field values are not equal, the comparison returns false.

The following table demonstrates how STRUCT data types are compared when they have fields that are NULL valued.

Struct1	Struct2	Struct1 = Struct2
STRUCT(1, NULL)	STRUCT(1, NULL)	NULL
STRUCT(1, NULL)	STRUCT(2, NULL)	FALSE
STRUCT(1,2)	STRUCT(1, NULL)	NULL

IS operators

IS operators return TRUE or FALSE for the condition they are testing. They never return NULL, even for NULL inputs. If NOT is present, the output BOOL value is inverted.

Function Syntax	Input Data Type	Result Data Type	Description
X IS [NOT] NULL	Any value type	BOOL	Returns TRUE if the operand X evaluates to NULL, and returns FALSE otherwise.
X IS [NOT] TRUE	BOOL	BOOL	Returns TRUE if the BOOL operand evaluates to TRUE. Returns FALSE otherwise.
X IS [NOT] FALSE	BOOL	BOOL	Returns TRUE if the BOOL operand evaluates to FALSE. Returns FALSE otherwise.