Operators

• Unary and Binary Operators
• Operator Precedence
• Arithmetic Operators
• String Operators
• Comparsion Operators
• Logical Operators
• Set Operators

You can perform arithmetic operations in expressions by using operators. Operators can be used for calculation, value comparison or to assign values.

Unary and Binary Operators

Table 10. Unary and binary operators

Operator	Operation	Format	Description
Unary	A unary operator applies to one operand or a single value expression.	operator operand	unary plus operator(+) unary negation operator(-) logical negation(NOT)
Binary	Binary A binary operator applies to two operands or two value expressions.	operand1 operator operand2	multiplicative operators ( *, / ) additive operators ( +,- ) comparison operators ( =,!=,<,>,<=,>=) logical operators ( AND, OR )

Operator Precedence

An expression can use several operators. If the number of operators is greater than one then the SAP HANA Database will evaluate them in order of operator precedence. You can change the order of evaluation by using parentheses, as expressions contained within parentheses are always evaluated first.

If parentheses are not used, the operators have the precedence indicated by the table below. Please note, the SAP HANA Database will evaluate operators with equal precedence from left to right within an expression.

Table 11. SQL operator precedence

Precedence	Operator	Operation
Highest	()	parentheses
	+, -	unary positive and negative operation
	*, /	multiplication, division
	+, -	addition, subtraction
	||	concatenation
	=, !=, <, >, <=, >=, IS NULL, LIKE, BETWEEN	comparsion
	NOT	logical negation
	AND	conjunction
Lowest	OR	disjunction

Arithmetic Operators

You use arithmetic operators to perform mathematical operations such as adding, subtracting, multiplying, dividing and negation of numeric values.

Table 12. Arithmetic operators

Operator	Description
-<expression>	Negation. If the expression is the NULL value, the result is NULL.
<expression> + <expression>	Addition. If either expression is the NULL value, the result is NULL.
<expression> - <expression>	Subtraction. If either expression is the NULL value, the result is NULL.
<expression> * <expression>	Multiplication. If either expression is NULL, the result is NULL.
<expression> / <expression>	Division. If either expression is NULL, or if the second expression is 0, an error is returned.

String Operators

A concatenation operator combines two items such as strings, expressions or constants into one.

Table 13. Concatenation operators

Operator	Description
<expression> || <expression>	String concatenation (two vertical bars). If either string is NULL, it returns NULL.

For VARCHAR or NVARCHAR type strings, leading or trailing spaces are kept. If either string is of data type NVARCHAR, the result has data type NVARCHAR and is limited to 5000 characters. The maximum length for VARCHAR concatenation is also limited to 5000 characters.

Comparsion Operators

Syntax:

<comparison_operation> ::= <expression1> <comparison_operator> <expression2> 

Table 14. Comparison operators

Operator	Description	Example
=	Equal to	SELECT * FROM students WHERE id = 25;
>	Greater than	SELECT * FROM students WHERE id > 25;
<	Less than	SELECT * FROM students WHERE id < 25;
>=	Greater than or equal to	SELECT * FROM students WHERE id >= 25;
<=	Less than or equal to	SELECT * FROM students WHERE id <= 25;
!=, <>	Not equal	SELECT * FROM students WHERE id != 25; SELECT * FROM students WHERE id <> 25;

Logical Operators

Search conditions can be combined using AND or OR operators. You can also negate them using the NOT operator.

Table 15. Logical operators

Operator	Syntax	Description
AND	WHERE condition1 AND condition2	When using AND, the combined condition is TRUE if both conditions are TRUE, FALSE if either condition is FALSE, and UNKNOWN otherwise.
OR	WHERE condition1 OR condition2	When using OR, the combined condition is TRUE if either condition is TRUE, FALSE if both conditions are FALSE, and UNKNOWN otherwise.
NOT	WHERE NOT condition	The NOT operator is placed before a condition to negate the condition. The NOT condition is TRUE if condition is FALSE, FALSE if condition is TRUE, and UNKNOWN if condition is UNKNOWN.

Set Operators

The operators described in this section perform set operations on the results of two or more queries.

Table 16. Set operators

Operator	Returned Value
UNION	Combines the results of two or more select statements or query expressions
UNION ALL	Combines the results of two or more select statements or query expressions, including all duplicate rows.
INTERSECT	Combines the results of two or more select statements or query expressions, and returns all common rows.
EXCEPT	Takes output from the first query and then removes rows selected by the second query.