homework-jianmu/docs/en/14-reference/03-taos-sql/16-operators.md

title	description	slug
Operators	All operators supported by TDengine	/tdengine-reference/sql-manual/operators

Arithmetic Operators

#	Operator	Supported Types	Description
1	+, -	Numeric Types	Represents positive and negative numbers, unary operators
2	+, -	Numeric Types	Represents addition and subtraction, binary operators
3	*, /	Numeric Types	Represents multiplication and division, binary operators
4	%	Numeric Types	Represents the modulus operation, binary operator

Bitwise Operators

#	Operator	Supported Types	Description
1	&	Numeric Types	Bitwise AND, binary operator
2	|	Numeric Types	Bitwise OR, binary operator

JSON Operators

The -> operator can be used to access values by key in columns of JSON type. The left side of -> is the column identifier, and the right side is the string constant of the key, such as col->'name', which returns the value of the key 'name'.

Set Operators

Set operators combine the results of two queries into a single result. Queries that include set operators are called compound queries. In a compound query, the corresponding expressions in the select list of each query must match in number, and the result type is determined by the first query; subsequent queries must have result types that can be converted to the first query's result type, with conversion rules similar to the CAST function.

TDengine supports the UNION ALL and UNION operators. UNION ALL merges the result sets returned by the queries without removing duplicates. UNION merges the result sets and removes duplicates. A single SQL statement can support up to 100 set operators.

Comparison Operators

#	Operator	Supported Types	Description
1	=	All types except BLOB, MEDIUMBLOB, and JSON	Equal
2	<>, !=	All types except BLOB, MEDIUMBLOB, and JSON, and cannot be the timestamp primary key column of a table	Not equal
3	>, <	All types except BLOB, MEDIUMBLOB, and JSON	Greater than, less than
4	>=, <=	All types except BLOB, MEDIUMBLOB, and JSON	Greater than or equal to, less than or equal to
5	IS [NOT] NULL	All types	Is null
6	[NOT] BETWEEN AND	All types except BOOL, BLOB, MEDIUMBLOB, JSON, and GEOMETRY	Closed interval comparison
7	IN	All types except BLOB, MEDIUMBLOB, and JSON, and cannot be the timestamp primary key column of a table	Equal to any value in the list
8	NOT IN	All types except BLOB, MEDIUMBLOB, and JSON, and cannot be the timestamp primary key column of a table	Not equal to any value in the list
9	LIKE	BINARY, NCHAR, and VARCHAR	Matches the specified pattern string with wildcards
10	NOT LIKE	BINARY, NCHAR, and VARCHAR	Does not match the specified pattern string
11	MATCH, NMATCH	BINARY, NCHAR, and VARCHAR	Regular expression match
12	CONTAINS	JSON	Whether a key exists in JSON

The LIKE condition uses wildcard strings for matching checks, with the following rules:

• '%' (percent) matches 0 to any number of characters; '_' (underscore) matches any single ASCII character.
• To match the '_' (underscore) character that is naturally present in the string, you can write it as '_' in the wildcard string, escaping it with a backslash.
• The wildcard string cannot exceed 100 bytes in length. It is not recommended to use excessively long wildcard strings, as they may significantly affect the performance of the LIKE operation.

The MATCH and NMATCH conditions use regular expressions for matching, with the following rules:

• Supports regular expressions that conform to POSIX standards. Specifics can be found in Regular Expressions.
• MATCH returns TRUE when it matches the regular expression; NMATCH returns TRUE when it does not match the regular expression.
• Regular expressions can only filter based on subtable names (i.e., tbname) and string-type tag values, and do not support filtering on ordinary columns.
• The length of the regular matching string cannot exceed 128 bytes. The maximum allowed length for the regular matching string can be set and adjusted using the maxRegexStringLen parameter, which is a client configuration parameter that requires restarting the client to take effect.

Logical Operators

#	Operator	Supported Types	Description
1	AND	BOOL	Logical AND; returns TRUE if both conditions are TRUE; returns FALSE if either is FALSE
2	OR	BOOL	Logical OR; returns TRUE if either condition is TRUE; returns FALSE if both are FALSE

TDengine performs short-circuit optimization when evaluating logical conditions: for AND, if the first condition is FALSE, it does not evaluate the second condition and returns FALSE immediately; for OR, if the first condition is TRUE, it does not evaluate the second condition and returns TRUE immediately.