Mathematical Operation Functions¶
Relational Operators¶
All data types can be compared by using relational operators and the result is returned as a BOOLEAN value.
Relationship operators are binary operators. Two compared data types must be of the same type or they must support implicit conversion.
Table 1 lists all relational operators supported by Flink SQL.
Operator | Returned Data Type | Description |
|---|---|---|
A = B | BOOLEAN | If A is equal to B, then TRUE is returned. Otherwise, FALSE is returned. This operator is used for value assignment. |
A <> B | BOOLEAN | If A is not equal to B, then TRUE is returned. Otherwise, FALSE is returned. If A or B is NULL, then NULL is returned. This operator follows the standard SQL syntax. |
A < B | BOOLEAN | If A is less than B, then TRUE is returned. Otherwise, FALSE is returned. If A or B is NULL, then NULL is returned. |
A <= B | BOOLEAN | If A is less than or equal to B, then TRUE is returned. Otherwise, FALSE is returned. If A or B is NULL, then NULL is returned. |
A > B | BOOLEAN | If A is greater than B, then TRUE is returned. Otherwise, FALSE is returned. If A or B is NULL, then NULL is returned. |
A >= B | BOOLEAN | If A is greater than or equal to B, then TRUE is returned. Otherwise, FALSE is returned. If A or B is NULL, then NULL is returned. |
A IS NULL | BOOLEAN | If A is NULL, then TRUE is returned. Otherwise, FALSE is returned. |
A IS NOT NULL | BOOLEAN | If A is not NULL, then TRUE is returned. Otherwise, FALSE is returned. |
A IS DISTINCT FROM B | BOOLEAN | If A is not equal to B, TRUE is returned. NULL indicates A equals B. |
A IS NOT DISTINCT FROM B | BOOLEAN | If A is equal to B, TRUE is returned. NULL indicates A equals B. |
A BETWEEN [ASYMMETRIC | SYMMETRIC] B AND C | BOOLEAN | If A is greater than or equal to B but less than or equal to C, TRUE is returned.
|
A NOT BETWEEN B [ASYMMETRIC | SYMMETRIC]AND C | BOOLEAN | If A is less than B or greater than C, TRUE is returned.
|
A LIKE B [ ESCAPE C ] | BOOLEAN | If A matches pattern B, TRUE is returned. The escape character C can be defined as required. |
A NOT LIKE B [ ESCAPE C ] | BOOLEAN | If A does not match pattern B, TRUE is returned. The escape character C can be defined as required. |
A SIMILAR TO B [ ESCAPE C ] | BOOLEAN | If A matches regular expression B, TRUE is returned. The escape character C can be defined as required. |
A NOT SIMILAR TO B [ ESCAPE C ] | BOOLEAN | If A does not match regular expression B, TRUE is returned. The escape character C can be defined as required. |
value IN (value [, value]* ) | BOOLEAN | If the value is equal to any value in the list, TRUE is returned. |
value NOT IN (value [, value]* ) | BOOLEAN | If the value is not equal to any value in the list, TRUE is returned. |
EXISTS (sub-query) | BOOLEAN | If sub-query returns at least one row, TRUE is returned. |
value IN (sub-query) | BOOLEAN | If value is equal to a row returned by subquery, TRUE is returned. |
value NOT IN (sub-query) | BOOLEAN | If value is not equal to a row returned by subquery, TRUE is returned. |
Precautions
Values of the double, real, and float types may be different in precision. The equal sign (=) is not recommended for comparing two values of the double type. You are advised to obtain the absolute value by subtracting these two values of the double type and determine whether they are the same based on the absolute value. If the absolute value is small enough, the two values of the double data type are regarded equal. For example:
abs(0.9999999999 - 1.0000000000) < 0.000000001 //The precision decimal places of 0.9999999999 and 1.0000000000 are 10, while the precision decimal place of 0.000000001 is 9. Therefore, 0.9999999999 can be regarded equal to 1.0000000000.
Comparison between data of the numeric type and character strings is allowed. During comparison using relational operators, including >, <, <=, and >=, data of the string type is converted to numeric type by default. No characters other than numeric characters are allowed.
Character strings can be compared using relational operators.
Logical Operators¶
Common logical operators are AND, OR, and NOT. Their priority order is NOT > AND > OR.
Table 2 lists the calculation rules. A and B indicate logical expressions.
Operator | Returned Data Type | Description |
|---|---|---|
A OR B | BOOLEAN | If A or B is TRUE, TRUE is returned. Three-valued logic is supported. |
A AND B | BOOLEAN | If both A and B are TRUE, TRUE is returned. Three-valued logic is supported. |
NOT A | BOOLEAN | If A is not TRUE, TRUE is returned. If A is UNKNOWN, UNKNOWN is returned. |
A IS FALSE | BOOLEAN | If A is TRUE, TRUE is returned. If A is UNKNOWN, FALSE is returned. |
A IS NOT FALSE | BOOLEAN | If A is not FALSE, TRUE is returned. If A is UNKNOWN, TRUE is returned. |
A IS TRUE | BOOLEAN | If A is TRUE, TRUE is returned. If A is UNKNOWN, FALSE is returned. |
A IS NOT TRUE | BOOLEAN | If A is not TRUE, TRUE is returned. If A is UNKNOWN, TRUE is returned. |
A IS UNKNOWN | BOOLEAN | If A is UNKNOWN, TRUE is returned. |
A IS NOT UNKNOWN | BOOLEAN | If A is not UNKNOWN, TRUE is returned. |
Precautions
Only data of the Boolean type can be used for calculation using logical operators. Implicit type conversion is not supported.
Arithmetic Operators¶
Arithmetic operators include binary operators and unary operators, for all of which, the returned results are of the numeric type. Table 3 lists arithmetic operators supported by Flink SQL.
Operator | Returned Data Type | Description |
|---|---|---|
| All numeric types | Returns numbers. |
| All numeric types | Returns negative numbers. |
A + B | All numeric types | A plus B. The result type is associated with the operation data type. For example, if floating-point number is added to an integer, the result will be a floating-point number. |
A - B | All numeric types | A minus B. The result type is associated with the operation data type. |
A * B | All numeric types | Multiply A and B. The result type is associated with the operation data type. |
A / B | All numeric types | Divide A by B. The result is a number of the double type (double-precision number). |
POWER(A, B) | All numeric types | Returns the value of A raised to the power B. |
ABS(numeric) | All numeric types | Returns the absolute value of a specified value. |
MOD(A, B) | All numeric types | Returns the remainder (modulus) of A divided by B. A negative value is returned only when A is a negative value. |
SQRT(A) | All numeric types | Returns the square root of A. |
LN(A) | All numeric types | Returns the nature logarithm of A (base e). |
LOG10(A) | All numeric types | Returns the base 10 logarithms of A. |
LOG2(A) | All numeric types | Returns the base 2 logarithm of A. |
LOG(B) LOG(A, B) | All numeric types | When called with one argument, returns the natural logarithm of B. When called with two arguments, this function returns the logarithm of B to the base A. B must be greater than 0 and A must be greater than 1. |
EXP(A) | All numeric types | Return the value of e raised to the power of a. |
CEIL(A) CEILING(A) | All numeric types | Return the smallest integer that is greater than or equal to a. For example: ceil(21.2) = 22. |
FLOOR(A) | All numeric types | Return the largest integer that is less than or equal to a. For example: floor(21.2) = 21. |
SIN(A) | All numeric types | Returns the sine value of A. |
COS(A) | All numeric types | Returns the cosine value of A. |
TAN(A) | All numeric types | Returns the tangent value of A. |
COT(A) | All numeric types | Returns the cotangent value of A. |
ASIN(A) | All numeric types | Returns the arc sine value of A. |
ACOS(A) | All numeric types | Returns the arc cosine value of A. |
ATAN(A) | All numeric types | Returns the arc tangent value of A. |
ATAN2(A, B) | All numeric types | Returns the arc tangent of a coordinate (A, B). |
COSH(A) | All numeric types | Returns the hyperbolic cosine of A. Return value type is DOUBLE. |
DEGREES(A) | All numeric types | Convert the value of a from radians to degrees. |
RADIANS(A) | All numeric types | Convert the value of a from degrees to radians. |
SIGN(A) | All numeric types | Returns the sign of A. 1 is returned if A is positive. -1 is returned if A is negative. Otherwise, 0 is returned. |
ROUND(A, d) | All numeric types | Returns a number rounded to d decimal places for A. For example: round(21.263,2) = 21.26. |
PI | All numeric types | Returns the value of pi. |
E() | All numeric types | Returns the value of e. |
RAND() | All numeric types | Returns a pseudorandom double value in the range [0.0, 1.0) |
RAND(A) | All numeric types | Returns a pseudorandom double value in the range [0.0, 1.0) with an initial seed A. Two RAND functions will return identical sequences of numbers if they have the same initial seed. |
RAND_INTEGER(A) | All numeric types | Returns a pseudorandom double value in the range [0.0, A) |
RAND_INTEGER(A, B) | All numeric types | Returns a pseudorandom double value in the range [0.0, B) with an initial seed A. |
UUID() | All numeric types | Returns a UUID string. |
BIN(A) | All numeric types | Returns a string representation of integer A in binary format. Returns NULL if A is NULL. |
HEX(A) HEX(B) | All numeric types | Returns a string representation of an integer A value or a string B in hex format. Returns NULL if the argument is NULL. |
TRUNCATE(A, d) | All numeric types | Returns a number of truncated to d decimal places. Returns NULL if A or d is NULL. Example: truncate (42.345, 2) = 42.340 truncate(42.345) = 42.000 |
PI() | All numeric types | Returns the value of pi. |
Precautions
Data of the string type is not allowed in arithmetic operations.