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# Beam SQL: Scalar functions

Beam SQL has implemented the following built-in functions See also [Calcite
SQL's operators and functions
reference](http://calcite.apache.org/docs/reference.html#operators-and-functions)

## Comparison functions and operators

| Operator syntax | Description |
| ---- | ---- |
| value1 = value2 | Equals |
| value1 <> value2 | Not equal |
| value1 > value2 | Greater than |
| value1 >= value2 | Greater than or equal |
| value1 < value2 | Less than |
| value1 <= value2 | Less than or equal |
| value IS NULL | Whether value is null |
| value IS NOT NULL | Whether value is not null |
{:.table}

## Logical functions and operators

| Operator syntax | Description |
| ---- | ---- |
| boolean1 OR boolean2 | Whether boolean1 is TRUE or boolean2 is TRUE |
| boolean1 AND boolean2 | Whether boolean1 and boolean2 are both TRUE |
| NOT boolean | Whether boolean is not TRUE; returns UNKNOWN if boolean is UNKNOWN |
{:.table}

## Arithmetic expressions

| Operator syntax | Description|
| ---- | ---- |
| numeric1 + numeric2 | Returns numeric1 plus numeric2|
| numeric1 - numeric2 | Returns numeric1 minus numeric2|
| numeric1 * numeric2 | Returns numeric1 multiplied by numeric2|
| numeric1 / numeric2 | Returns numeric1 divided by numeric2|
| MOD(numeric, numeric) | Returns the remainder (modulus) of numeric1 divided by numeric2. The result is negative only if numeric1 is negative|
{:.table}

## Math functions

| Operator syntax | Description |
| ---- | ---- |
| ABS(numeric) | Returns the absolute value of numeric |
| SQRT(numeric) | Returns the square root of numeric |
| LN(numeric) | Returns the natural logarithm (base e) of numeric |
| LOG10(numeric) | Returns the base 10 logarithm of numeric |
| EXP(numeric) | Returns e raised to the power of numeric |
| ACOS(numeric) | Returns the arc cosine of numeric |
| ASIN(numeric) | Returns the arc sine of numeric |
| ATAN(numeric) | Returns the arc tangent of numeric |
| COT(numeric) | Returns the cotangent of numeric |
| DEGREES(numeric) | Converts numeric from radians to degrees |
| RADIANS(numeric) | Converts numeric from degrees to radians |
| SIGN(numeric) | Returns the signum of numeric |
| SIN(numeric) | Returns the sine of numeric |
| TAN(numeric) | Returns the tangent of numeric |
| ROUND(numeric1, numeric2) | Rounds numeric1 to numeric2 places right to the decimal point |
{:.table}

## Date functions

| Operator syntax | Description |
| ---- | ---- |
| LOCALTIME | Returns the current date and time in the session time zone in a value of datatype TIME |
| LOCALTIME(precision) | Returns the current date and time in the session time zone in a value of datatype TIME, with precision digits of precision |
| LOCALTIMESTAMP | Returns the current date and time in the session time zone in a value of datatype TIMESTAMP |
| LOCALTIMESTAMP(precision) | Returns the current date and time in the session time zone in a value of datatype TIMESTAMP, with precision digits of precision |
| CURRENT_TIME | Returns the current time in the session time zone, in a value of datatype TIMESTAMP WITH TIME ZONE |
| CURRENT_DATE | Returns the current date in the session time zone, in a value of datatype DATE |
| CURRENT_TIMESTAMP | Returns the current date and time in the session time zone, in a value of datatype TIMESTAMP WITH TIME ZONE |
| EXTRACT(timeUnit FROM datetime) | Extracts and returns the value of a specified datetime field from a datetime value expression |
| FLOOR(datetime TO timeUnit) | Rounds datetime down to timeUnit |
| CEIL(datetime TO timeUnit) | Rounds datetime up to timeUnit |
| YEAR(date) | Equivalent to EXTRACT(YEAR FROM date). Returns an integer. |
| QUARTER(date) | Equivalent to EXTRACT(QUARTER FROM date). Returns an integer between 1 and 4. |
| MONTH(date) | Equivalent to EXTRACT(MONTH FROM date). Returns an integer between 1 and 12. |
| WEEK(date) | Equivalent to EXTRACT(WEEK FROM date). Returns an integer between 1 and 53. |
| DAYOFYEAR(date) | Equivalent to EXTRACT(DOY FROM date). Returns an integer between 1 and 366. |
| DAYOFMONTH(date) | Equivalent to EXTRACT(DAY FROM date). Returns an integer between 1 and 31. |
| DAYOFWEEK(date) | Equivalent to EXTRACT(DOW FROM date). Returns an integer between 1 and 7. |
| HOUR(date) | Equivalent to EXTRACT(HOUR FROM date). Returns an integer between 0 and 23. |
| MINUTE(date) | Equivalent to EXTRACT(MINUTE FROM date). Returns an integer between 0 and 59. |
| SECOND(date) | Equivalent to EXTRACT(SECOND FROM date). Returns an integer between 0 and 59. |
{:.table}

## String functions

| Operator syntax | Description |
| ---- | ---- |
| string \|\| string | Concatenates two character strings |
| CHAR_LENGTH(string) | Returns the number of characters in a character string |
| CHARACTER_LENGTH(string) | As CHAR_LENGTH(string) |
| UPPER(string) | Returns a character string converted to upper case |
| LOWER(string) | Returns a character string converted to lower case |
| POSITION(string1 IN string2) | Returns the position of the first occurrence of string1 in string2 |
| POSITION(string1 IN string2 FROM integer) | Returns the position of the first occurrence of string1 in string2 starting at a given point (not standard SQL) |
| TRIM( { BOTH \| LEADING \| TRAILING } string1 FROM string2) | Removes the longest string containing only the characters in string1 from the start/end/both ends of string1 |
| OVERLAY(string1 PLACING string2 FROM integer [ FOR integer2 ]) | Replaces a substring of string1 with string2 |
| SUBSTRING(string FROM integer) | Returns a substring of a character string starting at a given point |
| SUBSTRING(string FROM integer FOR integer) | Returns a substring of a character string starting at a given point with a given length |
| INITCAP(string) | Returns string with the first letter of each word converter to upper case and the rest to lower case. Words are sequences of alphanumeric characters separated by non-alphanumeric characters. |
{:.table}

## Conditional functions

| Operator syntax | Description |
| ---- | ---- |
| CASE value <br>WHEN value1 [, value11 ]* THEN result1 <br>[ WHEN valueN [, valueN1 ]* THEN resultN ]* <br>[ ELSE resultZ ] <br>END | Simple case |
| CASE <br>WHEN condition1 THEN result1 <br>[ WHEN conditionN THEN resultN ]* <br>[ ELSE resultZ ] <br>END | Searched case |
| NULLIF(value, value) | Returns NULL if the values are the same. For example, NULLIF(5, 5) returns NULL; NULLIF(5, 0) returns 5. |
| COALESCE(value, value [, value ]*) | Provides a value if the first value is null. For example, COALESCE(NULL, 5) returns 5. |
{:.table}
