Apache Presto-SQL函数

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📜 Apache Presto-SQL函数

📅 最后修改于: 2020-11-28 13:02:07 🧑 作者: Mango

到目前为止，我们正在讨论在Presto上运行一些简单的基本查询。本章将讨论重要的SQL函数。

数学函数

数学函数对数学公式进行运算。下表详细描述了功能列表。

S.No.	Function & Description
1.	abs(x) Returns the absolute value of x
2.	cbrt(x) Returns the cube root of x
3.	ceiling(x) Returns the x value rounded up to the nearest integer
4.	ceil(x) Alias for ceiling(x)
5.	degrees(x) Returns the degree value for x
6.	e(x) Returns the double value for Euler’s number
7.	exp(x) Returns the exponent value for Euler’s number
8.	floor(x) Returns x rounded down to the nearest integer
9.	from_base(string,radix) Returns the value of string interpreted as a base-radix number
10.	ln(x) Returns the natural logarithm of x
11.	log2(x) Returns the base 2 logarithm of x
12.	log10(x) Returns the base 10 logarithm of x
13.	log(x,y) Returns the base y logarithm of x
14.	mod(n,m) Returns the modulus (remainder) of n divided by m
15.	pi() Returns pi value. The result will be returned as a double value
16.	power(x,p) Returns power of value ‘p’ to the x value
17.	pow(x,p) Alias for power(x,p)
18.	radians(x) converts the angle x in degree radians
19.	rand() Alias for radians()
20.	random() Returns the pseudo-random value
21.	rand(n) Alias for random()
22.	round(x) Returns the rounded value for x
23.	round(x,d) x value rounded for the ‘d’ decimal places
24.	sign(x) Returns the signum function of x, i.e., 0 if the argument is 0 1 if the argument is greater than 0 -1 if the argument is less than 0 For double arguments, the function additionally returns − NaN if the argument is NaN 1 if the argument is +Infinity -1 if the argument is -Infinity
25.	sqrt(x) Returns the square root of x
26.	to_base(x,radix) Return type is archer. The result is returned as the base radix for x
27.	truncate(x) Truncates the value for x
28.	width_bucket(x, bound1, bound2, n) Returns the bin number of x specified bound1 and bound2 bounds and n number of buckets
29.	width_bucket(x, bins) Returns the bin number of x according to the bins specified by the array bins

三角函数

三角函数自变量表示为radians()。下表列出了功能。

S.No	Functions & Description
1.	acos(x) Returns the inverse cosine value(x)
2.	asin(x) Returns the inverse sine value(x)
3.	atan(x) Returns the inverse tangent value(x)
4.	atan2(y,x) Returns the inverse tangent value(y/x)
5.	cos(x) Returns the cosine value(x)
6.	cosh(x) Returns the hyperbolic cosine value(x)
7.	sin(x) Returns the sine value(x)
8.	tan(x) Returns the tangent value(x)
9.	tanh(x) Returns the hyperbolic tangent value(x)

按位函数

下表列出了按位函数。

S.No	Functions & Description
1.	bit_count(x, bits) Count the number of bits
2.	bitwise_and(x,y) Perform bitwise AND operation for two bits, x and y
3.	bitwise_or(x,y) Bitwise OR operation between two bits x, y
4.	bitwise_not(x) Bitwise Not operation for bit x
5.	bitwise_xor(x,y) XOR operation for bits x, y

字符串函数

下表列出了String函数。

S.No	Functions & Description
1.	concat(string1, …, stringN) Concatenate the given strings
2.	length(string) Returns the length of the given string
3.	lower(string) Returns the lowercase format for the string
4.	upper(string) Returns the uppercase format for the given string
5.	lpad(string, size, padstring) Left padding for the given string
6.	ltrim(string) Removes the leading whitespace from the string
7.	replace(string, search, replace) Replaces the string value
8.	reverse(string) Reverses the operation performed for the string
9.	rpad(string, size, padstring) Right padding for the given string
10.	rtrim(string) Removes the trailing whitespace from the string
11.	split(string, delimiter) Splits the string on delimiter and returns an array of size at the most limit
12.	split_part(string, delimiter, index) Splits the string on delimiter and returns the field index
13.	strpos(string, substring) Returns the starting position of the substring in the string
14.	substr(string, start) Returns the substring for the given string
15.	substr(string, start, length) Returns the substring for the given string with the specific length
16.	trim(string) Removes the leading and trailing whitespace from the string

日期和时间功能

下表列出了日期和时间功能。

S.No	Functions & Description
1.	current_date Returns the current date
2.	current_time Returns the current time
3.	current_timestamp Returns the current timestamp
4.	current_timezone() Returns the current timezone
5.	now() Returns the current date,timestamp with the timezone
6.	localtime Returns the local time
7.	localtimestamp Returns the local timestamp

正则表达式函数

下表列出了正则表达式函数。

S.No	Functions & Description
1.	regexp_extract_all(string, pattern) Returns the string matched by the regular expression for the pattern
2.	regexp_extract_all(string, pattern, group) Returns the string matched by the regular expression for the pattern and the group
3.	regexp_extract(string, pattern) Returns the first substring matched by the regular expression for the pattern
4.	regexp_extract(string, pattern, group) Returns the first substring matched by the regular expression for the pattern and the group
5.	regexp_like(string, pattern) Returns the string matches for the pattern. If the string is returned, the value will be true otherwise false
6.	regexp_replace(string, pattern) Replaces the instance of the string matched for the expression with the pattern
7.	regexp_replace(string, pattern, replacement) Replace the instance of the string matched for the expression with the pattern and replacement
8.	regexp_split(string, pattern) Splits the regular expression for the given pattern

JSON函数

下表列出了JSON函数。

S.No	Functions & Description
1.	json_array_contains(json, value) Check the value exists in a json array. If the value exists it will return true, otherwise false
2.	json_array_get(json_array, index) Get the element for index in json array
3.	json_array_length(json) Returns the length in json array
4.	json_format(json) Returns the json structure format
5.	json_parse(string) Parses the string as a json
6.	json_size(json, json_path) Returns the size of the value

URL功能

下表列出了URL函数。

S.No	Functions & Description
1.	url_extract_host(url) Returns the URL’s host
2.	url_extract_path(url) Returns the URL’s path
3.	url_extract_port(url) Returns the URL’s port
4.	url_extract_protocol(url) Returns the URL’s protocol
5.	url_extract_query(url) Returns the URL’s query string

汇总功能

下表列出了汇总功能。

S.No	Functions & Description
1.	avg(x) Returns average for the given value
2.	min(x,n) Returns the minimum value from two values
3.	max(x,n) Returns the maximum value from two values
4.	sum(x) Returns the sum of value
5.	count(*) Returns the number of input rows
6.	count(x) Returns the count of input values
7.	checksum(x) Returns the checksum for x
8.	arbitrary(x) Returns the arbitrary value for x

颜色功能

下表列出了“颜色”功能。

S.No	Functions & Description
1.	bar(x, width) Renders a single bar using rgb low_color and high_color
2.	bar(x, width, low_color, high_color) Renders a single bar for the specified width
3.	color(string) Returns the color value for the entered string
4.	render(x, color) Renders value x using the specific color using ANSI color codes
5.	render(b) Accepts boolean value b and renders a green true or a red false using ANSI color codes
6.	rgb(red, green, blue) Returns a color value capturing the RGB value of three component color values supplied as int parameters ranging from 0 to 255

数组函数

下表列出了Array函数。

S.No	Functions & Description
1.	array_max(x) Finds the max element in an array
2.	array_min(x) Finds the min element in an array
3.	array_sort(x) Sorts the elements in an array
4.	array_remove(x,element) Removes the specific element from an array
5.	concat(x,y) Concatenates two arrays
6.	contains(x,element) Finds the given elements in an array. True will be returned if it is present, otherwise false
7.	array_position(x,element) Find the position of the given element in an array
8.	array_intersect(x,y) Performs an intersection between two arrays
9.	element_at(array,index) Returns the array element position
10.	slice(x,start,length) Slices the array elements with the specific length

Teradata功能

下表列出了Teradata功能。

S.No	Functions & Description
1.	index(string,substring) Returns the index of the string with the given substring
2.	substring(string,start) Returns the substring of the given string. You can specify the start index here
3.	substring(string,start,length) Returns the substring of the given string for the specific start index and length of the string