📅  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) |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |