📅 最后修改于: 2020-12-25 05:03:28 🧑 作者: Mango
XQuery 1.0，XPath 2.0和XSLT 2.0共享相同的函数库。
一系列不同类型的XQuery函数：
函数以fn：前缀指定。例如：fn：字符串()。但是fn：是名称空间的默认前缀，因此在函数时不必为前缀fn。
| Index | Name | Description |
|---|---|---|
| 1) | fn:node-name(node) | It is used to return the node-name of the argument node. |
| 2) | fn:nilled(node) | It is used to return a Boolean value indicating whether the argument node is nil. |
| 3) | fn:data(item.item,…) | It is used to take a sequence of items and return a sequence of atomic values. |
| 4) | fn:base-uri() fn:base-uri(node) |
It returns the value of the base-uri property of the current or specified node. |
| 5) | fn:document-uri(node) | It returns the value of the document-uri property for the specified node. |
| Index | Name | Description |
|---|---|---|
| 1) | fn:error() fn:error(error) fn:error(error,description) fn:error(error,description,error-object) |
Example: error(fn:qname(‘http://example.com/test’, ‘err:toohigh’), ‘error: price is too high’)result: returns http://example.com/test#toohigh and the string “error: price is too high” to the external processing environment. |
| 2) | fn:trace(value,label) | it is used to debug queries. |
| Index | Name | Description |
|---|---|---|
| 1) | fn:abs(num) | It returns the absolute value of the argument. For example: abs(3.14) Result: 3.14 |
| 2) | fn:abs(num) | It returns the absolute value of the argument For example: abs(3.14) Result: 3.14 Example: abs(-3.14) Result: 3.14 |
| 3) | fn:ceiling(num) | It returns the smallest integer that is greater than the number argument For example: ceiling(3.14) Result: 4 |
| 4) | fn:floor(num) | It returns the largest integer that is not greater than the number argument For example: floor(3.14) Result: 3 |
| 5) | fn:round(num) | It is used to round of the number argument to the nearest integer For example: round(3.14) Result: 3 |
| 6) | fn:round-half-to-even() | Example: round-half-to-even(0.5) Result: 0 Example: round-half-to-even(1.5) Result: 2 Example: round-half-to-even(2.5) Result: 2 |
XQuery中使用了很多字符串函数，但是这里我们使用的是选定的函数。
XQuery的常用字符串操作功能列表：
| Index | Name | Description |
|---|---|---|
| 1) | string-length($string as xs:string) as xs:integer | It returns the length of the string. |
| 2) | concat($input as xs:anyatomictype?) as xs:string | It returns the concatenated string as output. |
| 3) | string-join($sequence as xs:string*, $delimiter as xs:string) as xs:string | It returns the combination of items in a sequence separated by a delimiter. |
| Index | Name | Description |
|---|---|---|
| 1) | fn:boolean(arg) | It is used to return a Boolean value for a number, string, or node-set. |
| 2) | fn:not(arg) | It specifies that the argument is first reduced to a Boolean value by applying the Boolean() function. It returns true if the Boolean value is false, and false if the Boolean value is true. For example: not(true()) Result: false |
| 3) | fn:true() | It returns the Boolean value true Example: true() Result: true |
| 4) | fn:false() | It returns the Boolean value false For example: false() Result: false |
XQuery支持很多时间和日期函数，但是在这里，我们提供所选的功能。
XQuery提供的一些常用日期和时间函数的列表：
| Index | Name | Description |
|---|---|---|
| 1) | current-date() | It is used to return the current date. |
| 2) | current-time() | It is used to return the current time. |
| 3) | current-datetime() | It is used to return both the current date and the current time. |