SubField - 脚本和图表函数

SubField() 用于从父字符串字段提取子字符串组成部分，其中原始记录字段由两个或更多用分隔符分隔的部分构成。

Subfield() 函数可用于（例如）从由全名、路径名的组成部分构成的记录的列表中提取名字和姓氏，或用于从逗号分隔的表格中提取数据。

如果在忽略可选 field_no 参数的 LOAD 语句中使用 Subfield() 函数，则会为每个子字符串生成一个完整记录。如果使用 Subfield() 加载多个字段，则会创建所有组合的 Cartesian 产品。

语法：

SubField(text, delimiter[, field_no ])

返回数据类型：字符串

参数：

参数
参数	说明
text	原始字符串。可以是硬编码文本、变量、货币符号扩展或其他表达式。
delimiter	输入 text 中将字符串分成各组成部分的字符。
field_no	可选的第三个参数是整数，用于指定返回父字符串 text 的哪些子字符串。使用值 1 可以返回第一个子字符串，使用值 2 可以返回第二个字符串，以此类推。如果 field_no 为正值，子字符串是自左至右提取的。如果 field_no 为负值，子字符串是自右至左提取的。

可以使用 SubField() 代替复杂的函数组合（例如 Len()、Right()、Left()、Mid()）和其他字符串函数。

Examples: Chart expressions
Example	Result
SubField(S, ';' ,2)	Returns 'cde' if S is 'abc;cde;efg'.
SubField(S, ';' ,1)	Returns an empty string if S is an empty string.
SubField(S, ';' ,1)	Returns an empty string if S is ';'.
Suppose you have a variable that holds a path name vMyPath, Set vMyPath=\Users\ext_jrb\Documents\Qlik\Sense\Apps;.	In a text & image chart, you can add a measure such as: SubField(vMyPath, '\',-3), which results in 'Qlik', because it is the substring third from the right-hand end of the variable vMyPath.

Examples: Script and chart expressions using SubField

Basic examples

Example	Result
SubField(S, ';' ,2)	Returns 'cde' if S is 'abc;cde;efg'.
SubField(S, ';' ,1)	Returns an empty string if S is an empty string.
SubField(S, ';' ,1)	Returns an empty string if S is ';'.
Suppose you have a variable that holds a path name vMyPath, Set vMyPath=\Users\ext_jrb\Documents\Qlik\Sense\Apps;.	In a text & image chart, you can add a measure such as: SubField(vMyPath, '\',-3), which results in 'Qlik', because it is the substring third from the right-hand end of the variable vMyPath.

Script example 1

Load script

Load the following script expressions and data in the data load editor.

FullName: 					 LOAD * inline [ Name 'Dave Owen' 'Joe Tem' ];  SepNames:  Load Name, SubField(Name, ' ',1) as FirstName, SubField(Name, ' ',-1) as Surname Resident FullName; Drop Table FullName;

Create a visualization

Create a table visualization in a Qlik Sense sheet with Name, FirstName, and SurName as dimensions.

Result

Name	FirstName	SurName
Dave Owen	Dave	Owen
Joe Tem	Joe	Tem

Explanation

The SubField() function extracts the first substring of Name by setting the field_no argument to 1. Since the value of field_no is positive, a left to right order is followed for extracting the subtring. A second function call extracts the second substring by setting the field_no argument to -1, which extracts the substring following a right to left order.

Script example 2

Load script

Load the following script expressions and data in the data load editor.

LOAD DISTINCT Instrument, SubField(Player,',') as Player, SubField(Project,',') as Project;  Load * inline [ Instrument|Player|Project Guitar|Neil,Mike|Music,Video Guitar|Neil|Music,OST Synth|Neil,Jen|Music,Video,OST Synth|Jo|Music Guitar|Neil,Mike|Music,OST ] (delimiter is '|');

Create a visualization

Create a table visualization in a Qlik Sense sheet with Instrument, Player, and Project as dimensions.

Result

Instrument	Player	Project
Guitar	Mike	Music
Guitar	Mike	Video
Guitar	Mike	OST
Guitar	Neil	Music
Guitar	Neil	Video
Guitar	Neil	OST
Synth	Jen	Music
Synth	Jen	Video
Synth	Jen	OST
Synth	Jo	Music
Synth	Neil	Music
Synth	Neil	Video
Synth	Neil	OST

Explanation

This example shows how using multiple instances of the Subfield() function, each with the field_no parameter left out, from within the same LOAD statement creates Cartesian products of all combinations. The DISTINCT option is used to avoid creating duplicate records.

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