SubField - 指令碼與圖表函數

SubField() 用來從上層字串欄位中擷取子字串元件，其中原始記錄欄位包含兩個或多個部分，以分隔符號分隔。

可以使用 Subfield() 函數，例如，為了從包含完整名稱的記錄清單中擷取名字和暱稱、路徑名稱的元件部分，或者從逗點分隔的表格中擷取資料。

如果您在 LOAD 陳述式中使用 Subfield() 函數，並且省略選用 field_no 參數，將針對每一個子字串產生一筆完整記錄。如果使用 Subfield() 載入數個欄位，則會建立所有組合的 Cartesian 產品。

語法：

SubField(text, delimiter[, field_no ])

傳回的資料類型：字串

引數：

引數
引數	描述
text	原始字串。這可以是硬式編碼文字、變數、貨幣符號展開或其他運算式。
delimiter	輸入 text 內將字串分為元件部分的字元。
field_no	選用第三引數是一個整數，指定要傳回上層字串 text 中的哪個子字串。使用值 1 可傳回第一個子字串，使用值 2 可傳回第二個子字串，以此類推。若 field_no 為正值，會從左至右擷取子字串。若 field_no 為負值，會從右至左擷取子字串。

可以使用 SubField()，來取代函數的複雜組合 (例如 Len()、Right()、Left()、Mid() 及其他字串函數)。

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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