{"id":44508,"date":"2018-12-07T12:45:00","date_gmt":"2018-12-07T07:15:00","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=44508"},"modified":"2018-12-06T17:45:44","modified_gmt":"2018-12-06T12:15:44","slug":"qlik-sense-script-syntax","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/qlik-sense-script-syntax\/","title":{"rendered":"Qlik Sense Script Syntax – Backus-Naur Formalism"},"content":{"rendered":"

1. Objective<\/span><\/h2>\n

In our last session, we discussed Qlik Sense Visualization Expression<\/strong><\/a>. Today, we will see Qlik Sense Script Syntax. In this lesson, we are going to learn about how data tables are loaded or written in the data load script of Qlik Sense. Also, we will start with understanding the standard script notation (BNF) which is followed to write codes in the script. Moreover, we will see what types of script statements and keywords are used in the script and how to the script expression is written.<\/span><\/p>\n

So, let’s start the Qlik Sense Script Syntax Tutorial.<\/p>\n

\"Qlik<\/a>

Qlik Sense Script Syntax – Backus-Naur Formalism<\/p><\/div>\n

2. What is Qlik Sense Script Syntax?<\/span><\/h2>\n

In a data load script, various operations are performed for which script statements and keywords are required. The script code should be written in such a format or notation which is correct and readable for the machine. The script statements are executed consecutively if the code syntax is error free. You must always remember to end a script statement or each code line with a semicolon \u2018<\/span>;<\/b>\u2019 The operations performed through a script are, establishing a data connection, loading a data table, loading field names, and values, etc.<\/span><\/p>\n

Recommended Reading –<\/strong> Qlik Sense Logical Functions<\/a><\/strong><\/p>\n

A certain initial piece of code is generated upon creating of a new file, setting up all the basic properties like number interpretation variables, formats etc. The two main keywords used for loading data are LOAD and SELECT. Under the LOAD statement, you can use expressions and functions to manipulate data as you like. <\/span><\/p>\n

3. What is Backus-Naur Formalism?<\/span><\/h2>\n

Backus-Naur Form is a metalanguage. Metalanguages are the languages which are used to explain other natural or computer languages. Any metalanguage follows a specific notation technique or meta syntax through which rules of a language are defined and explained. In the world of computing, there are several widely used metalanguages are <\/span>Backus-Naur Form (BNF),<\/span><\/i> Extended Backus-Naur Form (EBNF)<\/span><\/i>, <\/span>Augmented Backus-Naur Form (ABNF).<\/span><\/i><\/p>\n

Formulating a language for computers in a well-defined and formatted structure is very important for the language to be properly converted into a machine language during execution.<\/span><\/p>\n

Let’s discuss Qlik Sense Mapping function<\/a><\/strong><\/p>\n

The Backus-Naur Form is designed in a specific way with a set of derivation rules expressed as,<\/span><\/p>\n

<symbol> ::= __expression__<\/pre>\n
Every BNF statement follows this rule, where the Symbol is a value defined using \u2018::=\u2019 sign and the __expression__ are the possible and valid variables that can taken up for the defined value. Let us understand this by dividing the above statement into a right half and a left half. The right half has a Non-terminal value and the left half has Terminal values. <\/span><\/p>\n
a. Non-Terminals\u00a0<\/strong>–<\/strong> The Non-terminals are syntactic or lexical entities that are used to define a symbol to be used in a language abiding the formal grammar rules. These are always enclosed in <>. <\/span><\/p>\n
b. Terminals\u00a0<\/strong>–<\/strong> The Terminals are symbols\/values that are the probable outcomes of the defined (non-terminal entity\/symbol) as per the rule. These values are not susceptible to change by the rule.<\/span><\/p>\n
In an expression, let\u2019s suppose that we are defining an entity <digit> then on the right side of the expression will be all the terminal values i.e. the possible values that can be taken up by the system as Digits like 0,1,2,3.. etc. <\/span><\/p>\n
\"Script<\/a>
Script Syntax – Backus Naur Formalism<\/p><\/div>\n
The values or symbol sequences defined on the right are separated by \u201c|\u201d, in case of more than one values. A Non-Terminal can also be defined in or replaced by one or more Non-Terminals on the right side. For instance, if after defining <digits> we want to define <integer> we can do it by creating a rule so that integer is replaced by one or more digits.<\/span><\/p>\n
Have a look at Qlik Sense Null Functions<\/a><\/strong><\/p>\n
<integer> ::= <digit> | <digit><digit><\/pre>\n
Here, both <integer> and <digit> are Non-Terminals and will give an output like,<\/span><\/p>\n
<integer> ::= 5\r\n<integer> ::= 86<\/pre>\n
4. Script Statements and Keywords<\/span><\/h2>\n
The script statements and keywords are the words or characters whose purpose or operation is pre-defined in the script. There is a total of three types of script statements, i.e. script regular statements, script control statements, and script prefixes. <\/span><\/p>\n
a.<\/strong> The <\/span>script regular statements<\/span><\/i> are used to manipulate data in some general ways. You can apply these statements over numerous code lines. You must always end a script regular statement with a semicolon \u2018<\/span>;<\/b>\u2019. Given below, are all the script regular functions used in Qlik Sense script.<\/span><\/p>\n