You must DECLARE a new variable instead of using SET to update an existing one. In addition, SET cannot be used to update user variables. Unlike T-SQL, a variable must be declared and initialized in the same statement. DECLARE string = "overwritten declaration" ĭECLARE EXTERNAL string = "external = SELECT * FROM AS T(x) This allows users to parameterize scripts with a default and allows tools (such as Azure Data Factory) to provide a parameter model and overwrite the default parameter values. The following script on the other hand will produce the file with the content "overwritten declaration". OUTPUT TO "/output/test.csv" USING Outputters.Csv()
REFERENCE ASSEMBLY myassembly ĭECLARE string = "string "+() ĭECLARE EXTERNAL DECLARE EXTERNAL allows the declaration of a script scalar expression variable that can be overwritten by a previous DECLARE statement without failing compilation.įor example, the following script will produce the specified file with content "external declaration": DECLARE EXTERNAL string = "external = SELECT * FROM AS T(x) DECLARE string = ("Seat"+ "tle").ToUpper() Ĭustom assembly objects, such as c# user-defined functions, can be referenced inside a DECLARE statement. You can even call limited set of methods that can be constant-folded. You can use C# Expressions to compute values DECLARE string = "Seat" + "tle" You can do more than store simple values. When you declare a variable, you should also initialize it. Declaration tells the compiler about the existence of an entity in the program and its location.
A simple example should illustrate how this works: DECLARE string = "Seattle" Declaration of a variable in a computer programming language is a statement used to specify the variable name and its data type.
Variables allow you to name scalar and rowset expressions. System_Variable := := Unquoted_Identifier. The DECLARE statement initializes a U-SQL variable.
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