As the name suggests: table-valued returns table, however Scalar-valued returns a single value, such as a string, integer, or bit value. 1、table-valued function As to create table-valued function, there are 2 ways, look at the example below please, it’s suitable for simple logic: USE...
Implementing table valued functions in Transact-SQL is easy: create function t_sql_tvfPoints() returns @points table (x float, y float) as begin insert @points values(1,2); insert @points values(3,4); return; end This is fine if your function can be done entirely in Transact-SQL. Bu...
在MyUDTF中继承了TableFunction<T>, 所有的自定义表函数都必须继承该抽象类,其中T表示返回的数据类型,通常如果是原子类型则直接指定例如String, 如果是复合类型通常会选择Row, FlinkSQL 通过类型提取可以自动识别返回的类型,如果识别不了需要重载其getResultType方法,指定其返回的TypeInformation,重点看下eval 方法定义: ...
在Flink SQL中使用TableFunction需要搭配LATERAL TABLE一起使用,将其认为是一张虚拟的表,整个过程就是一个Join with Table Function过程,左表(tbl1) 会join 右表(t1) 的每一条记录。但是也存在另外一种情况右表(t1)没有输出但是也需要左表输出那么可以使用LEFT JOIN LATERAL TABLE,用法如下: 代码语言:javascript...
Public Shared Sub FillRow ( <Out()> ByRef value As SqlInt32) Define a table-valued function in Transact-SQL The syntax for defining a CLR table-valued function is similar to that of a Transact-SQL table-valued function, with the addition of the EXTERNAL NAME clause. For example: SQL ...
A parameter defines the name of the parameter in form of a variable local to the function body. Its type is either a built-in U-SQL type, which optionally can be initialized with a default value, or a named or anonymous table type: Syntax Parameter := User_Variable ( Type_...
今天我们来聊聊flink sql中另外一种自定义函数-TableFuntion. TableFuntion 可以有0个、一个、多个输入参数,他的返回值可以是任意行,每行可以有多列数据. 实现自定义TableFunction需要继承TableFunction类,然后定义一个public类型的eval方法。结合官网的例子具体来讲解一下。 自定义函数 单个eval方法 代码语言:javascript...
Any expression passed to a TVF argument will be inlined in the function’s body. This means that non-deterministic expressions are not made deterministic by U-SQL; they will still be non-deterministic if they are invoked more than once by the final query. Argument expressions are lim...
Learn more about the Microsoft.SqlServer.Management.SqlParser.SqlCodeDom.SqlTableValuedFunctionRefExpression.Arguments in the Microsoft.SqlServer.Management.SqlParser.SqlCodeDom namespace.
{"devid":"dev01","time":1574944573000,"data":[{"type":"temperature","value":"10"},{"type":"battery","value":"1"}]} 1. 得到结果: 3>(true,dev01,1574944573000,temperature,10)3>(true,dev01,1574944573000,battery,1) 1. 至此拿到了符合要求的数据。在Flink SQL中使用TableFunction需要搭配LA...