采用列名作为字符串和默认值。Takes a column name as a string and a default value. 返回对列的引用(如果存在),否则返回默认值。Returns a reference to the column if it exists, otherwise - returns the default value.


column_ifexists(columnName, defaultValue)column_ifexists(columnName, defaultValue)


  • columnName:列的名称columnName: The name of the column
  • defaultValue:在使用函数的上下文中不存在列时要使用的值。defaultValue: The value to use if the column doesn't exist in the context that the function was used in. 此值可以是任何标量表达式(例如,对另一列的引用)。This value can be any scalar expression (e.g. a reference to another column).


如果“columnName”存在,则使用它引用的列。If columnName exists, then the column it refers to. 否则使用“defaultValue”。Otherwise - defaultValue.


.create function with (docstring = "Wraps a table query that allows querying the table even if columnName doesn't exist ", folder="My Functions")
ColumnOrDefault(tableName:string, columnName:string)
    // There's no column "Capital" in "StormEvents", therefore, the State column will be used instead
    table(tableName) | project column_ifexists(columnName, State)

ColumnOrDefault("StormEvents", "Capital");