CARDINALITY 函数返回列表中元素的数量。
CARDINALITY 返回一个整数值,表明 ListExpression 指定的列表中的元素数量。
此函数通常用于在迭代前确定列表中的字段数量。
-- Determine the number of F1 fields in the message. -- Note that the [ ] are required DECLARE CountF1 INT CARDINALITY(OutputRoot.XML.Data.Source.F1[]);
-- Determine the number of fields called F1 with the value 'F12' in the message. -- Again note that the [ ] are required DECLARE CountF1F12 INT CARDINALITY(SELECT F.* FROM OutputRoot.XML.Data.Source.F1[] AS F where F = 'F12');
-- Use the value returned by CARDINALITY to refer to a specific element -- in a list or array: -- Array indices start at 1, so this example refers to the third-from-last -- instance of the Item field Body.Invoice.Item[CARDINALITY(Body.Invoice.Item[]) - 2].Quantity