如何从SQL（T-SQL）中的日期组件创建日期？

为什么将输入数据作为字符串，最明显（因此不足为奇，对不起）的解决方案之一是：

SELECt  mydate = CAST([year] + RIGHt('0' + [month], 2) + '01' AS datetime)          FROM (  SELECT [month] = '2',  [year] = '2011' UNIOn ALL  SELECT [month] = '03', [year] = '2011' UNIOn ALL  SELECT [month] = '5',  [year] = '2011' UNIOn ALL  SELECT [month] = '12', [year] = '2011' UNIOn ALL  SELECT [month] = '8',  [year] = '2084' UNIOn ALL  SELECT [month] = '1',  [year] = '1940') x;