mysql - SQL 将 2 个表中的值相乘并打印语句？

Question

在从 2 个不同的表计算之后sum(frequency * weight)，如果总和大于某个数字，我试图打印出一个语句（如下），但我不断收到一个错误，说total这不是一个有效的列。

任何帮助，将不胜感激。提前致谢

DECLARE @total INT

SELECT SUM(frequency * weight) AS total
  FROM WF, WW
 WHERE WF.word = WW.word

IF total > 30
BEGIN
  print 'Alert! Bullying post'
END
ELSE
BEGIN
  print'Normal Post'
END

Answer 1

declare @Total as Int;

select @Total = Sum( WF.Frequency * WW.Weight )
  from WF inner join
    WW on WW.Word = WF.Word;

print case when @Total > 30 then 'Alert! Bullying post!' else 'Normal post.' end;