Question

仅当计数为1时计数器才会计数，随后的加法则不会计数

if exists (select 1 from login_counter where emailaddress = @useremail)
    update login_counter 
    set counts = counts+1, - here i want to add a check if the count is 1, add the lasttry which is justbelow to the date but every new count, don't update that 
        lasttry = GETDATE() 
    where emailaddress = @useremail;
else
    insert into login_counter (counts, emailaddress, lasttry) 
    values (1, @useremail, GETDATE());

我这样尝试过：

仅当计数为1时计数器才会计数，随后的加法则不会计数

if exists (select 1 from login_counter where emailaddress = @useremail)
    update login_counter 
    set counts = counts + 1,
        lasttry = CASE WHEN (select lasttry from login_counter where emailaddress = @useremail) = NULL THEN GetDate() 
    where emailaddress = @useremail;
else
    insert into login_counter (counts,emailaddress,lasttry) 
    values (1, @useremail, GETDATE());

我收到此错误：

第156条消息，级别15，状态1，第5行
关键字“ where”附近的语法不正确

Answer 1

我不明白您要做什么，但是由于以下行，您遇到语法错误：

lasttry = CASE WHEN (select lasttry from login_counter where emailaddress = @useremail) = NULL THEN GetDate()

缺少END表达式的CASE。

Answer 2

我认为您可能可以像这样重写案例声明：

lasttry = CASE WHEN NOT EXISTS (select lasttry from login_counter where emailaddress = @useremail) THEN GetDate() END

否则，您将要确保CASE中的子查询仅返回单个值，例如SELECT TOP 1 lasttry ...或SELECT MAX(lasttry) ...。如果子查询返回多个值，则比较表达式将炸弹。

仅在第一次计数时更新

2 个答案: