Question

我一直在尝试执行if和else语句。但是，每次执行都表示错误，例如功能错误或语法相关错误。

CREATE trigger [dbo].[TRIAL]
on [dbo].[TBL1]

after INSERT 
AS 
BEGIN
    SET NOCOUNT ON;

    IF TBL1.NUMBER = TBL2.NUMBER  THEN    
      insert into TBL3 (NAME,HEIGHT)    
      select NAME,HEIGHT    
      from TBL1,TBL2  

   ELSE     
      PRINT 'WRONG NUMBER'

end

请您能帮助我纠正这个问题吗？

Answer 1

要扩展Alex K的评论：

declare @Flag bit = 1;

-- ERROR: There is no THEN keyword.
if @Flag = 1 then
    select 'A';

-- CORRECT: Omit THEN and this works as expected.
if @Flag = 1
    select 'A';


-- ERROR: Only the first SELECT is associated with the IF, so the ELSE is unmatched.
if @Flag = 2
    select 'B1';
    select 'B2';
else
    select 'C';

-- CORRECT: If each branch of the IF has only one statement, then this construction is okay.
if @Flag = 2
    select 'B1';
else
    select 'C';

-- CORRECT: If you want multiple statements in either branch of the IF, make them into a block using BEGIN/END.
if @Flag = 2
begin
    select 'B1';
    select 'B2';
end
else
    select 'C';

-- CORRECT: You can also use BEGIN/END with single statements if you like. 
if @Flag = 2
begin
    select 'B1';
    select 'B2';
end
else
begin
    select 'C';
end

SQL IF和ELSE语句

1 个答案: