1、CASE語句
CASE
WHEN <A> THEN <somethingA> 
WHEN <B> THEN <somethingB> 
ELSE <somethingE> 
END 
舉例：
SELECT 
     Title, 
    'Price Range' = 
    CASE 
        WHEN price IS NULL THEN 'Unpriced' 
        WHEN price < 10 THEN 'Bargain' 
        WHEN price BETWEEN 10 and 20 THEN 'Average' 
        ELSE 'Gift to impress relatives' 
    END 
FROM titles

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2、while語句

WHILE Boolean_expression
    { sql_statement | statement_block }
    [ BREAK ]
    { sql_statement | statement_block }
    [ CONTINUE ]

舉例：

declare @temp table(
[id] int identity(1,1),
title varchar(100));

delete @temp;

insert into @temp(title) 
select title from tbl_news

declare @i int
declare @rows int
declare @temp_title varchar(100)

set @i = 1
select @rows=COUNT(*) from @temp


while(@i <= @rows)
begin
select @temp_title = title from @temp where [id] = @i
insert into tbl_new(title) values @temp_title

set @i = @i + 1
end
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3、相同記錄只保留一條

delete from 表名
where id in (select min(id) from 表名 group by 欄位名 having count(欄位名)>1)