sql条件下每种情况的不同限制

Question

我想在特定条件下阻塞的情况下进行限制，有没有简单的方法；

我有一个这样的 sql ；我想限制条件 4,5,6 到 50K;

select SUBSCRIBER_KEY,
coalesce(
    case when pct_1 >90 then  
                case when <condition_1> then 'L_1' 
                     when <condition_2> then 'L_2'
                     when <condition_3> then 'L_3'
                end 
    else null end,
    case when pct_2<=90 and t.wk_dec_pct<=0.2 
                then
                case when <condition_4> then 'L_4' --to limit output of this condition 50000
                     when <condition_5> then 'L_5' --to limit output of this condition 50000
                     when <condition_6> then 'L_6' --to limit output of this condition 50000
                end
    else null end,
    case when pct_2<=90 and t.wk_dec_pct>=0.2 and t.acc_type='main' 
                then
                case when <condition_7> then 'L_7'
                     when <condition_8> then 'L_8'
                     when <condition_9> then 'L_9'
                end
    else null end                                                
)      
from table_t t
where ...

Answer 1

select SUBSCRIBER_KEY,
coalesce(
    case when pct_1 >90 then  
                case when <condition_1> then 'L_1' 
                     when <condition_2> then 'L_2'
                     when <condition_3> then 'L_3'
                end 
    else null end,
    case when pct_2<=90 and t.wk_dec_pct<=0.2 
                then
                case when RecordIndex <= 50000 then 'L_4' --to limit output of this condition 50000
                     when RecordIndex <= 100000 then 'L_5' --to limit output of this condition 50000
                     when RecordIndex <= 150000 then 'L_6' --to limit output of this condition 50000
                end
    else null end,
    case when pct_2<=90 and t.wk_dec_pct>=0.2 and t.acc_type='main' 
                then
                case when <condition_7> then 'L_7'
                     when <condition_8> then 'L_8'
                     when <condition_9> then 'L_9'
                end
    else null end                                                
)      
from 
(SELECT
    SUBSCRIBER_KEY,
    pct_1,
    pct_2,
    wk_dec_pct,
    acc_type,
    ROW_NUMBER() OVER (ORDER BY MyOrderColumnForConsistency) RecordIndex
FROM    
    table_t) t
where ...

或者，您可以使用类似以下的方法计算 L_ 值：

case when pct_2<=90 and t.wk_dec_pct<=0.2 
                    then
                    'L_' + CAST((RecordIndex / 50000) + 4 as varchar(2))                    
                    end
        else null end,

我不禁认为这个查询应该以更好的方式构造。