एसक्यूएल सशर्त

Question

छेड़छाड़ करता है मैं जानना चाहता हूं कि हम एक अंतरंग सशर्त कर सकते हैं या नहीं। सिद्धांत कुछ सवाल है, लेकिन परिणाम गलत है (हमेशा खाली)। मैं लिखता हूं कि इसका क्या परिणाम होना चाहिए।

DECLARE @CAN_USE_TABLE1 BIT 
DECLARE @CAN_USE_TABLE2 BIT 
DECLARE @CAN_USE_TABLE3 BIT 
DECLARE @CAN_USE_TABLE4 BIT 

DECLARE @TABLE1 AS TABLE (ABC INT) -- values will be 1,2,3 
DECLARE @TABLE2 AS TABLE (ABC INT) -- values will be 1,2 
DECLARE @TABLE3 AS TABLE (ABC INT) --EMPTY TABLE 
DECLARE @TABLE4 AS TABLE (ABC INT) --EMPTY TABLE 
INSERT INTO @TABLE1 VALUES (1) 
INSERT INTO @TABLE1 VALUES (2) 
INSERT INTO @TABLE1 VALUES (3) 
INSERT INTO @TABLE2 VALUES (1) 
INSERT INTO @TABLE2 VALUES (2) 

SET @CAN_USE_TABLE1 = 1 
SET @CAN_USE_TABLE2 = 1 
SET @CAN_USE_TABLE3 = 1 
SET @CAN_USE_TABLE4 = 0 

SELECT ABC FROM @TABLE1 WHERE @CAN_USE_TABLE1 = 1 
INTERSECT 
SELECT ABC FROM @TABLE2 WHERE @CAN_USE_TABLE2 = 1 
INTERSECT 
SELECT ABC FROM @TABLE3 WHERE @CAN_USE_TABLE3 = 1 
INTERSECT 
SELECT ABC FROM @TABLE4 WHERE @CAN_USE_TABLE4 = 1 

--RESULT SHOULD BE : 
-- NO RESULT 
-- 
-- BECAUSE, AT THIS STAGE, TABLE1 AND TABLE2 AND TABLE3 SHOULD BE INTERSECTED. AND BECAUSE TABLE3 IS EMPTY, THE RESULT IS EMPTY. 

SET @CAN_USE_TABLE1 = 1 
SET @CAN_USE_TABLE2 = 1 
SET @CAN_USE_TABLE3 = 0 
SET @CAN_USE_TABLE4 = 0 

SELECT ABC FROM @TABLE1 WHERE @CAN_USE_TABLE1 = 1 
INTERSECT 
SELECT ABC FROM @TABLE2 WHERE @CAN_USE_TABLE2 = 1 
INTERSECT 
SELECT ABC FROM @TABLE3 WHERE @CAN_USE_TABLE3 = 1 
INTERSECT 
SELECT ABC FROM @TABLE4 WHERE @CAN_USE_TABLE4 = 1 

--RESULT SHOULD BE : 
-- 1 
-- 2 
-- 
-- BECAUSE, AT THIS STAGE, TABLE1 AND TABLE2 SHOULD BE INTERSECTED 

SET @CAN_USE_TABLE1 = 0 
SET @CAN_USE_TABLE2 = 1 
SET @CAN_USE_TABLE3 = 0 
SET @CAN_USE_TABLE4 = 0 

SELECT ABC FROM @TABLE1 WHERE @CAN_USE_TABLE1 = 1 
INTERSECT 
SELECT ABC FROM @TABLE2 WHERE @CAN_USE_TABLE2 = 1 
INTERSECT 
SELECT ABC FROM @TABLE3 WHERE @CAN_USE_TABLE3 = 1 
INTERSECT 
SELECT ABC FROM @TABLE4 WHERE @CAN_USE_TABLE4 = 1 

--RESULT SHOULD BE : 
-- 1 
-- 2 
-- 
-- BECAUSE, AT THIS STAGE, ONLY TABLE 2 SHOULD BE USED 

Answer 1

किसी अन्य सेट के साथ एक खाली सेट INTERSECT एड हमेशा खाली हो जाएगा। यह 0. से गुणा तुम हमेशा मिल की तरह है 0.

सशर्त INTERSECT आईएनजी या तो एक गतिशील क्वेरी, या एक मचान मेज, इस तरह की आवश्यकता होगी:

initializations

DECLARE @CAN_USE_TABLE1 BIT 
DECLARE @CAN_USE_TABLE2 BIT 
DECLARE @CAN_USE_TABLE3 BIT 
DECLARE @CAN_USE_TABLE4 BIT 

DECLARE @TABLE1 AS TABLE (ABC INT) 
DECLARE @TABLE2 AS TABLE (ABC INT) 
DECLARE @TABLE3 AS TABLE (ABC INT) 
DECLARE @TABLE4 AS TABLE (ABC INT) 
DECLARE @RESULT AS TABLE (ABC INT) --Adding this result table 
INSERT INTO @TABLE1 VALUES (1) 
INSERT INTO @TABLE1 VALUES (2) 
INSERT INTO @TABLE1 VALUES (3) 
INSERT INTO @TABLE2 VALUES (1) 
INSERT INTO @TABLE2 VALUES (2) 

SET @CAN_USE_TABLE1 = 1 
SET @CAN_USE_TABLE2 = 1 
SET @CAN_USE_TABLE3 = 0 
SET @CAN_USE_TABLE4 = 0 

प्रसंस्करण

INSERT INTO @RESULT 
SELECT ABC FROM @TABLE1 WHERE @CAN_USE_TABLE1=1 UNION 
SELECT ABC FROM @TABLE2 WHERE @CAN_USE_TABLE2=1 UNION 
SELECT ABC FROM @TABLE3 WHERE @CAN_USE_TABLE3=1 UNION 
SELECT ABC FROM @TABLE4 WHERE @CAN_USE_TABLE4=1 

DELETE r FROM @RESULT r 
WHERE NOT EXISTS(SELECT 1 FROM @TABLE1 WHERE ABC=r.ABC) 
AND @CAN_USE_TABLE1=1; 

DELETE r FROM @RESULT r 
WHERE NOT EXISTS(SELECT 1 FROM @TABLE2 WHERE ABC=r.ABC) 
AND @CAN_USE_TABLE2=1; 

DELETE r FROM @RESULT r 
WHERE NOT EXISTS(SELECT 1 FROM @TABLE3 WHERE ABC=r.ABC) 
AND @CAN_USE_TABLE3=1; 

DELETE r FROM @RESULT r 
WHERE NOT EXISTS(SELECT 1 FROM @TABLE4 WHERE ABC=r.ABC) 
AND @CAN_USE_TABLE4=1; 

SELECT * FROM @RESULT; 

परिणाम

1 
2 

Answer 2

declare @sql nvarchar(4000), 
    @params nvarchar(4000) 

if @can_use_table1 = 1 
    select @sql= 'select abc from @table1' 

if @can_use_table2 = 1 
begin 
    if @can_use_table1 = 1 
     select @sql = @sql + ' intersect ' 
    select @sql = @sql + 'select abc from @table2' 
end 

if @can_use_table3 = 1 
begin 
    if @can_use_table1 = 1 or @can_use_table2 = 1 
     select @sql= @sql + ' intersect '   
    select @sql= @sql + 'select abc from @table3' 
end 

if @can_use_table4 = 1 
begin 
    if @can_use_table1 = 1 or @can_use_table2 = 1 or @can_use_table3 = 1 
     select @sql= @sql + ' intersect ' 
    select @sql= @sql + 'select abc from @table4'  
end 

select @params ='@can_use_table1 bit, @can_use_table2 bit, 
     @can_use_table3 bit, @can_use_table4 bit, 
@table1 table, @table2 table, @table3 table, @table4 table' 

exec sp_executesql @sql,@params, 
     @can_use_table1,@can_use_table2, @can_use_table3, @can_use_table4, 
     @table1, @table2, @table3, @table4 

Answer 3

आप के रूप में किसी एक क्वेरी में ऐसा कर सकता है:

select ABC 
from (SELECT ABC, @CAN_USE_TABLE1 as CanUse1, 0 as CanUse2, 0 as CanUse3, 0 as CanUse4 
     FROM @TABLE1 
     union all 
     SELECT ABC, 0, @CAN_USE_TABLE2, 0, 0 FROM @TABLE2 
     union all 
     SELECT ABC, 0, 0, @CAN_USE_TABLE3, 0 FROM @TABLE3 
     union all 
     SELECT ABC, 0, 0, 0, @CAN_USE_TABLE4 FROM @TABLE4 
    ) t 
group by ABC 
having max(Canuse1) = @CAN_USE_TABLE1 AND 
     max(CanUse2) = @CAN_USE_TABLE2 AND 
     max(CanUse3) = @CAN_USE_TABLE3 And 
     max(CanUse4) = @CAN_USE_TABLE4