Sql intersect condizionale

Question

Desidero sapere se è possibile eseguire un condizionale intersect. c'è la query somes, ma il risultato è sbagliato (sempre vuoto). Scrivo cosa dovrebbe comportare.

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

Un insieme vuoto INTERSECT cata con qualsiasi altro insieme saranno sempre vuota. E 'come moltiplicare per 0. Si ottiene sempre 0.

condizionale INTERSECT ing richiederà una query dinamica, o di una tabella di gestione temporanea, in questo modo:

Inizializzazioni

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 

Processing

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; 

Risultato

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

Si potrebbe fare questo in una singola query come:

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