等号(=)和IN与子查询之间的差异

Question

我有一个查询需要20秒执行,请按照我的查询:

SELECT MATLIGA.COD_MAT_FAMILIA 
FROM 
    ORCAMENTOS.dbo.OR_1INSUMOS INSUMOS
    INNER JOIN ORCAMENTOS.dbo.OR_MAT_GRUPOS GRUPOS ON (GRUPOS.EMPRESA='01' AND GRUPOS.FILIAL='01' AND GRUPOS.CODIGO_INTERNO = 'HOT' )
    INNER JOIN ORCAMENTOS.dbo.OR_MATERIAIS MATER ON (MATER.EMPRESA='01' AND MATER.FILIAL='01' AND MATER.CODIGO_GRUPO=GRUPOS.ID AND MATER.ID = INSUMOS.COD_INSUMO_MATER )
    INNER JOIN ORCAMENTOS.dbo.OR_MAT_LIGACAO MATLIGA ON (MATLIGA.EMPRESA='01' AND MATLIGA.FILIAL='01' AND MATLIGA.CODIGO_MATERIAL  = INSUMOS.COD_INSUMO_MATER)
WHERE INSUMOS.EMPRESA='01' AND INSUMOS.FILIAL='01' 
AND INSUMOS.COD_INSUMO_MATER IS NOT NULL 
AND INSUMOS.NUMERO=10865812 
AND INSUMOS.OPCAO_SIMULACAO=1 
AND INSUMOS.CODIGO_MAQUINA = (SELECT COD_MAQ_PROPOSTA FROM ORCAMENTOS.dbo.OR_1SIMULACOES AS ORC WHERE  ORC.NUMERO=10865812 AND ORC.OPCAO_SIMULACAO = 1 AND ORC.EMPRESA='01' AND ORC.FILIAL='01' )  
AND INSUMOS.OPCAO_MAQUINA = (SELECT OPCAO_MAQUINA FROM ORCAMENTOS.dbo.OR_1SIMULACOES AS ORC WHERE  ORC.NUMERO=10865812 AND ORC.OPCAO_SIMULACAO = 1  AND ORC.EMPRESA='01' AND ORC.FILIAL='01' )  
GROUP BY MATLIGA.COD_MAT_FAMILIA  
ORDER BY  1 

在这两行中,如果我将相等的信号改为(IN),(= ALL)或(= ANY),则将成本降低到1秒.

AND INSUMOS.CODIGO_MAQUINA IN (SELECT COD_MAQ_PROPOSTA FROM ORCAMENTOS.dbo.OR_1SIMULACOES AS ORC WHERE  ORC.NUMERO=10865812 AND ORC.OPCAO_SIMULACAO = 1 AND ORC.EMPRESA='01' AND ORC.FILIAL='01' )  
AND INSUMOS.OPCAO_MAQUINA IN (SELECT OPCAO_MAQUINA FROM ORCAMENTOS.dbo.OR_1SIMULACOES AS ORC WHERE  ORC.NUMERO=10865812 AND ORC.OPCAO_SIMULACAO = 1  AND ORC.EMPRESA='01' AND ORC.FILIAL='01' )  

他们之间的区别是什么？

韩国社交协会.

Answer 1

有一个小的语义差异.如果子查询匹配多个记录,则第一个查询必须失败.所以必须完成子查询直到结束:

where col1 = (select col1 from table2)

第二个查询遇到匹配后可以停止:

where col1 in (select col1 from table2)