需要幫助刪除嵌套的內部連接

Question

我在SQL查詢中有以下INNER JOIN語句，我想更改，因此沒有嵌套的INNER JOIN語句。我相信這會導致笛卡爾積，因爲它需要20多分鐘才能返回幾千行結果。有人可以幫我弄清楚如何去除嵌套？

SELECT   
TECH_INCDT_V.INCDT_NUM_I AS [Incident Number], 
TECH_INCDT_V.ASGN_TO_USER_I AS [Incident Assigned User ID], 
SVY_RESP_V_3.RESP_VAL_Q AS [Survey Response], 
SVY_QUES_V_3.QUES_T AS [Survey Question] 


FROM supt_oper_anls_dw.dbo.SVY_QUES_V AS SVY_QUES_V_7 
INNER JOIN supt_oper_anls_dw.dbo.SVY_RESP_V AS SVY_RESP_V_7 ON SVY_QUES_V_7.SVY_QUES_I = SVY_RESP_V_7.SVY_QUES_I 

-->START INNER JOIN "A" 
INNER JOIN supt_oper_anls_dw.dbo.TECH_INCDT_V 

    -->These are NESTED within the INNER JOIN "A" in the previous line 
    INNER JOIN supt_oper_anls_dw.dbo.PERS_V ON TECH_INCDT_V.CRTE_USER_I = PERS_V.PERS_LAN_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_TASK_V ON TECH_INCDT_V.INCDT_NUM_I = SVY_TASK_V.INCDT_NUM_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_INSTC_V ON SVY_TASK_V.SVY_INSTC_I = SVY_INSTC_V.SVY_INSTC_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_RESP_V ON SVY_INSTC_V.SVY_INSTC_I = SVY_RESP_V.SVY_INSTC_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_QUES_V ON SVY_RESP_V.SVY_QUES_I = SVY_QUES_V.SVY_QUES_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_TASK_V AS SVY_TASK_V_3 ON TECH_INCDT_V.INCDT_NUM_I = SVY_TASK_V_3.INCDT_NUM_I AND SVY_INSTC_V.SVY_INSTC_I = SVY_TASK_V_3.SVY_INSTC_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_RESP_V AS SVY_RESP_V_3 ON SVY_INSTC_V.SVY_INSTC_I = SVY_RESP_V_3.SVY_INSTC_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_QUES_V AS SVY_QUES_V_3 ON SVY_RESP_V_3.SVY_QUES_I = SVY_QUES_V_3.SVY_QUES_I 
    INNER JOIN supt_oper_anls_dw.dbo.SVY_TASK_V AS SVY_TASK_V_7 ON TECH_INCDT_V.INCDT_NUM_I = SVY_TASK_V_7.INCDT_NUM_I AND SVY_INSTC_V.SVY_INSTC_I = SVY_TASK_V_7.SVY_INSTC_I 
    -->Nesting ends here 

-->END INNER JOIN "A" 
ON SVY_RESP_V_7.SVY_INSTC_I = SVY_INSTC_V.SVY_INSTC_I 

INNER JOIN supt_oper_anls_dw.dbo.PERS_V AS PERS_V_2 ON SVY_INSTC_V.CMPL_BY_USER_I = PERS_V_2.PERS_LAN_I 
LEFT OUTER JOIN supt_oper_anls_dw.dbo.ACCT_DATE_DIM AS ACCT_DATE_DIM_OPEN ON CONVERT(varchar(8), TECH_INCDT_V.CRTE_TS, 112) = ACCT_DATE_DIM_OPEN.GREG_D 
LEFT OUTER JOIN supt_oper_anls_dw.dbo.ACCT_DATE_DIM AS ACCT_DATE_DIM_SVY ON CONVERT(varchar(8), SVY_INSTC_V.CMPL_TS, 112) = ACCT_DATE_DIM_SVY.GREG_D 

WHERE   
(SVY_QUES_V.SVY_QUES_I IS NOT NULL) AND 
(TECH_INCDT_V.CRTE_WKGRP_N LIKE '%FAKE%' OR TECH_INCDT_V.CRTE_WKGRP_N IS NULL) 

GROUP BY 
TECH_INCDT_V.INCDT_NUM_I, 
TECH_INCDT_V.ASGN_TO_USER_I, 
SVY_RESP_V_3.RESP_VAL_Q, 
SVY_QUES_V_3.QUES_T, 
SVY_QUES_V_3.SVY_QUES_I, 
TECH_INCDT_V.CRTE_TS 

我試圖擺脫嵌套的INNER JOIN這裏之間的語句：

INNER JOIN supt_oper_anls_dw.dbo.TECH_INCDT_V 

這裏：

ON SVY_RESP_V_7.SVY_INSTC_I = SVY_INSTC_V.SVY_INSTC_I 

Answer 1

沒有 '套' joins（無論這可能意味着什麼），只是不完整joins。您的inner join'A'沒有ON條款。您在評論中提到的ON子句與連接中的表沒有關係。你是joining supt_oper_anls_dw.dbo.PERS_V on表中的連接'A'（以及其他幾個），但你不是joining supt_oper_anls_dw.dbo.TECH_INCDT_V到其他任何東西。正如@navigator所說，你需要在連接「A」之後和所謂的「嵌套」連接之前添加ON子句。所提供的信息不可能說什麼ON條款。

另外，你的RDBMS是什麼？