NVL(B.WT1,C.WT1)在sql里什么意思

在 SQL 中，NVL 函数用于将一个空值或 NULL 值替换为另一个值。它的语法通常是：NVL(expression1, expression2)。如果 expression1 不是 NULL，则 NVL 返回 expression1 的值，否则返回 expression2 的值。

在你提供的例子中，NVL(B.WT1, C.WT1) 表示如果 B.WT1 不是 NULL，则返回 B.WT1 的值，否则返回 C.WT1 的值。这通常在 SQL 查询中用于处理 NULL 值，以使查询结果更加完整和准确。

相关问题

优化这个sql SELECT count( 1 ) FROM ( SELECT B.ID, B.PURCHASE_REQUEST_ID, B.MATERIAL_ID, B.MATERIAL_CODE, B.MATERIAL_NAME, B.STANDARD, B.MODEL_ID, B.BILL_ROW_ID, B.BILL_NO, BILL_NAME, B.MODEL_CODE, B.MODEL_NAME, B.PARENT_MODEL_ID, B.PARENT_MODEL_CODE, B.PARENT_MODEL_NAME, B.UNIT_CODE, B.UNIT_NAME, B.PURCHASE_TYPE_CODE, CAST( NVL( B.APPLY_NUM, 0 ) AS NUMBER ( 24, 10 ) ) AS APPLY_NUM, CAST( NVL( B.DEAL_NUM, 0 ) AS NUMBER ( 24, 10 ) ) AS DEAL_NUM, CAST( NVL( B.RETURN_NUM, 0 ) AS NUMBER ( 24, 10 ) ) AS RETURN_NUM, B.DEAL_USER_ID, B.DEAL_USER_NAME, CAST( NVL( B.PRICE, 0 ) AS NUMBER ( 24, 10 ) ) AS PRICE, CAST( NVL( B.AMOUNT, 0 ) AS NUMBER ( 24, 10 ) ) AMOUNT, B.IMPLEMENT_CODE, B.IMPLEMENT_NAME, B.IMPLEMENT_INVEST_AMOUNT, B.PURCHASE_MANAGER_ID, B.PURCHASE_MANAGER_NAME, B.PROVIDER_ID, B.PROVIDER_NAME, B.REMARK, B.DELIVER_AREA, B.DELIVER_ADDRESS, B.RECEIVE_PEOPLE, B.RECEIVE_PEOPLE_PHONE, B.ITEM_STATUS, B.COST_CENTER, B.COST_BUDGET_CODE, B.COST_IMPLEMENT_NAME, B.FRAME_CONT_ID, B.FRAME_CONT_CODE, B.FRAME_CONT_NAME, B.DETAIL_CONFIG, B.PURCHASE_CATEGORY_CODE, B.INVOICE_TITLE_CODE, B.INVOICE_SEND_ADDRRSS, B.MATERIAL_REQUEST_ITEM_ID, B.YEAR, B.DELETE_FLAG, B.PROVINCE_CODE, B.REASON, B.PARENT_ITEM_ID, B.FRAME_CONT_ITEM_ID, B.SUB_MATERIAL_REQUEST_ID, B.SUB_MATERIAL_REQUEST_CODE, B.MATERIAL_URL, B.RECOMMEND_PROVIDER_NAMES, C.PURCHASE_REQUEST_CODE, C.PURCHASE_REQUEST_NAME, C.APPLY_TYPE_CODE, C.CREATOR_NAME, C.APPLY_TELEPHONE, C.COMPANY_NAME, C.DEPT_NAME, B.CREATE_TIME, TO_CHAR( B.CREATE_TIME, 'YYYY-MM-DD' ) CREATE_TIME_STR, C.ARRIVE_TIME, C.IS_TO_END, C.MONEY_WAY_CODE, C.OWN, C.APPLY_CATEGORY_CODE, C.manu_Type, C.BILL_ID, MMD.MATERIAL_TYPE_CODE, B.BRANCH_COMPANY_DEAL_USER_ID, B.BRANCH_COMPANY_DEAL_USER_NAME, ( SELECT ORG_NAME FROM ORGANIZATIONS WHERE DELETE_FLAG = '0' AND ORG_CODE = ( SELECT PARENT_COMPANY_NO FROM ORGANIZATIONS WHERE ID = B.MATERIAL_DEPT_ID )) AS MATERIAL_COMPANY_NAME, B.ORIGINAL, B.PROVIDER_PRODUCT_MODEL, B.PROVIDER_PRODUCT_NAME, B.PRODUCT_DESC, B.Back_Flag, CASE WHEN MMD.material_type_code = 'WZ' THEN '1' WHEN MMD.material_type_code = 'FW' THEN '2' ELSE '3' END apply_category_code_item, NVL( C.IS_CARDSYSTEM_REQUEST, '0' ) IS_CARDSYSTEM_REQUEST, B.APPLY_GROUP_AUTHORITES, B.SCIENTIFIC_RESEARCH_ID, B.SCIENTIFIC_RESEARCH_CODE, B.SCIENTIFIC_RESEARCH_NAME, B.PREQUALFY_CODE, nvl( C.IS_QUICK, '0' ) AS IS_QUICK, C.PURCHASE_WAY_CODE, C.PURCHASE_TYPE_CODE PURCHASE_TYPE_CODE_P, C.ORIGINAL_TYPE, C.PURCHASE_REQUEST_BILLS_TYPE, B.IS_FRAME_CONT_MONAD FROM PURCHASE_REQUEST_ITEM B LEFT JOIN PURCHASE_REQUEST C ON B.PURCHASE_REQUEST_ID = C.ID LEFT JOIN MATERIAL_DATA MMD ON MMD.ID = B.MATERIAL_ID AND MMD.DELETE_FLAG = '0' WHERE B.delete_flag = '0' AND B.Item_Status IN ( 1 ) AND NOT EXISTS ( SELECT * FROM purchase_request_item_log pril WHERE B.id = pril.purchase_request_item_id AND pril.lock_status = '1' AND pril.delete_flag = '0' ) AND ( ( c.apply_type_code NOT IN ( '20', '41', '3' ) AND nvl( B.Apply_Num, 0 ) > nvl( B.Deal_Num, 0 )) OR c.apply_type_code IN ( '20', '41', '3' ) ) AND B.Deal_User_Id =: 1 AND C.MONEY_WAY_CODE =: 2 AND C.APPLY_TYPE_CODE =: 3 AND C.PAY_OUT_TYPE_CODE =: 4 AND C.APPLY_CATEGORY_CODE =: 5 AND NVL( C.IS_CARDSYSTEM_REQUEST, '0' ) = : 6 AND NOT EXISTS ( SELECT * FROM purchase_request_item p left join material_province mp ON p.material_id = mp.material_id WHERE p.delete_flag = 0 AND mp.delete_flag = 0 AND mp.material_status = 03 AND mp.org_code = p.province_code AND p.id = B.id ) ORDER BY C.ID, B.ID ASC)

首先，可以将子查询中的所有列名改为别名，这样可以避免重名和提高代码可读性。另外，可以尝试使用 EXISTS 子查询来替换 NOT EXISTS 子查询，因为 EXISTS 子查询的性能通常更好。最后，可以考虑对 WHERE 子句中的多个条件进行逻辑上的分组，以避免出现过于复杂的条件表达式。下面是优化后的 SQL：

SELECT COUNT(1)
FROM (
SELECT
b.ID,
b.PURCHASE_REQUEST_ID,
b.MATERIAL_ID,
b.MATERIAL_CODE,
b.MATERIAL_NAME,
b.STANDARD,
b.MODEL_ID,
b.BILL_ROW_ID,
b.BILL_NO,
b.BILL_NAME,
b.MODEL_CODE,
b.MODEL_NAME,
b.PARENT_MODEL_ID,
b.PARENT_MODEL_CODE,
b.PARENT_MODEL_NAME,
b.UNIT_CODE,
b.UNIT_NAME,
b.PURCHASE_TYPE_CODE,
CAST(NVL(b.APPLY_NUM, 0) AS NUMBER(24, 10)) AS APPLY_NUM,
CAST(NVL(b.DEAL_NUM, 0) AS NUMBER(24, 10)) AS DEAL_NUM,
CAST(NVL(b.RETURN_NUM, 0) AS NUMBER(24, 10)) AS RETURN_NUM,
b.DEAL_USER_ID,
b.DEAL_USER_NAME,
CAST(NVL(b.PRICE, 0) AS NUMBER(24, 10)) AS PRICE,
CAST(NVL(b.AMOUNT, 0) AS NUMBER(24, 10)) AMOUNT,
b.IMPLEMENT_CODE,
b.IMPLEMENT_NAME,
b.IMPLEMENT_INVEST_AMOUNT,
b.PURCHASE_MANAGER_ID,
b.PURCHASE_MANAGER_NAME,
b.PROVIDER_ID,
b.PROVIDER_NAME,
b.REMARK,
b.DELIVER_AREA,
b.DELIVER_ADDRESS,
b.RECEIVE_PEOPLE,
b.RECEIVE_PEOPLE_PHONE,
b.ITEM_STATUS,
b.COST_CENTER,
b.COST_BUDGET_CODE,
b.COST_IMPLEMENT_NAME,
b.FRAME_CONT_ID,
b.FRAME_CONT_CODE,
b.FRAME_CONT_NAME,
b.DETAIL_CONFIG,
b.PURCHASE_CATEGORY_CODE,
b.INVOICE_TITLE_CODE,
b.INVOICE_SEND_ADDRRSS,
b.MATERIAL_REQUEST_ITEM_ID,
b.YEAR,
b.DELETE_FLAG,
b.PROVINCE_CODE,
b.REASON,
b.PARENT_ITEM_ID,
b.FRAME_CONT_ITEM_ID,
b.SUB_MATERIAL_REQUEST_ID,
b.SUB_MATERIAL_REQUEST_CODE,
b.MATERIAL_URL,
b.RECOMMEND_PROVIDER_NAMES,
c.PURCHASE_REQUEST_CODE,
c.PURCHASE_REQUEST_NAME,
c.APPLY_TYPE_CODE,
c.CREATOR_NAME,
c.APPLY_TELEPHONE,
c.COMPANY_NAME,
c.DEPT_NAME,
b.CREATE_TIME,
TO_CHAR(b.CREATE_TIME, 'YYYY-MM-DD') CREATE_TIME_STR,
c.ARRIVE_TIME,
c.IS_TO_END,
c.MONEY_WAY_CODE,
c.OWN,
c.APPLY_CATEGORY_CODE,
c.manu_Type,
c.BILL_ID,
MMD.MATERIAL_TYPE_CODE,
b.BRANCH_COMPANY_DEAL_USER_ID,
b.BRANCH_COMPANY_DEAL_USER_NAME,
(SELECT ORG_NAME FROM ORGANIZATIONS WHERE DELETE_FLAG = '0' AND ORG_CODE = (SELECT PARENT_COMPANY_NO FROM ORGANIZATIONS WHERE ID = b.MATERIAL_DEPT_ID)) AS MATERIAL_COMPANY_NAME,
b.ORIGINAL,
b.PROVIDER_PRODUCT_MODEL,
b.PROVIDER_PRODUCT_NAME,
b.PRODUCT_DESC,
b.Back_Flag,
CASE
WHEN MMD.material_type_code = 'WZ' THEN '1'
WHEN MMD.material_type_code = 'FW' THEN '2'
ELSE '3'
END apply_category_code_item,
NVL(c.IS_CARDSYSTEM_REQUEST, '0') IS_CARDSYSTEM_REQUEST,
b.APPLY_GROUP_AUTHORITES,
b.SCIENTIFIC_RESEARCH_ID,
b.SCIENTIFIC_RESEARCH_CODE,
b.SCIENTIFIC_RESEARCH_NAME,
b.PREQUALFY_CODE,
NVL(c.IS_QUICK, '0') AS IS_QUICK,
c.PURCHASE_WAY_CODE,
c.PURCHASE_TYPE_CODE PURCHASE_TYPE_CODE_P,
c.ORIGINAL_TYPE,
c.PURCHASE_REQUEST_BILLS_TYPE,
b.IS_FRAME_CONT_MONAD
FROM PURCHASE_REQUEST_ITEM b
LEFT JOIN PURCHASE_REQUEST c ON b.PURCHASE_REQUEST_ID = c.ID
LEFT JOIN MATERIAL_DATA MMD ON MMD.ID = b.MATERIAL_ID AND MMD.DELETE_FLAG = '0'
WHERE b.delete_flag = '0'
AND b.Item_Status IN (1)
AND b.Deal_User_Id = :1
AND C.MONEY_WAY_CODE = :2
AND C.APPLY_TYPE_CODE = :3
AND C.PAY_OUT_TYPE_CODE = :4
AND C.APPLY_CATEGORY_CODE = :5
AND NVL(C.IS_CARDSYSTEM_REQUEST, '0') = :6
AND EXISTS (
SELECT *
FROM purchase_request_item_log pril
WHERE B.id = pril.purchase_request_item_id
AND pril.lock_status = '1'
AND pril.delete_flag = '0'
)
AND (
c.apply_type_code IN ('20', '41', '3')
OR (
c.apply_type_code NOT IN ('20', '41', '3')
AND NVL(b.Apply_Num, 0) > NVL(b.Deal_Num, 0)
)
)
AND NOT EXISTS (
SELECT *
FROM purchase_request_item p
LEFT JOIN material_province mp ON p.material_id = mp.material_id
WHERE p.delete_flag = 0
AND mp.delete_flag = 0
AND mp.material_status = 03
AND mp.org_code = p.province_code
AND p.id = b.id
)
ORDER BY c.ID, b.ID ASC
)

理解这段逻辑BEGIN o_code := 1; o_note := '查询成功'; IF i_pd_cd IS NULL THEN o_code := -501; o_note := '错误：产品不可为空!'; RETURN; END IF; OPEN o_cursor FOR SELECT a.pd_name, a.pd_abbr, a.pd_cd, to_char(to_date(sale_strt_date, 'yyyy-mm-dd'), 'yyyy-mm-dd') scrp_strt_date, to_char(to_date(sale_end_date, 'yyyy-mm-dd'), 'yyyy-mm-dd') scrp_end_date, b.sale_scal, 0 lim_ivst_num, c.mino_lmt_agmt_vol, 0 ntrl_prsn_lim_num, nvl(b.indv_scrp_orgn, 0) indv_scrp_orgn, nvl(b.indv_scrp_base, 0) indv_scrp_base, nvl(b.ins_scrp_orgn, 0) ins_scrp_orgn, nvl(b.ins_scrp_base, 0) ins_scrp_base, nvl(b.indv_purs_orgn, 0) indv_purs_orgn, nvl(b.indv_purs_base, 0) indv_purs_base, nvl(b.ins_purs_orgn, 0) ins_purs_orgn, nvl(b.ins_purs_base, 0) ins_purs_base FROM product.tpd_trus a LEFT JOIN product.tpd_trd_para b ON a.pd_cd = b.pd_cd LEFT JOIN crm.tmkt_pd_lmt_assn_mag c ON a.pd_cd = c.pd_cd WHERE b.pd_cd = i_pd_cd;

这段代码是一个存储过程的逻辑。它的功能是根据给定的产品代码（i_pd_cd），查询相关的产品信息并将结果返回。

首先，它将输出参数 o_code 设置为1，表示查询成功，将 o_note 设置为"查询成功"。

然后，它检查输入参数 i_pd_cd 是否为空。如果为空，将 o_code 设置为-501，表示错误，将 o_note 设置为"错误：产品不可为空!"，并终止执行。

如果 i_pd_cd 不为空，则使用一个游标（o_cursor）来执行查询操作。查询语句从 product.tpd_trus 表中选择相关列，并左连接 product.tpd_trd_para 表和 crm.tmkt_pd_lmt_assn_mag 表。其中，使用 pd_cd 进行表之间的关联。

最后，将查询的结果集赋值给 o_cursor 游标，并返回给调用者。

请注意，这只是代码的一部分，可能还有其他部分未包含在内。如果您需要更多的帮助或有其他问题，请随时提问。