SQL填充字段，包含來自同一表中另一條記錄的數據

Question

contract  rec  #     state  dealer  coverage
--------  ---  ----  -----  ------  --------
55661     1    YUFL  FL     GP      GP15  
55661     2    YUFL  FL     GP    
55662     1    YUFL  FL     GP      GP16  
55662     2    YUFL  FL     GP

REC'2'的覆蓋范圍字段為空。 如何用REC'1'用相同的合同＃填充覆蓋范圍字段中的相同數據？ 表名：contract_ex

即

55661 REC'2' coverage s/b GP15
55662 REC'2' coverage s/b GP16

Answer 1

嘗試這個：

SELECT  contract,
        rec,
        state,
        dealer,
        (SELECT coverage FROM YourTable
         WHERE contract = T.contract AND rec = 1) coverage
FROM YourTable T