Question

我有2张这样的桌子：

CREATE TABLE t1
(
    [SupplyTitle] [NVARCHAR](50) NOT NULL,
    [EmployeeCode] INT NOT NULL,
    [registered] DATETIME,
    [modified]  DATETIME
) 

CREATE TABLE t2
(
    [SupplyTitle] [NVARCHAR](50) NOT NULL,
    [EmployeeCode] INT NOT NULL,
    [AnnouncementID] INT NOT NULL
    [registered] DATETIME,
    [modified]  DATETIME
)

t1中的记录如下：

SupplyTitle  EmployeeCode  registered                 modified
-----------------------------------------------------------------------------
aaa          9001         2018-11-15 15:41:36.613     2018-11-15 15:41:36.613
bbb          9002         2018-11-15 15:42:36.613     2018-11-15 15:42:36.613
ccc          9003         2018-11-15 15:43:36.613     2018-11-15 15:43:36.613

t2中的AnnouncementID是通过以下过程R_GetManageID生成的：

DECLARE @ManageID TABLE(ManageID INT)   
DECLARE @AnnouncementID int         

INSERT INTO @ManageID           
EXEC  R_GetManageID         

SET @AnnouncementID = (SELECT TOP 1 * FROM @ManageID)       
SELECT @AnnouncementID

我想将数据从t1插入到t2。

插入规则为：

如果t2中没有t1的记录，则将其插入到t2中，相关条件为t1.SupplyTitle = t2.SupplyTitle and t1.EmployeeCode = t2.EmployeeCode。
如果t2中存在t1记录，则只需更新t2.modified = getdate()。

这意味着t2的AnnouncementID仅在不满足相关条件时才生成@AnnouncementID。

例如，一开始，T2为空。

t1中的记录如下：

SupplyTitle  EmployeeCode  registered                 modified
    aaa          9001         2018-11-15 15:41:36.613     2018-11-15 15:41:36.613
    bbb          9002         2018-11-15 15:42:36.613     2018-11-15 15:42:36.613
    ccc          9003         2018-11-15 15:43:36.613     2018-11-15 15:43:36.613

如果@AnnouncementID的初始值为1001，则每次将此值加1。

然后在t2中生成的记录如下：

SupplyTitle  EmployeeCode AnnouncementID     registered                 modified
aaa          9001         1001       2018-11-19 12:00:00.000     2018-11-19 12:00:00.000
bbb          9002         1002       2018-11-19 12:00:00.000     2018-11-19 12:00:00.000
ccc          9003         1003       2018-11-19 12:00:00.000     2018-11-19 12:00:00.000

然后将t1中的记录更改为此：

SupplyTitle  EmployeeCode  registered                 modified
aaa          9001         2018-11-15 15:41:36.613     2018-11-15 15:41:36.613
bbb          9002         2018-11-15 15:42:36.613     2018-11-15 15:42:36.613
www          9008         2018-11-15 15:43:36.613     2018-11-15 15:43:36.613

所以t2中的记录应该像这样添加一行：

SupplyTitle  EmployeeCode AnnouncementID     registered                 modified
aaa          9001         1001       2018-11-19 12:00:00.000     2018-11-19 12:00:00.000
bbb          9002         1002       2018-11-19 12:00:00.000     2018-11-19 12:30:00.000
ccc          9003         1003       2018-11-19 12:00:00.000     2018-11-19 12:30:00.000
www          9008         1004       2018-11-19 12:30:00.000     2018-11-19 12:30:00.000

前2条记录的modified已更改。

那么我怎么能像这样插入（更新）t2？

Answer 1

使用MERGE可帮助您同步两个表，如下所示：

merge t2 as t
using t1 as s
on
(
    t.SupplyTitle = s.SupplyTitle
    and
        t.EmployeeCode = s.EmployeeCode
)
when matched then
    update
    set
        t.registered = s.registered, --any other data
        t.modified = s.modified,
        t.AnnouncementID = 0--'your_data'
when not matched by target then
    insert
        (
            SupplyTitle,
            EmployeeCode,
            AnnouncementID,
            registered,
            modified
        )
    values
        (
            s.SupplyTitle,
            s.EmployeeCode,
            0,--'your_data',
            s.registered,
            s.modified
        )

output $action, 
       deleted.SupplyTitle      as target_SupplyTitle, 
       deleted.EmployeeCode     as target_EmployeeCode, 
       deleted.registered       as target_registered,
       deleted.modified         as target_modified,
       inserted.SupplyTitle     as source_SupplyTitle, 
       inserted.EmployeeCode    as source_EmployeeCode, 
       inserted.registered      as source_registered,
       inserted.modified        as source_modified;

看看Reference Link以了解其工作原理。

如果记录不存在，则生成AnnouncementID；如果记录不存在，则不生成AnnouncementID，该怎么办？

1 个答案: