我有三个表,表1,表2和表3.表1记录了所有现有记录,表2记录了要应用于表1的增量(新更新)。
表3是结果表。
表1和表3结构:ID是主键 身份证,日期,地点,年龄,人数
表2结构:ID是主键 ID,日期,地点,年龄,计数,ChangeType
表2仅记录表1中更改的字段的新更新值。
例如:
表1
1, 03/03/2017, A, 11, 1
2, 01/03/2017, B, 39, 1
3, 01/01/2017, D, 1, 1
表2
2, 03/03/2017,NULL, NULL,2, Update
1, NULL, CC, NULL, NULL, Update
因此表3应为
1, 03/03/2017, CC, 11, 1
2, 03/03/2017, B, 39, 2
3, 01/01/2017, D, 1, 1
任何建议都将不胜感激。
GO
/****** Object: Table [dbo].[Table_1] Script Date: 03/03/2017 10:41:28 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Table_1](
[ID] [int] NOT NULL,
[date] [date] NULL,
[location] [nvarchar](50) NULL,
[age] [int] NULL,
[count] [int] NULL
) ON [PRIMARY]
GO
/****** Object: Table [dbo].[Table_2] Script Date: 03/03/2017 10:41:28 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Table_2](
[ID] [int] NOT NULL,
[date] [date] NULL,
[location] [nvarchar](50) NULL,
[age] [int] NULL,
[count] [int] NULL,
[ChangeTyppe] [nvarchar](10) NULL
) ON [PRIMARY]
GO
/****** Object: Table [dbo].[Table_3] Script Date: 03/03/2017 10:41:28 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Table_3](
[ID] [int] NOT NULL,
[date] [date] NULL,
[location] [nvarchar](50) NULL,
[age] [int] NULL,
[count] [int] NULL
) ON [PRIMARY]
GO
INSERT [dbo].[Table_1] ([ID], [date], [location], [age], [count]) VALUES (1, CAST(0x863C0B00 AS Date), N'A', 11, 1)
GO
INSERT [dbo].[Table_1] ([ID], [date], [location], [age], [count]) VALUES (2, CAST(0x843C0B00 AS Date), N'B', 39, 1)
GO
INSERT [dbo].[Table_1] ([ID], [date], [location], [age], [count]) VALUES (3, CAST(0x493C0B00 AS Date), N'D', 1, 1)
GO
INSERT [dbo].[Table_2] ([ID], [date], [location], [age], [count], [ChangeTyppe]) VALUES (2, CAST(0x863C0B00 AS Date), NULL, NULL, 2, N'Update')
GO
INSERT [dbo].[Table_2] ([ID], [date], [location], [age], [count], [ChangeTyppe]) VALUES (1, NULL, N'CC', NULL, NULL, N'Update')
GO
答案 0 :(得分:2)
如果您只需要一次性的话,那么这应该可行。
Left连接主键上的两个表,如果它不为null,则从T2获取值。如果2的值为空,则从T1获取值。
Coalesce将返回第一个非空值。
如果T2中的行不存在,或者T2中的值为空 - 每个ID,T2中的值将为空。
INSERT dbo.Table_3
( ID, date, location, age, count )
SELECT t1.ID ,
[date] = COALESCE(t2.date, t1.date) ,
[location] = COALESCE(t2.location, t1.location) ,
[age] = COALESCE(t2.age, t1.age) ,
[count] = COALESCE(t2.count, t1.count)
FROM dbo.Table_1 t1
LEFT OUTER JOIN dbo.Table_2 t2 ON t2.ID = t1.ID