获取数据

Question

我有以下表格：

CREATE TABLE [dbo].[TurbinaGas5](
    [id] [int] IDENTITY(1,1) NOT NULL, 
    [id_central] [int] NULL, 
    [presion_agua_alta] [float] NULL, 
    [presion_agua_media] [float] NULL, 
    [presion_agua_baja] [float] NULL, 
    [temperatura_gases_entrando_tg] [float] NULL, 
    [fecha] [datetime] NOT NULL, 
    [Eficiencia_Camara_Combustion] [float] NULL, 
CONSTRAINT [PK_TurbinaGas5] PRIMARY KEY CLUSTERED 
(
    [id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 



CREATE TABLE [dbo].[TurbinaVapor7](
    [id] [int] IDENTITY(1,1) NOT NULL, 
    [id_central] [int] NULL, 
    [presion_vapor_alta] [float] NULL, 
    [presion_vapor_recalentado_caliente] [float] NULL, 
    [consumo_auxiliares] [float] NULL, 
    [potencia_neta_medida] [float] NULL, 
    [eficiencia_termica_bruta] [float] NULL, 
    [fecha] [datetime] NULL, 
CONSTRAINT [PK_TV7] PRIMARY KEY CLUSTERED 
(
    [id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

Database Diagram(sample)

这些表不relationated，altough他们没有相同的列，其数据以相同的日期时间戳记（费歇字段）保存。现在，我的问题是我想从两个表中选择一些由datetime过滤的字段（任何表的日期，因为它应该是相同的）。

也许你在问，你为什么不把所有的字段保存在同一张表中，因为它们被保存在同一时间戳？这是因为每个表包含近200个字段，并且它们属于工厂中的不同部分（这个项目是针对热电厂的）。

两个表仅共享字段：id_central作为外键。

我试图建立这样的查询：

select tg5.presion_agua_alta, tv7.flujo_vapor_alta from 
TurbinaGas5 tg5 inner join TurbinaVapor7 tv7 on tg5.id_central=tv7.id_central where tg5.fecha between CONVERT(DATETIME,'2017-04-18 01:50:00',102) and CONVERT(DATETIME,'2017-04-19 09:41:00',102) 

但这查询返回数百万行，并杀死了服务器。谢谢

例如，假设该表存储以下数据：

SET IDENTITY_INSERT [dbo].[TurbinaVapor7] ON 
INSERT [dbo].[TurbinaVapor7] ([id], [id_central], [presion_vapor_alta], [presion_vapor_recalentado_caliente], [consumo_auxiliares], [potencia_neta_medida], [eficiencia_termica_bruta], [fecha]) VALUES (11983, 1, 4, 5, 6, 7, 9, CAST(0x0000A75A0128A180 AS DateTime)) 
INSERT [dbo].[TurbinaVapor7] ([id], [id_central], [presion_vapor_alta], [presion_vapor_recalentado_caliente], [consumo_auxiliares], [potencia_neta_medida], [eficiencia_termica_bruta], [fecha]) VALUES (11985, 1, 9, 10, 11, 12, 13, CAST(0x0000A75A011826C0 AS DateTime)) 
SET IDENTITY_INSERT [dbo].[TurbinaVapor7] OFF 
/****** Object: Table [dbo].[TurbinaGas5] Script Date: 04/19/2017 18:29:50 ******/ 
SET IDENTITY_INSERT [dbo].[TurbinaGas5] ON 
INSERT [dbo].[TurbinaGas5] ([id], [id_central], [presion_agua_alta], [presion_agua_media], [presion_agua_baja], [temperatura_gases_entrando_tg], [fecha], [Eficiencia_Camara_Combustion]) VALUES (12024, 1, 1, 2, 3, 4, CAST(0x0000A75A0128A180 AS DateTime), 5) 
INSERT [dbo].[TurbinaGas5] ([id], [id_central], [presion_agua_alta], [presion_agua_media], [presion_agua_baja], [temperatura_gases_entrando_tg], [fecha], [Eficiencia_Camara_Combustion]) VALUES (12029, 1, 3, 4, 5, 6, CAST(0x0000A75A01391C40 AS DateTime), 7) 
SET IDENTITY_INSERT [dbo].[TurbinaGas5] OFF 

我想获得这两个表是在CADA containend 2017年4月19日之间的18：00：00.000和2017年4月19日19：00：00.000

希望你能帮助我，谢谢

Answer 1

如果你需要数据的每一行，是否有在其他表中的匹配行，你应该做的FULL OUTER JOIN与[id_central]和[fecha]。对于只有与[fecha]值匹配的行，请使用内部联接。您的查询会是这个样子，这取决于它到底是什么，你需要：

-- All rows with matching fecha 

select 
    tg5.presion_agua_alta, 
    tv7.flujo_vapor_alta 
from TurbinaGas5 tg5 
inner join TurbinaVapor7 tv7 
    on tg5.id_central=tv7.id_central 
    AND tg5.fecha = tv7.fecha 
where tg5.fecha between CONVERT(DATETIME,'2017-04-18 01:50:00',102) and CONVERT(DATETIME,'2017-04-19 09:41:00',102) 


-- All rows from TurbinaGas5, and any with matching fecha in TurbinaVapor7 

select 
    tg5.presion_agua_alta, 
    tv7.flujo_vapor_alta 
from TurbinaGas5 tg5 
LEFT join TurbinaVapor7 tv7 
    on tg5.id_central=tv7.id_central 
    AND tg5.fecha = tv7.fecha 
where tg5.fecha between CONVERT(DATETIME,'2017-04-18 01:50:00',102) and CONVERT(DATETIME,'2017-04-19 09:41:00',102) 


-- All rows in both tables, matching fecha on the same row 

select 
    tg5.presion_agua_alta, 
    tv7.flujo_vapor_alta 
from TurbinaGas5 tg5 
FULL OUTER join TurbinaVapor7 tv7 
    on tg5.id_central=tv7.id_central 
    AND tg5.fecha = tv7.fecha 
where tg5.fecha between CONVERT(DATETIME,'2017-04-18 01:50:00',102) and CONVERT(DATETIME,'2017-04-19 09:41:00',102) 
    or tv7.fecha between CONVERT(DATETIME,'2017-04-18 01:50:00',102) and CONVERT(DATETIME,'2017-04-19 09:41:00',102) 

希望这会有所帮助。