将一行分割成更多行 - 表转换

Question

我有一个应该转换为一个目标表的源表。源表包含四个带有传感器值的列。目的地表格应包含四行，一行传感器值，一行传感器编号 - 源表格中的每一行。换句话说，目标表将有四倍多的行。 （我相信这被称为标准化，至少，我认为未来将会使用更多或更少的或不同的传感器时更实际）。

更多背景信息来解释。我已经成功地尝试一个INSERT触发器，做，对于单行：

CREATE TRIGGER dbo.temperatures_to_sensors 
    ON dbo.Data 
    AFTER INSERT 
AS 
BEGIN 
    DECLARE @line_no TINYINT; 
    SET @line_no = 2;  -- hardwired for the production line 

    DECLARE @UTC DATETIME; 
    DECLARE @value1 FLOAT; 
    DECLARE @value2 FLOAT; 
    DECLARE @value3 FLOAT; 
    DECLARE @value4 FLOAT; 

    SELECT 
     @UTC = CAST((CAST(LEFT(inserted.UTC, 16) AS FLOAT) - 2415020.5) AS DATETIME), 
     @value1 = inserted.temperature_1, 
     @value2 = inserted.temperature_2, 
     @value3 = inserted.temperature_3, 
     @value4 = inserted.temperature_4 
    FROM inserted; 

    INSERT INTO dbo.line_sensor_values 
     (UTC, line_no, sensor_no, sensor_value) 
    VALUES (@UTC, @line_no, 1, @value1), 
     (@UTC, @line_no, 2, @value2), 
     (@UTC, @line_no, 3, @value3), 
     (@UTC, @line_no, 4, @value4); 
END; 
GO 

现在，我想从旧表初始化目标表一次。之后，触发器将继续填充值。我的SQL不好。我想：

CREATE PROCEDURE dbo.init_line_sensor_values 
AS 
BEGIN 
    DECLARE @line_no TINYINT; 
    SET @line_no = 2;  -- hardwired for the production line 

    DECLARE @UTC DATETIME; 
    DECLARE @value1 FLOAT; 
    DECLARE @value2 FLOAT; 
    DECLARE @value3 FLOAT; 
    DECLARE @value4 FLOAT; 

    INSERT INTO dbo.line_sensor_values 
     (UTC, line_no, sensor_no, sensor_value) 
    VALUES (@UTC, @line_no, 1, @value1), 
     (@UTC, @line_no, 2, @value2), 
     (@UTC, @line_no, 3, @value3), 
     (@UTC, @line_no, 4, @value4) 
    SELECT 
     @UTC = CAST((CAST(LEFT(t.UTC, 16) AS FLOAT) - 2415020.5) AS DATETIME), 
     @value1 = t.temperature_1, 
     @value2 = t.temperature_2, 
     @value3 = t.temperature_3, 
     @value4 = t.temperature_4 
    FROM dbo.Data AS t; 


END; 
GO 

EXECUTE dbo.init_line_sensor_values 
GO 

...但它失败

无法将NULL值插入列 'UTC'，表 '1000574.dbo.line_sensor_values';列不允许有空值。 INSERT失败。

很明显SELECT应该用不同的方式填入INSERT。或者我必须使用循环？ （光标创建和FETCH NEXT...和WHILE...）

修订

源表可以创建这样（简化）：

CREATE TABLE dbo.Data(
    UTC varchar(32) NOT NULL, 
    temperature_1 float NULL, 
    temperature_2 float NULL, 
    temperature_3 float NULL, 
    temperature_4 float NULL 

PRIMARY KEY CLUSTERED 
(
    UTC ASC 
) 
GO 

目标表创建这样：

CREATE TABLE dbo.line_sensor_values (
    UTC DATETIME NOT NULL, 
    line_no TINYINT NOT NULL, -- line number: 1, 2, 3, etc. 
    sensor_no TINYINT NOT NULL, -- sensor number: 1, 2, 3, etc. 
    sensor_value float NULL, -- the measured value 

    PRIMARY KEY CLUSTERED (
    UTC ASC, 
    line_no ASC, 
    sensor_no ASC 
) 
) 
GO 

感谢您的帮助，Petr

Answer 1

INSERT INTO dbo.line_sensor_value 
(UTC, line_no, sensor_no, sensor_value) 
select UTC, line_no, sensor_no, temperature_1 as sensor_value from dbo.Data 
union 
select UTC, line_no, sensor_no, temperature_2 as sensor_value from dbo.Data 
union 
select UTC, line_no, sensor_no, temperature_3 as sensor_value from dbo.Data 
union 
select UTC, line_no, sensor_no, temperature_4 as sensor_value from dbo.Data 

Answer 2

如果您只需要将具有四列的表格转换为单个表格，其中每行表示来自源表格和来自源表格的列的行号，则此处为示例：

这里是SQLFiddle

create table fourColumns 
(
    column1 varchar(50), 
    column2 varchar(50), 
    column3 varchar(50), 
    column4 varchar(50) 
) 

insert into fourColumns select 'A','B','C','D' 
insert into fourColumns select 'E','F','G','H' 

    ;with MyCTE (lineNumber, columnNumber, Result) 
as 
(
    select ROW_NUMBER() OVER(ORDER BY column1 ASC) AS Row, 1, column1 
    from fourColumns 
    union all 
    select ROW_NUMBER() OVER(ORDER BY column2 ASC) AS Row, 2, column2 
    from fourColumns 
    union all 
    select ROW_NUMBER() OVER(ORDER BY column3 ASC) AS Row, 3, column3 
    from fourColumns 
    union all 
    select ROW_NUMBER() OVER(ORDER BY column4 ASC) AS Row, 4, column4 
    from fourColumns   
) 
    -- add insert here 
select lineNumber, 
     columnNumber, 
     Result 
from MyCTE 
order by lineNumber