从SQL查询中的字符串中间提取数据

Question

I currently have a SQL query that is displaying several columns of data. In one of those columns I would like to pare down the data to only display what is really needed. The problem is the data I want is in the middle of string. I know what is before the value I need and what is after that is a fixed constant. The rest of the string may change. Is there a way in a SQL query to only display that data?

Below is an example of the data in the string. I would like to only see the data between the LR and SCCM.

A   %VR1  P  P%V 104.922043 %      Pt 4.902552 psig       PLR2  P  LR **0.350922** sccm      PL 0.001313 dpsig   

R   %VR1  P  P%V 105.017807 %      Pt 4.934245 psig       PLR2  F  LR **5.366095** sccm      PL 0.014557 dpsig     

A   %VR1  P  P%V 100.644852 %      Pt 5.112900 psig       PLR2  P  LR **-0.029057** sccm     PL 0.000377 dpsig     

A   %VR1  P  P%V 101.631256 %      Pt 5.107606 psig       PLR2  P  LR **2.515130** sccm      PL 0.006896 dpsig       

Answer 1

SQL引擎具有SUBSTR（）或SUBSTRING（）函数，如果您始终需要跳过前2个字符和后4个字符，它们将满足您的需要。

Answer 2

If you are using SQL Server

declare @String varchar(500)

set @String = 'A %VR1 P P%V 101.631256 % Pt 5.107606 psig PLR2 P LR 2.515130 sccm PL 0.006896 dpsig '

select SUBSTRING(@String, charindex('PLR2 P LR ', @String) + 10, charindex(' sccm PL', @String) - charindex('PLR2 P LR ', @String) - 10)

If you are sure about the LR and sccm being unique you could use:

declare @String varchar(500)

set @String = 'A %VR1 P P%V 101.631256 % Pt 5.107606 psig PLR2 P LR 2.515130 sccm PL 0.006896 dpsig '

select SUBSTRING(@String, charindex('LR ', @String) + 3, charindex(' sccm', @String) - charindex('LR ', @String) - 3)

Answer 3

MySQL Version:

SET @var = 'A %VR1 P P%V 104.922043 % Pt 4.902552 psig PLR2 P LR 0.350922 sccm PL 0.001313 dpsig';

SELECT SUBSTRING(@var, LOCATE('LR ', @var) + 3, LOCATE('sccm', @var) - LOCATE('LR ', @var) - 3)

Result

0.350922

SQL Server Version:

DECLARE @var varchar(200)
SET @var = 'A %VR1 P P%V 104.922043 % Pt 4.902552 psig PLR2 P LR 0.350922 sccm PL 0.001313 dpsig'

SELECT SUBSTRING(@var, CHARINDEX('LR ', @var) + 3, CHARINDEX('sccm', @var) - CHARINDEX('LR ', @var) - 3)

Result

0.350922

With a column name:

SELECT SUBSTRING(col1, CHARINDEX('LR ', col1) + 3, CHARINDEX('sccm', col1) - CHARINDEX('LR ', col1) - 3)