[Therion] Every Survey with data has 2 centrelines?

[Andrew Atkinson]

Hello

I was just wondering if this is correct, but it would appear that when 
searching the database output all surveys contain at least 2 centreline ids

Attached is the Forbidden.th file which has only one 
centreline/endcentreline pair, but the result below seems to show that 
there are 2 centreline id per survey when there is a 
centreline/endcentreline, of which one always have zero length. There is 
one id in files where there are no centreline/endcentreline, Eg 
CheddarCatchment which is the file that puts it all together, again this 
has zero length.

This could be the way that it is designed, but it does seem to lead to 
lots of redundant data.

Here is the search (I added the names in for ease of reference)

SELECT C.`TITLE`, C.`ID`, C.SURVEY_ID, SURVEY.NAME, C.`SURFACE_LENGTH`, 
C.`LENGTH`
FROM CENTRELINE C, SURVEY
where SURVEY.ID=C.SURVEY_ID Limit 30

which gives this result (also attached as csv, as email can make a mess 
of tables)

TITLE	ID	SURVEY_ID	NAME	SURFACE_LENGTH	LENGTH	
	2	1		0	0	
	12	11	CheddarCatchment	0	0	
	14	13	Blackmoor	0	0	
	15	13	Blackmoor	0	105.3	
	18	17	BoneHole	0	0	
	20	19	BH_Surface	0	0	
	21	19	BH_Surface	13.49	0	
	22	19	BH_Surface	110.86	0	
	25	24	BH_Entrance	0	0	
	26	24	BH_Entrance	0	26.77	
	29	28	BH_FirstPitch	0	0	
	30	28	BH_FirstPitch	0	23.23	
	33	32	BH_PerforationChoke	0	0	
	34	32	BH_PerforationChoke	0	41.57	
	37	36	Bone2	0	0	
	38	36	Bone2	0	65.52	
	42	41	Box	0	0	
	43	41	Box	0	55.96	
	46	45	charter	0	0	
	48	47	OldCave	0	0	
	50	49	Chiaroscuro	0	0	
	180	49	Chiaroscuro	0	89.01	
	183	182	Entrance	0	0	
	616	182	Entrance	0	103.07	
	617	182	Entrance	0	281.2	
	620	619	Forbidden	0	0	
	720	619	Forbidden	0	36.84	
	723	722	Midsummer	0	0	
	812	722	Midsummer	0	31.38	
	815	814	ReadsInlet	0	0	
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