Find matching records in same table different columns - tsql

Question

I have this query:
SELECT
TLOCMTR.LOCATN_K, TLOCMTR.MTR_SRP_N, TLOCMTR.MTR_INST_D,
TLOCMTR.MTR_XCHG_OUT_D, RATE.RATE, TMTR.MTR_MFR_MOD_C,
TMTR.MTR_MFR_NM_CD
FROM
TMTR
RIGHT OUTER JOIN
TLOCMTR ON TMTR.MTR_SRP_N = TLOCMTR.MTR_SRP_N
LEFT OUTER JOIN
RATE ON TLOCMTR.LOCATN_K = RATE.LOCATN_K
WHERE
((RATE.RATE >= 20) AND (RATE.RATE <= 29))
AND TLOCMTR.MTR_INST_D >= '2014-01-01'
ORDER BY
LOCATN_K, MTR_INST_D
The code results in:
What I need to do is count the number of times the MTR_MFR_NM_CD changes from AMP to <>AMP per Locatn_K where the MTR_INST_D = MTR_XCHG_OUT_D. For example LOCATN_K = 85420005 went from AMP to EEM and the MTR_XCHG_D = MTR_INST_D 1 time (date was '2014-08-27'. LOCATN_K 85430001 went from AMP to EEM 2 times on dates '2015-01-05' and '2016-01-12.
Please help me with some T-SQL to answer this!

Answer 1

this is the essentials
select *
from ( select LOCATN_K, MTR_INST_D, MTR_MFR_NM_CD
, LEAD(MTR_MFR_NM_CD, 1,0) OVER (PARTITTION LOCATN_K BY ORDER BY MTR_INST_D) AS MTR_MFR_NM_CD_NEXT
from
...
) tt
where MTR_MFR_NM_CD = 'AMP'
and MTR_MFR_NM_CD_NEXT <> 'AMP'

Answer 2

I tried Frisbee's code with the following modifications but did not get the exact results:
select *
from ( select TLOCMTR.LOCATN_K, TLOCMTR.MTR_SRP_N, TLOCMTR.MTR_INST_D, TLOCMTR.MTR_XCHG_OUT_D, TMTR.MTR_MFR_MOD_C, TMTR.MTR_MFR_NM_CD,
LEAD(TMTR.MTR_MFR_NM_CD, 1,0) OVER (PARTITION BY TLOCMTR.LOCATN_K
ORDER BY MTR_INST_D) AS MTR_MFR_NM_CD_NEXT
FROM TMTR RIGHT OUTER JOIN TLOCMTR ON TMTR.MTR_SRP_N = TLOCMTR.MTR_SRP_N
LEFT OUTER JOIN RATE ON TLOCMTR.LOCATN_K = RATE.LOCATN_K
WHERE ((RATE.RATE >= 20) AND (RATE.RATE <= 29)) AND TLOCMTR.MTR_INST_D>='2014-01-01' AND TMTR.MTR_MFR_NM_CD = 'AMP'
) tt
where tt.MTR_MFR_NM_CD = 'AMP'
and tt.MTR_MFR_NM_CD_NEXT <> 'AMP'
order by tt.LOCATN_K
This resulted in getting 'Amp' to 'Amp' and <>'Amp' to 'Amp', but what I just wanted to get was 'Amp'to <>'Amp'.
The easiest way for me to do this was:
WITH A AS
(SELECT TLOCMTR.LOCATN_K, TLOCMTR.MTR_SRP_N, TLOCMTR.MTR_XCHG_OUT_D, TMTR.MTR_MFR_MOD_C, TMTR.MTR_MFR_NM_CD
FROM TMTR RIGHT OUTER JOIN TLOCMTR ON TMTR.MTR_SRP_N = TLOCMTR.MTR_SRP_N LEFT OUTER JOIN RATE ON TLOCMTR.LOCATN_K = RATE.LOCATN_K
WHERE ((RATE.RATE >= 20) AND (RATE.RATE <= 29)) and TLOCMTR.MTR_INST_D>='2014-01-01' AND TMTR.MTR_MFR_NM_CD = 'AMP'
),
B AS(
SELECT TLOCMTR.LOCATN_K, TLOCMTR.MTR_SRP_N, TLOCMTR.MTR_INST_D, TMTR.MTR_MFR_MOD_C, TMTR.MTR_MFR_NM_CD
FROM TMTR RIGHT OUTER JOIN TLOCMTR ON TMTR.MTR_SRP_N = TLOCMTR.MTR_SRP_N
LEFT OUTER JOIN RATE ON TLOCMTR.LOCATN_K = RATE.LOCATN_K
WHERE ((RATE.RATE >= 20) AND (RATE.RATE <= 29)) AND TLOCMTR.MTR_INST_D>='2014-01-01' AND TMTR.MTR_MFR_NM_CD <> 'AMP'
)
SELECT A.LOCATN_K, A.MTR_SRP_N AmpyMeter, B.MTR_SRP_N CreditMeter, B.MTR_INST_D EXCG_DT, A.MTR_MFR_MOD_C AMP_MODEL, B.MTR_MFR_MOD_C Credit_MODEL
FROM A inner join B on A.MTR_XCHG_OUT_D = B.MTR_INST_D and A.LOCATN_K=B.LOCATN_K
ORDER BY LOCATN_K
My final results look like: