import excel "D:\Stata13\gsyh.xls", sheet("TRD_Dalyr") firstrow

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. save r1,replace
file r1.dta saved

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. sort  Trddt

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. save,replace
file r1.dta saved

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. merge m:1 Trddt using mr1, uniqusing
option uniqusing not allowed
r(198);

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. drop if _merge!=3
_merge not found
r(111);

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. save merg_market,replace
file merg_market.dta saved

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. drop _merge
variable _merge not found
r(111);

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. export excel using "D:\Stata13\scsyl.xlsx", firstrow(variables) replace
file D:\Stata13\scsyl.xlsx saved

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. gen r11=r1-0.05
(2 missing values generated)

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. gen mr11=mr1-0.05
mr1 not found
r(111);

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. reg r11 mr11,nocon
variable mr11 not found
r(111);