fix(mssql): map bare Stddev to stdev, not stdevp - #12083
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T-SQL STDEV is the sample deviation and STDEVP the population one, so round-tripping raw SQL through Backend.sql() silently changed which statistic was computed. sge.Variance three lines below already maps to the sample function. Our own compilation never emits a bare Stddev, it goes through stddev_samp/stddev_pop, so only raw SQL was affected.
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Closes #12057.
sqlglot.transpile("SELECT STDEV([x]) FROM [t]", read=MSSQL, write=MSSQL)returnsSTDEVP— sample in, population out.sge.Variancethree lines below already mapsto
var, the sample function, so this reads as a typo rather than a decision.Our own compilation never emits a bare
Stddev(it goes throughstddev_samp/stddev_pop), so only raw SQL throughBackend.sql()was affected. Test round-tripsthe four functions through the dialect, no backend needed.
Oracle's
Stddevand MySQL'sVariancelook like the same mismatch. Left alone —tell me if you want them in a follow-up.