今天，碰到一個(gè)怪問(wèn)題，同一個(gè)sql語(yǔ)句，運(yùn)行產(chǎn)生不同的結(jié)果，
SELECT?a.TAXPAYERID?TAXPAYERID$0,?a.INDEPOTYEAR?INDEPOTYEAR$2,?
SUM(a.TAXFINAL)?SUMTAXFINAL$1?
FROM?F_LVY_LEVYINPUTYEARHISTORYDATA?a?
WHERE?substr?(?a.TAXPAYERID?,1?,?1?)?'T'?and?a.indepotyear='2006'?GROUP?BY?a.TAXPAYERID,?a.INDEPOTYEAR?having?SUM(a.TAXFINAL)?>=1000000?第一次運(yùn)行產(chǎn)生1357條記錄，然后接著運(yùn)行就變?yōu)?359（此為正確數(shù)），到網(wǎng)上找了下，沒(méi)有找到原因， 最后把substr ( a.TAXPAYERID ,1 , 1 ) 'T' 改為 a.TAXPAYERID not like 'T%'沒(méi)有問(wèn)題，把上面sql改為
SELECT?a.TAXPAYERID?TAXPAYERID$0,?a.INDEPOTYEAR?INDEPOTYEAR$2,?SUM(a.TAXFINAL)?SUMTAXFINAL$1?FROM?F_LVY_LEVYINPUTYEARHISTORYDATA?a?WHERE?a.indepotyear='2006'?GROUP?BY?a.TAXPAYERID,?a.INDEPOTYEAR?having?SUM(a.TAXFINAL)?>=1000000?and?substr?(?a.TAXPAYERID?,1?,?1?)?'T'? 也沒(méi)有問(wèn)題， 而所有記錄中substr ( a.TAXPAYERID ,1 , 1 )只有三種0,1,T, a.TAXPAYERID沒(méi)有為空的，不清楚為何如此？？