.5NestedLoop.5MergeJoin.5RicCC.5通往性能优化的天堂-地狱 JOIN方法说明.5):
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NestedLoop:
  foreach rowA in tableA where tableA.col2=?
    {
    search rowsB from tableB where tableB.col1=rowA.col1 and tableB.col2=? ;
    if(rowsB.Count<=0)
        discard rowA ;
    else
        output rowA and rowsB ;
    }
MergeJoin:
.5merge join.5
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.5NestedLoop.5MergeJoin.5
.5A.5B.5m.5n.5m < n.5a.5b.5A.5B.5A.col1.5B.col1.5
select A.col1, B.col2 from A inner join B where A.col1 = B.col1.5

.5NestedLoop.5.5
A.5outer input.5B.5inner input.5A.5IO.5a.5clustered index seek.53(.5IO.5a + 3*m.5B.5inner input.5A.5outer input.5
.5MergeJoin:
MergeJoin.5A.5B.5Scan.5Merge.5A.5B.5IO.5a + b.5IO.5

.5a + 3*m << a + b.53*m << b.5NestedLoop.5A.5B.5NestedLoop.5MergeJoin.5cpu.5

OK.5
.5charge.5charge_no.5int identity(1,1).510.5582.52.5A.5col1.5999.52.5min(A.col1) = min(charge.charge_no).5Max(A.col1) < max(charge.charge_no).5
我们在set statistics io on和set statistics time on之后，执行语句：

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.5999.5