强制实施计划方案：使用 USE PLAN 强制实施 JOIN 算法
此示例强制 SQL Server 使用指定将内部联接逻辑运算符和合并联接物理运算符用于查询的计划。
示例
USE tempdb;
GO
CREATE TABLE t1(i INT)
CREATE TABLE t2(j INT)
GO
SELECT * FROM t1, t2 WHERE t1.i = t2.j OPTION (USE PLAN N'
<ShowPlanXML xmlns="https://schemas.microsoft.com/sqlserver/2004/07/showplan" Version="0.5" Build="9.00.938">
<BatchSequence>
<Batch>
<Statements>
<StmtSimple StatementText="SELECT * FROM t1, t2 WHERE t1.i = t2.j" StatementId="1"
StatementCompId="1" StatementType="SELECT" StatementSubTreeCost="0.0514796"
StatementEstRows="1" StatementOptmLevel="FULL">
<StatementSetOptions QUOTED_IDENTIFIER="true" ARITHABORT="true" CONCAT_NULL_YIELDS_NULL="true"
ANSI_NULLS="true" ANSI_PADDING="true" ANSI_WARNINGS="true" NUMERIC_ROUNDABORT="false" />
<QueryPlan CachedPlanSize="20">
<RelOp NodeId="0" PhysicalOp="Merge Join" LogicalOp="Inner Join" EstimateRows="1"
EstimateIO="0.000313" EstimateCPU="0.00564738" AvgRowSize="15"
EstimatedTotalSubtreeCost="0.0514796" Parallel="0" EstimateRebinds="0" EstimateRewinds="0">
<OutputList>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</OutputList>
<Merge ManyToMany="1">
<InnerSideJoinColumns>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</InnerSideJoinColumns>
<OuterSideJoinColumns>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</OuterSideJoinColumns>
<Residual>
<ScalarOperator ScalarString="[tempdb].[dbo].[t2].[j]=[tempdb].[dbo].[t1].[i]">
<Compare CompareOp="EQ">
<ScalarOperator>
<Identifier>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</Identifier>
</ScalarOperator>
<ScalarOperator>
<Identifier>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</Identifier>
</ScalarOperator>
</Compare>
</ScalarOperator>
</Residual>
<RelOp NodeId="1" PhysicalOp="Sort" LogicalOp="Sort" EstimateRows="1" EstimateIO="0.01625"
EstimateCPU="0.000100011" AvgRowSize="11" EstimatedTotalSubtreeCost="0.0227581" Parallel="0"
EstimateRebinds="0" EstimateRewinds="0">
<OutputList>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</OutputList>
<MemoryFractions Input="1" Output="0.5" />
<Sort Distinct="0">
<OrderBy>
<OrderByColumn Ascending="1">
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</OrderByColumn>
</OrderBy>
<RelOp NodeId="2" PhysicalOp="Table Scan" LogicalOp="Table Scan" EstimateRows="1"
EstimateIO="0.0063285" EstimateCPU="7.96e-005" AvgRowSize="11"
EstimatedTotalSubtreeCost="0.0064081" Parallel="0" EstimateRebinds="0"
EstimateRewinds="0">
<OutputList>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</OutputList>
<TableScan Ordered="0" ForcedIndex="0">
<DefinedValues>
<DefinedValue>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t1]" Column="i" />
</DefinedValue>
</DefinedValues>
<Object Database="[tempdb]" Schema="[dbo]" Table="[t1]" />
</TableScan>
</RelOp>
</Sort>
</RelOp>
<RelOp NodeId="3" PhysicalOp="Sort" LogicalOp="Sort" EstimateRows="1"
EstimateIO="0.01625" EstimateCPU="0.000100011" AvgRowSize="11"
EstimatedTotalSubtreeCost="0.0227581" Parallel="0" EstimateRebinds="0" EstimateRewinds="0">
<OutputList>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</OutputList>
<MemoryFractions Input="0.5" Output="0.5" />
<Sort Distinct="0">
<OrderBy>
<OrderByColumn Ascending="1">
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</OrderByColumn>
</OrderBy>
<RelOp NodeId="4" PhysicalOp="Table Scan" LogicalOp="Table Scan" EstimateRows="1"
EstimateIO="0.0063285" EstimateCPU="7.96e-005" AvgRowSize="11"
EstimatedTotalSubtreeCost="0.0064081" Parallel="0" EstimateRebinds="0"
EstimateRewinds="0">
<OutputList>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</OutputList>
<TableScan Ordered="0" ForcedIndex="0">
<DefinedValues>
<DefinedValue>
<ColumnReference Database="[tempdb]" Schema="[dbo]" Table="[t2]" Column="j" />
</DefinedValue>
</DefinedValues>
<Object Database="[tempdb]" Schema="[dbo]" Table="[t2]" />
</TableScan>
</RelOp>
</Sort>
</RelOp>
</Merge>
</RelOp>
</QueryPlan>
</StmtSimple>
</Statements>
</Batch>
</BatchSequence>
</ShowPlanXML>')