数据库：MSSQL server 2012;
隔离级别：READ_COMMITTED_SNAPSHOT
现在我有一张表“COV_HOLES_PERIODDATE”。它有一个复合主键，也是一个聚簇索引。此表上没有其他索引。
有许多线程（通过Java）同时工作。每个线程将首先通过锁定提示（updlock，rowlock）对DIFFERENT主键执行“select for update”，然后执行一些工作，然后更新此行的表。从Java方面可以保证每个线程在该表的不同行上运行。
然而，有一个罕见且难以捉摸的僵局，我无法一致地重现。这种僵局很快就会发生一次。我认为应该永远不会有锁争用，因为每个事务应该只锁定不同的行。死锁图表显示“密钥锁定”中的“冲突”。正如我所查询的，死锁图中的“Hobt id”是此表中的“索引”。
我错过了什么？谢谢！
每个tran的代码清单：注意每个tran对不同的主键进行操作。
begin tran;
select DIVISION_ID
from COV_HOLES_PERIODDATE with (updlock, rowlock)
where composite_primary_key = xxx;
//some work on other tables, not related to this table.
update COV_HOLES_PERIODDATE
set non_primaryKey_field= xxx
where composite_primary_key = xxx;
commit;
编辑3：来自SQL Server Profiler在我的Java负载测试程序运行时捕获的执行计划，如果我正确读取它，由于隐式转换，“skill =”已更改为“技能”介于“in”Seek Predicates“范围内”如图所示。但我不知道怎么解释它仍然是一个“Clustered Index Seek”，虽然这个图像中的“Seek Predicates”显示了“Skill”列的范围？
http://i.stack.imgur.com/9vThc.png
预期sql的代码清单（但执行计划显示“技能”列中的隐式转换更改“技能”部分）
选择DIVISION_ID
来自cpq_jfu_v4_speedTest.cpqjfuv4speedTest.COV_HOLES_PERIODDATE with（updlock，rowlock）
其中DIVISION_ID = 1
和UNIT_ID = 2
和SKILL ='M'
和PERIOD_START_DATE ='2014-02-09';
编辑2 ：第一个链接是死锁的图片。第二个链接是表及其索引 http://i.stack.imgur.com/8j6V9.png http://i.stack.imgur.com/JaFkl.png
编辑1 ：列出死锁图
<deadlock-list>
<deadlock victim="process2fb02d498">
<process-list>
<process id="process2fb02d498" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (425c06b927a8)" waittime="4321" ownerId="181788" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.930" XDES="0x2f0d6a3a8" lockMode="U" schedulerid="4" kpid="8704" status="suspended" spid="60" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-02-18T14:29:09.010" lastbatchcompleted="2014-02-18T14:29:09.010" lastattention="1900-01-01T00:00:00.010" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181788" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="148" sqlhandle="0x02000000f9bd1c3532128f75b67ae477b2447ba2a64528db0000000000000000000000000000000000000000">
update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 nvarchar(4000),@P1 smallint,@P2 smallint,@P3 nvarchar(4000),@P4 date)update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </inputbuf>
</process>
<process id="process2f0110cf8" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (3d51ccbaf870)" waittime="4303" ownerId="181789" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.933" XDES="0x2f651e6c8" lockMode="U" schedulerid="3" kpid="904" status="suspended" spid="56" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-02-18T14:29:09.030" lastbatchcompleted="2014-02-18T14:29:09.030" lastattention="1900-01-01T00:00:00.030" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181789" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="148" sqlhandle="0x02000000f9bd1c3532128f75b67ae477b2447ba2a64528db0000000000000000000000000000000000000000">
update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 nvarchar(4000),@P1 smallint,@P2 smallint,@P3 nvarchar(4000),@P4 date)update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </inputbuf>
</process>
<process id="process2f05d0188" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (f40d3be1c4a7)" waittime="4381" ownerId="181790" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.937" XDES="0x2f0290d08" lockMode="U" schedulerid="4" kpid="5248" status="suspended" spid="59" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2014-02-18T14:29:08.950" lastbatchcompleted="2014-02-18T14:29:08.950" lastattention="1900-01-01T00:00:00.950" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181790" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="110" sqlhandle="0x02000000e59aa71c628d78d0574a5f60f697c8ffd8228e4b0000000000000000000000000000000000000000">
select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 smallint,@P1 smallint,@P2 nvarchar(4000),@P3 date)select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </inputbuf>
</process>
<process id="process2f2a9f868" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (8b00f1e21b7f)" waittime="4380" ownerId="181792" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.950" XDES="0x2f651f1d8" lockMode="U" schedulerid="2" kpid="7652" status="suspended" spid="63" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2014-02-18T14:29:08.950" lastbatchcompleted="2014-02-18T14:29:08.950" lastattention="1900-01-01T00:00:00.950" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181792" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="110" sqlhandle="0x02000000e59aa71c628d78d0574a5f60f697c8ffd8228e4b0000000000000000000000000000000000000000">
select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 smallint,@P1 smallint,@P2 nvarchar(4000),@P3 date)select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </inputbuf>
</process>
</process-list>
<resource-list>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2c70ba180" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f2a9f868" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2fb02d498" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cc3d9980" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f05d0188" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f0110cf8" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cf4fa480" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f0110cf8" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f05d0188" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cf4f9e80" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2fb02d498" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f2a9f868" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
</resource-list>
</deadlock>
<deadlock victim="process2f0110cf8">
<process-list>
<process id="process2fb02d498" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (425c06b927a8)" waittime="4321" ownerId="181788" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.930" XDES="0x2f0d6a3a8" lockMode="U" schedulerid="4" kpid="8704" status="suspended" spid="60" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-02-18T14:29:09.010" lastbatchcompleted="2014-02-18T14:29:09.010" lastattention="1900-01-01T00:00:00.010" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181788" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="148" sqlhandle="0x02000000f9bd1c3532128f75b67ae477b2447ba2a64528db0000000000000000000000000000000000000000">
update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 nvarchar(4000),@P1 smallint,@P2 smallint,@P3 nvarchar(4000),@P4 date)update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </inputbuf>
</process>
<process id="process2f0110cf8" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (3d51ccbaf870)" waittime="4303" ownerId="181789" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.933" XDES="0x2f651e6c8" lockMode="U" schedulerid="3" kpid="904" status="suspended" spid="56" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-02-18T14:29:09.030" lastbatchcompleted="2014-02-18T14:29:09.030" lastattention="1900-01-01T00:00:00.030" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181789" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="148" sqlhandle="0x02000000f9bd1c3532128f75b67ae477b2447ba2a64528db0000000000000000000000000000000000000000">
update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 nvarchar(4000),@P1 smallint,@P2 smallint,@P3 nvarchar(4000),@P4 date)update cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE set LAST_UPDATED_DTZ=@P0 where DIVISION_ID=@P1 and UNIT_ID=@P2 and SKILL=@P3 and PERIOD_START_DATE=@P4 </inputbuf>
</process>
<process id="process2f05d0188" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (f40d3be1c4a7)" waittime="4381" ownerId="181790" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.937" XDES="0x2f0290d08" lockMode="U" schedulerid="4" kpid="5248" status="suspended" spid="59" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2014-02-18T14:29:08.950" lastbatchcompleted="2014-02-18T14:29:08.950" lastattention="1900-01-01T00:00:00.950" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181790" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="110" sqlhandle="0x02000000e59aa71c628d78d0574a5f60f697c8ffd8228e4b0000000000000000000000000000000000000000">
select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 smallint,@P1 smallint,@P2 nvarchar(4000),@P3 date)select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </inputbuf>
</process>
<process id="process2f2a9f868" taskpriority="0" logused="0" waitresource="KEY: 6:72057594048413696 (8b00f1e21b7f)" waittime="4381" ownerId="181792" transactionname="implicit_transaction" lasttranstarted="2014-02-18T14:29:08.950" XDES="0x2f651f1d8" lockMode="U" schedulerid="2" kpid="7652" status="suspended" spid="63" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2014-02-18T14:29:08.950" lastbatchcompleted="2014-02-18T14:29:08.950" lastattention="1900-01-01T00:00:00.950" clientapp="Microsoft JDBC Driver for SQL Server" hostname="ACNU34794GD" hostpid="0" loginname="cpq_jfu_v380_speedTest_WEBAPP" isolationlevel="read committed (2)" xactid="181792" currentdb="6" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128058">
<executionStack>
<frame procname="adhoc" line="1" stmtstart="110" sqlhandle="0x02000000e59aa71c628d78d0574a5f60f697c8ffd8228e4b0000000000000000000000000000000000000000">
select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </frame>
<frame procname="unknown" line="1" sqlhandle="0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000">
unknown </frame>
</executionStack>
<inputbuf>
(@P0 smallint,@P1 smallint,@P2 nvarchar(4000),@P3 date)select DIVISION_ID from cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE with (updlock, rowlock) where DIVISION_ID =@P0 and UNIT_ID =@P1 and SKILL =@P2 and PERIOD_START_DATE =@P3 </inputbuf>
</process>
</process-list>
<resource-list>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2c70ba180" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f2a9f868" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2fb02d498" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cc3d9980" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f05d0188" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f0110cf8" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cf4fa480" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2f0110cf8" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f05d0188" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
<keylock hobtid="72057594048413696" dbid="6" objectname="cpq_jfu_v380_speedTest.cpqjfuv380speedTest.COV_HOLES_PERIODDATE" indexname="1" id="lock2cf4f9e80" mode="U" associatedObjectId="72057594048413696">
<owner-list>
<owner id="process2fb02d498" mode="U"/>
</owner-list>
<waiter-list>
<waiter id="process2f2a9f868" mode="U" requestType="wait"/>
</waiter-list>
</keylock>
</resource-list>
</deadlock>
</deadlock-list>
答案 0 :(得分：1)
评论中记录的调查导致以下答案：
您传入的参数与类型中的相应列不匹配。这导致隐式转换和聚簇索引上的范围搜索。 ＆＃34;寻求＆＃34;意味着将扫描索引的子集。它并不一定意味着单身人士的寻求。
索引第3列的范围搜索意味着查询从锁定角度完全忽略第4列上的过滤器。这可能导致多行被锁定。不一定是范围锁定，因为这些不在READ COMMITTED下。您是否还设置了锁定提示HOLDLOCK（或SERIALIZABLE）范围锁定。
其他尝试过的事情：
这是整个交易吗？触发器？索引视图（不应该 与给定的死锁图有关但谁知道？你能发帖吗？ 图表作为XML的某个地方？并且没有NC索引，对吧？你能 发布两个语句的查询计划？
为什么有些交易有trancount =＆＃34; 2＆＃34;。可能是你 错误的交易，以便他们延长？这可以解释 为什么每个tran可以采取多个锁。 Iow app bug。添加此IF @@ TRANCOUNT＆lt;＆gt; 1 ROLLBACK在运行时断言。重新运行你的负载 用这个断言进行测试。
是否存在隐式转换？我知道有，因为你 传入一个nvarchar（4000），但PK列不能有这么大 柱。这可能导致范围锁定。更改更新 从@ P2到CONVERT（CORRECT_COLUMN_TYPE_HERE，@ P2）来确保。 检查执行计划以确保CI查找仅使用 平等谓词。不是范围。
我将此添加到答案中，以便此问题的未来访问者可以了解如何调查此问题。
答案 1 :(得分：0)
ROWLOCK永远不会绝对保证只锁定您操作的特定行。这甚至在MSDN上声明：
锁提示获取行级锁的ROWLOCK，UPDLOCK和XLOCK可能会锁定索引键而不是实际的数据行。
由于你无法100％依赖它，可能会发生罕见的僵局。在您的情况下，您可以看到一个指向这种情况的键上存在死锁。
答案 2 :(得分：0)
如果这可以帮助任何人遇到类似的问题。
根本原因是，默认情况下，MSSQL JDBC驱动程序将String参数作为Unicode发送到数据库服务器。有一个参数sendStringParameterAsUnicode [true | false]，可以作为连接属性传递。但默认情况下，此属性设置为true（http://technet.microsoft.com/en-us/library/ms378988.aspx）。
如果未在连接字符串中传递sendStringParameterAsUnicode参数（默认设置为true），则jdbc驱动程序将参数定义为char为nchar，varchar为nvarchar，longvarchar为ntext。
对于使用CHAR，VARCHAR和LONGVARCHAR JDBC数据类型的正确性和最佳性能，应用程序应将sendStringParametersAsUnicode属性设置为＆＃34; false＆＃34;