Sql server 如何保证某些行是唯一的（一种辅助键）SQL_Sql Server

Sql server 如何保证某些行是唯一的（一种辅助键）SQL

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Sql server 如何保证某些行是唯一的（一种辅助键）SQL,sql-server,Sql Server,在SQL中是否有生成辅助密钥的方法假设我有一个ID为SECID1、SECID2列的表密钥是ID，但我还希望SECID1、SECID2作为密钥工作，以保证我没有两个具有相同SECID1和SECID1的条目如果可能，如何执行此操作？是的，您可以在“我使用唯一约束”下面添加复合列唯一约束或唯一索引 CREATE TABLE YourTable ( ID INT PRIMARY KEY, SECID1 INT, SECID2 INT, UNIQUE(SECID1,SECID2) ) 是否确实

在SQL中是否有生成辅助密钥的方法

假设我有一个ID为SECID1、SECID2列的表

密钥是ID，但我还希望SECID1、SECID2作为密钥工作，以保证我没有两个具有相同SECID1和SECID1的条目

如果可能，如何执行此操作？

是的，您可以在“我使用唯一约束”下面添加复合列唯一约束或唯一索引

CREATE TABLE YourTable
(
ID INT PRIMARY KEY, 
SECID1 INT, 
SECID2 INT,
UNIQUE(SECID1,SECID2)
)

是否确实需要代理ID列？如果这是一个多对多关系表，则我通常只有一个2列PK，有时根据访问该表的查询的相反键顺序有一个唯一索引/约束

是，您可以在下面添加一个复合列唯一约束或唯一索引。我使用唯一约束

CREATE TABLE YourTable
(
ID INT PRIMARY KEY, 
SECID1 INT, 
SECID2 INT,
UNIQUE(SECID1,SECID2)
)

是否确实需要代理ID列？如果这是一个多对多关系表，我通常只有一个2列的PK，有时还有一个唯一的索引/约束，其键顺序与访问该表的查询相反

您可以创建任意多的唯一键约束，以实现此类唯一性检查/约束。

您可以创建任意多的唯一键约束由于您希望实现这种唯一性检查/约束。

这里有文档和说明：

有可能，这里有文档和说明：

您想要的是一个

1您可以使用或：

结果:

name                index_id type type_desc    is_unique is_primary_key
------------------- -------- ---- ------------ --------- --------------
PK_MyTestTable      1        1    CLUSTERED    1         1
UQ_MyTestTable_A_B  2        2    NONCLUSTERED 1         0
IUN_MyTestTable_A_B 3        2    NONCLUSTERED 1         0

name                    index_id    type type_desc    is_unique is_primary_key is_disabled
----------------------- ----------- ---- ------------ --------- -------------- -----------
PK_MyTestTable          1           1    CLUSTERED    1         1              0
UQ_MyTestTable_A_B      2           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B     3           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B_#_C 4           2    NONCLUSTERED 1         0              0

Msg 2601, Level 14, State 1, Line 1
Cannot insert duplicate key row in object 'dbo.Invoice' with unique index 'IUF_Invoice_ParentInvoiceID'.
The statement has been terminated.

name               index_id    type type_desc     is_unique is_primary_key is_disabled
------------------ ----------- ---- ------------- --------- -------------- -----------
UQ_MyTestTable_A_B 1           1    CLUSTERED     1         0              0
PK_MyTestTable     2           2    NONCLUSTERED  1         1              0

name                 index_id    type type_desc    is_unique is_primary_key is_disabled
-------------------- ----------- ---- ------------ --------- -------------- -----------
IUN_MyTestTable_A_B2 1           1    CLUSTERED    1         0              0
PK_MyTestTable       2           2    NONCLUSTERED 1         1              0

注1：您可以看到约束PK_MyTestTable创建为聚集唯一索引，约束UQ_MyTestTable_A_B UNIQUE Noncustered创建为“非聚集索引”

注2 SQL 2008+：对于我来说，在SQL Server 2008中，唯一非聚集约束和唯一非聚集索引之间的主要区别在于能够：

结果:

name                index_id type type_desc    is_unique is_primary_key
------------------- -------- ---- ------------ --------- --------------
PK_MyTestTable      1        1    CLUSTERED    1         1
UQ_MyTestTable_A_B  2        2    NONCLUSTERED 1         0
IUN_MyTestTable_A_B 3        2    NONCLUSTERED 1         0

name                    index_id    type type_desc    is_unique is_primary_key is_disabled
----------------------- ----------- ---- ------------ --------- -------------- -----------
PK_MyTestTable          1           1    CLUSTERED    1         1              0
UQ_MyTestTable_A_B      2           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B     3           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B_#_C 4           2    NONCLUSTERED 1         0              0

Msg 2601, Level 14, State 1, Line 1
Cannot insert duplicate key row in object 'dbo.Invoice' with unique index 'IUF_Invoice_ParentInvoiceID'.
The statement has been terminated.

name               index_id    type type_desc     is_unique is_primary_key is_disabled
------------------ ----------- ---- ------------- --------- -------------- -----------
UQ_MyTestTable_A_B 1           1    CLUSTERED     1         0              0
PK_MyTestTable     2           2    NONCLUSTERED  1         1              0

name                 index_id    type type_desc    is_unique is_primary_key is_disabled
-------------------- ----------- ---- ------------ --------- -------------- -----------
IUN_MyTestTable_A_B2 1           1    CLUSTERED    1         0              0
PK_MyTestTable       2           2    NONCLUSTERED 1         1              0

您可以使用创建唯一的非聚集索引。。。包括从执行计划中创建并消除KeyLookup或RID Lookup

注3 SQL 2008+：此外，您可能有

结果:

name                index_id type type_desc    is_unique is_primary_key
------------------- -------- ---- ------------ --------- --------------
PK_MyTestTable      1        1    CLUSTERED    1         1
UQ_MyTestTable_A_B  2        2    NONCLUSTERED 1         0
IUN_MyTestTable_A_B 3        2    NONCLUSTERED 1         0

name                    index_id    type type_desc    is_unique is_primary_key is_disabled
----------------------- ----------- ---- ------------ --------- -------------- -----------
PK_MyTestTable          1           1    CLUSTERED    1         1              0
UQ_MyTestTable_A_B      2           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B     3           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B_#_C 4           2    NONCLUSTERED 1         0              0

Msg 2601, Level 14, State 1, Line 1
Cannot insert duplicate key row in object 'dbo.Invoice' with unique index 'IUF_Invoice_ParentInvoiceID'.
The statement has been terminated.

name               index_id    type type_desc     is_unique is_primary_key is_disabled
------------------ ----------- ---- ------------- --------- -------------- -----------
UQ_MyTestTable_A_B 1           1    CLUSTERED     1         0              0
PK_MyTestTable     2           2    NONCLUSTERED  1         1              0

name                 index_id    type type_desc    is_unique is_primary_key is_disabled
-------------------- ----------- ---- ------------ --------- -------------- -----------
IUN_MyTestTable_A_B2 1           1    CLUSTERED    1         0              0
PK_MyTestTable       2           2    NONCLUSTERED 1         1              0

2您可以使用或：

结果:

name                index_id type type_desc    is_unique is_primary_key
------------------- -------- ---- ------------ --------- --------------
PK_MyTestTable      1        1    CLUSTERED    1         1
UQ_MyTestTable_A_B  2        2    NONCLUSTERED 1         0
IUN_MyTestTable_A_B 3        2    NONCLUSTERED 1         0

name                    index_id    type type_desc    is_unique is_primary_key is_disabled
----------------------- ----------- ---- ------------ --------- -------------- -----------
PK_MyTestTable          1           1    CLUSTERED    1         1              0
UQ_MyTestTable_A_B      2           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B     3           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B_#_C 4           2    NONCLUSTERED 1         0              0

Msg 2601, Level 14, State 1, Line 1
Cannot insert duplicate key row in object 'dbo.Invoice' with unique index 'IUF_Invoice_ParentInvoiceID'.
The statement has been terminated.

name               index_id    type type_desc     is_unique is_primary_key is_disabled
------------------ ----------- ---- ------------- --------- -------------- -----------
UQ_MyTestTable_A_B 1           1    CLUSTERED     1         0              0
PK_MyTestTable     2           2    NONCLUSTERED  1         1              0

name                 index_id    type type_desc    is_unique is_primary_key is_disabled
-------------------- ----------- ---- ------------ --------- -------------- -----------
IUN_MyTestTable_A_B2 1           1    CLUSTERED    1         0              0
PK_MyTestTable       2           2    NONCLUSTERED 1         1              0

或

结果:

name                index_id type type_desc    is_unique is_primary_key
------------------- -------- ---- ------------ --------- --------------
PK_MyTestTable      1        1    CLUSTERED    1         1
UQ_MyTestTable_A_B  2        2    NONCLUSTERED 1         0
IUN_MyTestTable_A_B 3        2    NONCLUSTERED 1         0

name                    index_id    type type_desc    is_unique is_primary_key is_disabled
----------------------- ----------- ---- ------------ --------- -------------- -----------
PK_MyTestTable          1           1    CLUSTERED    1         1              0
UQ_MyTestTable_A_B      2           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B     3           2    NONCLUSTERED 1         0              0
IUN_MyTestTable_A_B_#_C 4           2    NONCLUSTERED 1         0              0

Msg 2601, Level 14, State 1, Line 1
Cannot insert duplicate key row in object 'dbo.Invoice' with unique index 'IUF_Invoice_ParentInvoiceID'.
The statement has been terminated.

name               index_id    type type_desc     is_unique is_primary_key is_disabled
------------------ ----------- ---- ------------- --------- -------------- -----------
UQ_MyTestTable_A_B 1           1    CLUSTERED     1         0              0
PK_MyTestTable     2           2    NONCLUSTERED  1         1              0

name                 index_id    type type_desc    is_unique is_primary_key is_disabled
-------------------- ----------- ---- ------------ --------- -------------- -----------
IUN_MyTestTable_A_B2 1           1    CLUSTERED    1         0              0
PK_MyTestTable       2           2    NONCLUSTERED 1         1              0