Просмотр исходного текста страницы SQL Server/T-SQL Tutorial/Constraints/REFERENCES

== Making a Table be Self-Referencing==



   
  <!-- start source code -->
   
    <source lang="sql">
5>
6>    CREATE TABLE Employees
7>    (
8>       EmployeeID       int           IDENTITY  NOT NULL,
9>       FirstName        varchar(25)             NOT NULL,
10>       MiddleInitial    char(1)                 NULL,
11>       LastName         varchar(25)             NOT NULL,
12>       Title            varchar(25)             NOT NULL,
13>       SSN              varchar(11)             NOT NULL,
14>       Salary           money                   NOT NULL,
15>       PriorSalary      money                   NOT NULL,
16>       LastRaise AS Salary - PriorSalary,
17>       HireDate         smalldatetime           NOT NULL,
18>       TerminationDate  smalldatetime           NULL,
19>       ManagerEmpID     int                     NOT NULL,
20>       Department       varchar(25)             NOT NULL
21>    )
22>    GO
1>
2> EXEC sp_help Employees
3> GO
Name                                                                                                                             Owner
                                                          Type                            Created_datetime
-------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------
--------------------------------------------------------- ------------------------------- -----------------------
Employees                                                                                                                        dbo
                                                          user table                      2008-08-17 13:06:24.657

Column_name                                                                                                                      Type
                                                          Computed                            Length      Prec  Scale Nullable                            TrimTrailingBlanks                  FixedLenNu
llInSource                Collation
-------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------
--------------------------------------------------------- ----------------------------------- ----------- ----- ----- ----------------------------------- ----------------------------------- ----------
------------------------- --------------------------------------------------------------------------------------------------------------------------------
EmployeeID                                                                                                                       int
                                                          no                                            4 10    0     no                                  (n/a)                               (n/a)
                          NULL
FirstName                                                                                                                        varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
MiddleInitial                                                                                                                    char
                                                          no                                            1             yes                                 no                                  yes
                          SQL_Latin1_General_CP1_CI_AS
LastName                                                                                                                         varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Title                                                                                                                            varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
SSN                                                                                                                              varchar
                                                          no                                           11             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Salary                                                                                                                           money
                                                          no                                            8 19    4     no                                  (n/a)                               (n/a)
                          NULL
PriorSalary                                                                                                                      money
                                                          no                                            8 19    4     no                                  (n/a)                               (n/a)
                          NULL
LastRaise                                                                                                                        money
                                                          yes                                           8 19    4     yes                                 (n/a)                               (n/a)
                          NULL
HireDate                                                                                                                         smalldatetime
                                                          no                                            4             no                                  (n/a)                               (n/a)
                          NULL
TerminationDate                                                                                                                  smalldatetime
                                                          no                                            4             yes                                 (n/a)                               (n/a)
                          NULL
ManagerEmpID                                                                                                                     int
                                                          no                                            4 10    0     no                                  (n/a)                               (n/a)
                          NULL
Department                                                                                                                       varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Identity                                                                                                                         Seed                                     Increment
           Not For Replication
-------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------- ------------------------------
---------- -------------------
EmployeeID                                                                                                                                                              1
         1                   0
RowGuidCol
--------------------------------------------------------------------------------------------------------------------------------
No rowguidcol column defined.
Data_located_on_filegroup
--------------------------------------------------------------------------------------------------------------------------------
PRIMARY
The object "Employees" does not have any indexes, or you do not have permissions.
No constraints are defined on object "Employees", or you do not have permissions.
No foreign keys reference table "Employees", or you do not have permissions on referencing tables.
Table is referenced by views
--------------------------------------------------------------------------------------------------------------------------------
1>    ALTER TABLE Employees
2>       ADD CONSTRAINT PK_EmployeeID
3>       PRIMARY KEY (EmployeeID)
4> GO
1>
2> EXEC sp_help Employees
3> GO
Name                                                                                                                             Owner
                                                          Type                            Created_datetime
-------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------
--------------------------------------------------------- ------------------------------- -----------------------
Employees                                                                                                                        dbo
                                                          user table                      2008-08-17 13:06:24.657

Column_name                                                                                                                      Type
                                                          Computed                            Length      Prec  Scale Nullable                            TrimTrailingBlanks                  FixedLenNu
llInSource                Collation
-------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------
--------------------------------------------------------- ----------------------------------- ----------- ----- ----- ----------------------------------- ----------------------------------- ----------
------------------------- --------------------------------------------------------------------------------------------------------------------------------
EmployeeID                                                                                                                       int
                                                          no                                            4 10    0     no                                  (n/a)                               (n/a)
                          NULL
FirstName                                                                                                                        varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
MiddleInitial                                                                                                                    char
                                                          no                                            1             yes                                 no                                  yes
                          SQL_Latin1_General_CP1_CI_AS
LastName                                                                                                                         varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Title                                                                                                                            varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
SSN                                                                                                                              varchar
                                                          no                                           11             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Salary                                                                                                                           money
                                                          no                                            8 19    4     no                                  (n/a)                               (n/a)
                          NULL
PriorSalary                                                                                                                      money
                                                          no                                            8 19    4     no                                  (n/a)                               (n/a)
                          NULL
LastRaise                                                                                                                        money
                                                          yes                                           8 19    4     yes                                 (n/a)                               (n/a)
                          NULL
HireDate                                                                                                                         smalldatetime
                                                          no                                            4             no                                  (n/a)                               (n/a)
                          NULL
TerminationDate                                                                                                                  smalldatetime
                                                          no                                            4             yes                                 (n/a)                               (n/a)
                          NULL
ManagerEmpID                                                                                                                     int
                                                          no                                            4 10    0     no                                  (n/a)                               (n/a)
                          NULL
Department                                                                                                                       varchar
                                                          no                                           25             no                                  no                                  no
                          SQL_Latin1_General_CP1_CI_AS
Identity                                                                                                                         Seed                                     Increment
           Not For Replication
-------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------- ------------------------------
---------- -------------------
EmployeeID                                                                                                                                                              1
         1                   0
RowGuidCol
--------------------------------------------------------------------------------------------------------------------------------
No rowguidcol column defined.
Data_located_on_filegroup
--------------------------------------------------------------------------------------------------------------------------------
PRIMARY
index_name                                                                                                                       index_description
                                                                                                                                            index_keys





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------------------------------------------------------------------
PK_EmployeeID                                                                                                                    clustered, unique, primary key located on PRIMARY
                                                                                                                                            EmployeeID






constraint_type                                                                                                                                    constraint_name
                                                                            delete_action update_action status_enabled status_for_replication constraint_keys





-------------------------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------
--------------------------------------------------------------------------- ------------- ------------- -------------- ---------------------- ----------------------------------------------------------
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PRIMARY KEY (clustered)                                                                                                                            PK_EmployeeID
                                                                            (n/a)         (n/a)         (n/a)          (n/a)                  EmployeeID






No foreign keys reference table "Employees", or you do not have permissions on referencing tables.
Table is referenced by views
--------------------------------------------------------------------------------------------------------------------------------
1>
2> drop table Employees;
3> GO</source>
    
   

== ON UPDATE CASCADE ON DELETE NO ACTION==



   
  <!-- start source code -->
   
    <source lang="sql">
2> CREATE TABLE customer
3> (
4> cust_id      int            NOT NULL  IDENTITY  PRIMARY KEY,
5> cust_name    varchar(50)    NOT NULL
6> )
7> GO
1> CREATE TABLE orders
2> (
3> order_id    int        NOT NULL  IDENTITY  PRIMARY KEY,
4> cust_id     int        NOT NULL  REFERENCES customer(cust_id)
5>                        ON UPDATE CASCADE ON DELETE NO ACTION
6> )
7> GO
1>
2> EXEC sp_helpconstraint customer
3> GO
Object Name

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
customer


constraint_type                                                                                                                                    constraint_name
                                                                            delete_action update_action status_enabled status_for_replication constraint_keys





-------------------------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------
--------------------------------------------------------------------------- ------------- ------------- -------------- ---------------------- ----------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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--------------------------------------------------------------------
PRIMARY KEY (clustered)                                                                                                                            PK__customer__43A1D464
                                                                            (n/a)         (n/a)         (n/a)          (n/a)                  cust_id






Table is referenced by foreign key

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
master.dbo.orders: FK__orders__cust_id__4E1F62D7

1>
2> EXEC sp_helpconstraint orders
3> GO
Object Name

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
orders


constraint_type                                                                                                                                    constraint_name
                                                                            delete_action update_action status_enabled status_for_replication constraint_keys





-------------------------------------------------------------------------------------------------------------------------------------------------- -----------------------------------------------------
--------------------------------------------------------------------------- ------------- ------------- -------------- ---------------------- ----------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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--------------------------------------------------------------------
FOREIGN KEY                                                                                                                                        FK__orders__cust_id__4E1F62D7
                                                                            No Action     Cascade       Enabled        Is_For_Replication     cust_id






                                                                                                                                              REFERENCES master.dbo.customer (cust_id)





PRIMARY KEY (clustered)                                                                                                                            PK__orders__4D2B3E9E
                                                                            (n/a)         (n/a)         (n/a)          (n/a)                  order_id






No foreign keys reference table "orders", or you do not have permissions on referencing tables.
1>
2> drop table orders;
3> GO
1>
2></source>
    
   

== Primary key and foreign key==



   
  <!-- start source code -->
   
    <source lang="sql">
4> CREATE TABLE master_customer
5> (
6> cust_id      int            NOT NULL  IDENTITY  PRIMARY KEY,
7> cust_name    varchar(50)    NOT NULL
8> )
9> GO
1>
2>
3> CREATE TABLE customer_location
4> (
5> cust_id     int            NOT NULL,
6> cust_loc    smallint       NOT NULL,
7> CONSTRAINT PK_CUSTOMER_LOCATION PRIMARY KEY (cust_id,cust_loc),
8> CONSTRAINT FK_CUSTOMER_LOCATION FOREIGN KEY (cust_id)
9>     REFERENCES master_customer (cust_id)
10> )
11> GO
1>
2>
3> CREATE TABLE orders
4> (
5> order_id    int            NOT NULL  IDENTITY  PRIMARY KEY,
6>
7> cust_id     int            NOT NULL,
8> cust_loc    smallint       NOT NULL,
9> CONSTRAINT FK_ORDER_MASTER_CUST FOREIGN KEY (cust_id)
10>     REFERENCES master_customer (cust_id),
11> CONSTRAINT FK_ORDER_CUST_LOC FOREIGN KEY (cust_id, cust_loc)
12>     REFERENCES customer_location (cust_id, cust_loc)
13> )
14> GO
1>
2> drop table orders;
3> GO
1>
2> drop table customer_location;
3> GO
1>
2> drop table master_customer;
3> GO</source>
    
   

== REFERENCES customer(cust_id) (from another table)==



   
  <!-- start source code -->
   
    <source lang="sql">
3> CREATE TABLE customer
4> (
5> cust_id      int            NOT NULL  IDENTITY  PRIMARY KEY,
6> cust_name    varchar(50)    NOT NULL
7> )
8> GO
1>
2> CREATE TABLE orders
3> (
4> order_id    int        NOT NULL  IDENTITY  PRIMARY KEY,
5> cust_id     int        NOT NULL  REFERENCES customer(cust_id)
6> )
7> GO
1></source>
    
   

== Self-Referencing Tables==



   
  <!-- start source code -->
   
    <source lang="sql">
4> CREATE TABLE employee
5> (
6> emp_id      int            NOT NULL PRIMARY KEY,
7> emp_name    varchar(30)    NOT NULL,
8> mgr_id      int            NOT NULL REFERENCES employee(emp_id)
9> )
10> GO
1>
2> INSERT employee VALUES (1, "Chris Smith", 1)
3> GO
(1 rows affected)
1>
2>
3> drop table employee;
4> GO</source>