The below given example uses CREATE TABLE statement to create a table with a single column primary key.1 2 3 4 5 6 7 SQL> create table MYTABLE( name VARCHAR2(50), id NUMBER, salary NUMBER(8,2), CONSTRAINT MYTABLE_ID PRIMARY KEY (id));...
For instance, type the below command to create a new table named “Workers” with the PRIMARY KEY CONSTRAINT name and click on the “Execute” button: CREATE TABLE Workers ( worker_id NUMBER, worker_name VARCHAR2(30), worker_phone NUMBER (20), worker_mail VARCHAR2(50), CONSTRAINT pk_...
为 的主键约束 CreateTableOperation生成SQL 片段。 C# 复制 protected virtual void CreateTablePrimaryKeyConstraint (Microsoft.EntityFrameworkCore.Migrations.Operations.CreateTableOperation operation, Microsoft.EntityFrameworkCore.Metadata.IModel? model, Microsoft.EntityFrameworkCore.Migrations...
{ CASCADE | NO ACTION } ] } < table_constraint > ::= [ CONSTRAINT constraint_name ] { [ { PRIMARY KEY | UNIQUE } { ( column [ ,...n ] ) } ] | FOREIGN KEY ( column [ ,...n ] ) REFERENCES ref_table [ ( ref_column [ ,...n ] ) ] [ ON DELETE { CASCADE | NO ...
SQL PRIMARY KEY 约束 PRIMARY KEY 约束唯一标识数据库表中的每条记录。 主键必须包含唯一的值。 主键列不能包含 NULL 值。 每个表应该都一个主键,并且每个表只能有一个主键。 SQL PRIMARY KEY Constraint on CREATE TABLE 下面的 SQL 在 "Persons" 表创建时在 "Id_P" 列创建 PRIMARY KEY 约束: ...
PRIMARY KEY index_parameters | REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE referential_action ] [ ON UPDATE referential_action ] } [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] table_constraint 是: [ ...
[ CONSTRAINT constraint_name ] { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ , ...n ] ) ] | [ FOREIGN KEY ] REFERENCES referenced_table_name [ ( ref_column ) ] [ ON DELETE { NO ACTION | CASCADE } ] [ ON ...
obclient>CREATETABLEtbl8(col1INT,col2INT,col3INT,CONSTRAINTequal_check1CHECK(col2=col3*2)ENABLEVALIDATE);Query OK,0rowsaffected 为表ref_t2指定外键,当DELETE操作影响与子表相匹配行的父表中键值时,执行SET NULL操作。 obclient>CREATE TABLE ref_t1(c1 INT PRIMARY KEY,C2 INT);Query OK,0rows aff...
obclient>CREATETABLEtbl8(col1INT,col2INT,col3INT,CONSTRAINTequal_check1CHECK(col2=col3*2)ENABLEVALIDATE);Query OK,0rowsaffected 为表ref_t2指定外键,当DELETE操作影响与子表相匹配行的父表中键值时,执行SET NULL操作。 obclient>CREATE TABLE ref_t1(c1 INT PRIMARY KEY,C2 INT);Query OK,0rows aff...
其中表约束table_constraint为: [ CONSTRAINT constraint_name ] { CHECK ( expression ) | UNIQUE ( column_name [, ... ] ) index_parameters | PRIMARY KEY ( column_name [, ... ] ) index_parameters | PARTIAL CLUSTER KEY ( column_name [, ... ] ) } [ DEFERRABLE | NOT DEFERRABLE | ...