How to set primary key in oracle?

How to set the primary key in oracle: 1. Define the primary key when creating the table, the code is [constraint TF_B_AIR_CONFIG_PK primary key (TYPE_ID)]; 2. After creating the table, use alter table syntax to set the primary key.

How to set the primary key in oracle:

1. What is the primary key

Primary key (primary key) is one or more fields in the table, and its value is used to uniquely identify a record in the table.

The so-called composite primary key means that the primary key of your table contains more than one field. If there is no unique primary key in the table, you can use a composite primary key to determine the uniqueness of a record.

2. Two ways to create a primary key

The first is to define the primary key when creating the table

Example of single-column primary key :

----创建TF_B_AIR_CONFIG表
create table ECS_STORE.TF_B_AIR_CONFIG(
  TYPE_ID            VARCHAR2(20) not null,
  PROVINCE_CODE      VARCHAR2(4) not null,
  PARAMETER_TYPE     VARCHAR2(2) not null,
  LIMIT_NUM          VARCHAR2(4) not null,
  EFFECTIVE_FALG     VARCHAR2(2) default '1',
  UPDATE_TIME        DATE default sysdate,
  constraint TF_B_AIR_CONFIG_PK primary key(TYPE_ID)--单列主键  
)

Example of composite primary key:

----创建TF_B_AIR_CONFIG表
create table ECS_STORE.TF_B_AIR_CONFIG(
  TYPE_ID            VARCHAR2(20) not null,
  PROVINCE_CODE      VARCHAR2(4) not null,
  PARAMETER_TYPE     VARCHAR2(2) not null,
  LIMIT_NUM          VARCHAR2(4) not null,
  EFFECTIVE_FALG     VARCHAR2(2) default '1',
  UPDATE_TIME        DATE default sysdate,
  constraint TF_B_AIR_CONFIG_PK primary key(TYPE_ID , PROVINCE_CODE)--复合主键  
)

Second, after creating the table, use alter table syntax

Syntax

ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (col1, col2,...coln);

Example

----创建TF_B_AIR_CONFIG表
create table ECS_STORE.TF_B_AIR_CONFIG(
  TYPE_ID            VARCHAR2(20) not null,
  PROVINCE_CODE      VARCHAR2(4) not null,
  PARAMETER_TYPE     VARCHAR2(2) not null,
  LIMIT_NUM          VARCHAR2(4) not null,
  EFFECTIVE_FALG     VARCHAR2(2) default '1',
  UPDATE_TIME        DATE default sysdate
)

rrree

Related learning recommendations: oracle database learning tutorial

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