Oracle PL/SQL:CREATE TABLE statement: create a table with primary key.CREATE TABLE statement can be used to create table objects in database. It is possible to add constraints like primary key ,foreign key while table creation.Primary key is the unique identifier for a row of data.One ...
In this recipe, I’ll demonstrate how to add aprimary key to an existing table using ALTER TABLEand ADDCONSTRAINT:ALTERTABLEPerson.EducationTypeADDCONSTRAINTPK_EducationTypePRIMARYKEY(EducationTypeID) 1.3:Creating aTable with aForeign Key Reference In this recipe, I’ll demonstrate how to create a...
createtime timestamp, primary key(id), t_id int FOREIGN KEY REFERENCES teacher(t_id) //一个外键 ); <!--可建立联合主键,例如primary key(id,name),这样id和name都是主键,且id不允许重复,name也不允许重复。--> 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 给表添加主键、外键: <!-...
你写上去的编译的时候有点小错误,正确的应该是这样写的 Create table [dbo].[adminitable]([adminpassword] [varchar](50) null,[adminname] [varchar](20) null,constraint [pk_adminitable] primary key clustered ([adminname] asc )with (pad_index=off,statistics_norecompute=off,ignore_d...
CREATE TABLE customers ( customer_id int PRIMARY KEY, customer_name varchar(50) NOT NULL, customer_email varchar(100) UNIQUE ); 在这个例子中,我们为"customer_id"列添加了一个主键约束,表示它是表的主键。主键约束将确保该列的值唯一且非空。我们还为"customer_name"列添加了一个非空约束,以确保它不...
简介:【7月更文挑战第24天】CREATE TABLE 时的 SQL PRIMARY KEY 约束。 CREATE TABLE 时的 SQL PRIMARY KEY 约束 下面的 SQL 在 "Persons" 表创建时在 "P_Id" 列上创建 PRIMARY KEY 约束: MySQL: CREATE TABLE Persons ( P_Id int NOT NULL, ...
第十四章 SQL命令 CREATE TABLE(一) 创建表 大纲 CREATE [GLOBAL TEMPORARY] TABLE table (table-element-commalist) [shard-key] [WITH table-option-commalist] table-element ::= [%DESCRIPTION string] [%FILE string] [{%EXTENTSIZE | %NUMROWS} integer] ...
PRIMARYKEY(id) ); In Oracle and SQL Server CREATETABLECompanies (idintNOTNULLPRIMARYKEY,namevarchar(50), addresstext, emailvarchar(50), phonevarchar(10) ); Define constraints while creating a table We can also add different types of constraints while creating a table. For example, ...
CREATE TABLE `tb001` ( `ID` int(11) NOT NULL AUTO_INCREMENT, `C1` int(11) DEFAULT NULL, PRIMARY KEY (`ID`) ) ENGINE=InnoDB AUTO_INCREMENT=6684558 DEFAULT CHARSET=utf8; CREATE TABLE `tb002` ( `ID` int(11) NOT NULL AUTO_INCREMENT, ...
CREATE TABLE- 创建新表 ALTER TABLE- 变更(改变)数据库表 DROP TABLE- 删除表 CREATE INDEX- 创建索引(搜索键) DROP INDEX- 删除索引 (2)数据操纵(SQL DML)数据操纵分成数据查询和数据更新两类。数据更新又分成插入、删除、和修改三种操作。 (3)数据控制(DCL)包括对基本表和视图的授权,完整性规则的描述,事务...