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 ...
Get error at ExecuteNonQuery() during INSERT data into table Get identity after insert using default using Text Sql Commands Get max value with linq query Get sql server return value in asp.net get the databasename from web.config Get the last inserted row's Identity (ID) using DataTable a...
Constraintsplace limitations on the data that can be entered into a column or columns. A primary key enforces entity integrity, meaning that rows are guaranteed to be unambiguous and unique. Best practices for database normalization dictate that every table should have a primary key. A primary k...
添加有名称的主键约束:alter table table_name add constraint pk_name primary key (id); 删除有名称的主键约束:alter table table_name drop constraint pk_name; 6.修改表字段类型 例子:alter table student alter column birthday decimal(18, 4) not null 三、简单的sql语句(增删改查) 1.插入(insert) 向...
insert into 表名称 values (值1,值2,...) insert into table_name (列1,列2,...) values (值1,值2,...) INSERT INTO 语句用于向一张表中插入新的行。 SELECT INTO 语句从一张表中选取数据插入到另一张表中。常用于创建表的备份复件或者用于对记录进行存档。
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] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
--创建订单表CREATETABLEorders(order_idINTPRIMARYKEY,customer_idINT,order_dateDATE,total_amountDECIMAL(10,2));--创建产品表CREATETABLEproducts(product_idINTPRIMARYKEY,product_nameVARCHAR(255),unit_priceDECIMAL(10,2));--创建客户表CREATETABLEcustomers(customer_idINTPRIMARYKEY,customer_nameVARCHAR(255),...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...