5.CHECK约束 --CheckALTERTABLEdbo.EmployeesADDCONSTRAINTCHK_Employees_salaryCHECK(salary>0.00); 6.默认约束 --DefaultALTERTABLEdbo.OrdersADDCONSTRAINTDFT_Orders_ordertsDEFAULT(SYSDATETIME())FORorderts;--CleanupDROPTABLEdbo.Orders, dbo.Employees;
alter table 表名 add constraint 约束名 check (字段 between 1 and 100 ) ---添加外键约束(主表stuInfo和从表stuMarks建立关系,关联字段为stuNo) alter table 从表 add constraint 约束名 foreign key(关联字段) references 主表(关联字段) --sql server中删除约束的语句是: alter table 表名 drop constrai...
ADD CONSTRAINT CK_Gender CHECK (Gender = 0 OR Gender = 1), ADD CONSTRAINT DF_Gender DEFAULT (0) FOR Gender; ``` 为`OrderInfo` 表添加外键约束和默认值约束: ```sql ALTER TABLE OrderInfo ADD CONSTRAINT FK_Userld FOREIGN KEY (Userld) REFERENCES UserInfo (Userld), ADD CONSTRAINT FK_Commodit...
Satu-satunya cara yang dapat diandalkan untuk menemukan skema objek adalah dengan mengkueri sys.objects tampilan katalog. CONSTRAINT_NAME nama sysname Nama batasan. CHECK_CLAUSE nvarchar(4000) Teks aktual dari pernyataan definisi Transact-SQL.
通过T-SQL语句修改表约束,在表employee加入CHECK约束:输入的员工编号必须以E开头的5位数编号,性别只能为M/F。(4分)A. LTER TABLE employee ADD CONSTRAINT c1 CHECK(emp_no LIKE ('E[0-9][0-9][0-9][0-9]'))B. LTER TABLE employee ADD CONSTRAINT c2 CHECK(sex IN (‘M’,’F’)) 相关知识点...
When you create a primary key, SQL Server enforces the constraint behind the scenes by creating a unique index on that column and using the primary key column or columns as the keys of the index. 当你创建一个主键时,SQL Server强制在幕后对这个列创建唯一性索引,并使用主键列作为索引的键。
Subclause 11.9, "<check constraint definition>": <check constraint definition> ::= CHECK <left paren> <search condition> <right paren> ... Conformance Rules Without Feature F672, "Retrospective check constraints", conforming SQL language shall not contain a <check constraint definition> that ...
(primary key constraint):要求主键列数据唯一,并且不允许为空 唯一约束(unique constraint):要求该列唯一,允许为空,但只能出现一个空值 检查约束(check constraint):某列取值范围、格式限制等,如有关年龄的约束 默认约束(default constraint):某列的默认值 外键约束(foregin key constraint):用于两表间建立关系,...
SQL Server Azure SQL 数据库 Azure SQL 托管实例 检查当前数据库中指定表上的指定约束或所有约束的完整性。 Transact-SQL 语法约定 语法 syntaxsql DBCCCHECKCONSTRAINTS[ (table_name|table_id|constraint_name|constraint_id) ] [WITH[ {ALL_CONSTRAINTS|ALL_ERRORMSGS} ] [ , ] [NO...
2.1.2.77 F492, Optional table constraint enforcement 2.1.2.78 F502, Enhanced documentation tables 2.1.2.79 F502-01, SQL_SIZING_PROFILES view 2.1.2.80 F502-02, SQL_IMPLEMENTATION_INFO view 2.1.2.81 F502-03, SQL_PACKAGES view 2.1.2.82 F521, Assertions 2.1.2.83 F531, Temporary tables 2.1.2.8...