In SQL Server, all table constraints are database objects, just like tables, views, stored procedures, functions, and so on. Therefore, constraints must have unique names across the database. But because every table constraint is scoped to an individual table, it makes sense to adopt a naming...
FILENAME=‘c:\Program Files\Microsoft SQL Server\MSSQL.1\mssql\data\AccountingLog.ldf’, SIZE=5MB, MAXSIZE=25MB, FILEGROWTH=5MB) GO 查看数据库的信息,使用以下语句执行: exec sp_helpdb ‘Accounting’ 2.创建表 创建表,其命令语法格式如下: CREATETABLE[database_name.[owner].]table_name ( <col...
Using ALTER TABLEand ADD CONSTRAINT, you can add aforeign key to an existing table. The syntax for doing so is as follows: ALTERTABLEtable_nameADDCONSTRAINTconstraint_nameFOREIGNKEY(column_name)REFERENCES[ schema_name.] referenced_table_name [ ( ref_column ) ] This example adds aforeign key ...
Exercise 1 Use ALTER TABLE to ADD and Modify Columns 练习一:使用ALTER TABLE来添加和修改列 Examine the following CREATE TABLE statement, from the TSQL2012.sql script, that is used to create the Production.Categories table. 从TSQL2012.sql脚本开始,测试下面的CREATE TABLE语句,它是用来创建一个Produc...
1、使用sql查询主键的唯一约束当前最大值：select max（id） from table；（id为number类型）select max（to_number(id)） from table;(id为非number类型)2、使用sql查询该表的序列的下一个值 select SEQ.NEXTVAL from dual;（seq是对应表的序列名）3、最后使用PL/SQL客户端编辑序列，将序列的下一...
SQL Server引擎从对应的行查找SalesDate和SalesPersonID列的值。 在上面的步骤中,对ProductID = 112的每个主键记录(这里是400),SQL Server引擎要搜索400次聚集索引树以检索查询中指定的其它列(SalesDate,SalesPersonID)。 如果非聚集索引页中包括了聚集索引键和其它两列(SalesDate,,SalesPersonID)的值,SQL Server引擎...
stuID numeric(18,0) unique --身份证 ) --- 添加约束 --- -- 主键约束:PK_字段名 alter table stuInfo add constraint PK_stuNo primary key(stuNo); -- 唯一约束:UQ_字段名 alter table stuInfo add constraint UQ_stuNo unique(stuID);
允许的约束类型仅为 PRIMARY KEY、UNIQUE KEY 和 NULL。 有关语法的详细信息,请参阅 CREATE TABLE (Transact-SQL) 、CREATE FUNCTION (Transact-SQL) 和DECLARE @local_variable (Transact-SQL)。 collation_definition 由Microsoft Windows 区域设置和比较样式、Windows 区域设置和二进制表示法或 Microsoft SQL Server...
ExplicitVisit 方法 (TSqlStatement) ExplicitVisit 方法 (UnaryExpression) ExplicitVisit 方法 (UniqueConstraint) ExplicitVisit 方法 (UnpivotedTableSource) ExplicitVisit 方法 (UnqualifiedJoin) ExplicitVisit 方法 (UpdateCall) ExplicitVisit 方法 (UpdateForClause) ExplicitVisit 方法 (UpdateMergeAction) ExplicitVisit...
The problem to be solved was the following: Given this table: Copy CREATE TABLE Enrollments ( StudentId INT NOT NULL ,Enroll_Date DATE NOT NULL ,Class VARCHAR(30) NOT NULL ) ALTER TABLE Enrollments ADD CONSTRAINT PK_Enrollments_StudentID_Enroll_Date PRIMARY KEY ( StudentId ,Enroll_Date ...