CREATE TABLE table_name ( column1 INT PRIMARY KEY, column2 VARCHAR(50) ); 复制代码 在已创建的表中,使用ALTER TABLE语句来添加PRIMARY KEY约束。例如: ALTER TABLE table_name ADD PRIMARY KEY (column1); 复制代码 在创建表时,使用PRIMARY KEY关键字来定义主键列。例如: CREATE TABLE table_name ( ...
Before you can remove a primary key, you must make sure that it doesn't participate in any table relationships. If you try to remove a primary key that is part of one or more relationships, Access warns you that you must delete the relationships first. ...
Create a query, form, or report Learn more Intro to Access Create an Access database Add tables Use relationships Add and edit data Manage data with queries Create forms Create reports Create charts Protect databases Add a primary key to a table in AccessAdd...
CREATE TABLE user( id INT PRIMARY KEY NOT NULL, name VARCHAR(16) NOT NULL, UNIQUE unique_name (name(10)) ); 1. 2. 3. 4. 5. (2)也可以在表创建后创建,如下sql: CREATE UNIQUE INDEX unique_name ON user(name(10)); 1. (3)通过修改表结构创建,如下sql: ALTER user ADD UNIQUE unique_...
You know how to create a table from a make-table query, but when you create a table in this way it has no primary key or any other indexes. Furthermore, you can only create a new table with a structure based on that of an existing table. You’d like a way to create a table on...
show index from tableName; 1. 唯一索引: 建表时创建唯一索引: create table person(id int not null primary key auto_increment,name char(10) not null,age int not null,address varchar(100) not null,unique index_name(name)); 1. 创建唯一索引: ...
On the File menu, click Close, and then click No to close the Make-Table Query window. Click Tables on the left pane, right-click the new table, and then click Design View. In the Design view for the table, add an AutoNumber field that has the same field name that you deleted in ...
RetrieveMultipleEvent: False GET /principalobjectattributeaccesssetSee Query data Query data UpdateEvent: True PATCH /principalobjectattributeaccessset(principalobjectattributeaccessid)See Update Update records UpsertEvent: False PATCH /principalobjectattributeaccessset(principalobjectattributeaccessid)See...
37、若数据库中有表STUD,则下列函数实现的功能是FunctionDropPrimaryKey()DimstrSQLAsStringstrSQL="ALTERTABLESTUDDropCONSTRAINTPRIMARY_KEY"CurrentProject.Connection.ExecutestrSQLEndFunctionA、为关系STUD中设置主关键字B、取消关系STUD中的主关键字C>为关系STUD添加索引...
Office Excel Primary Interop Assembly 搜尋 Microsoft.Office.Interop.Excel _Application _Chart _Global _IOLEObject _IQueryTable _OLEObject _QueryTable _Workbook _Worksheet AboveAverage Action Actions AddIn AddIns AddIns2 Adjustments AllowEditRange AllowEditRanges AppEvents AppEvents_AfterCalculateEvent...