The primary key creates aCLUSTEREDindex on the column(s) by default in many databases. The specific syntax for working with primary keys may vary slightly depending on the SQL dialect you're using (such as MySQL, PostgreSQL, SQL Server, etc.), so always check the specific documentation for ...
FOREIGN KEY (PersonID) REFERENCES Persons(PersonID) ); 在多个列上建立外键: To allow naming of a FOREIGN KEYconstraint, and for defining a FOREIGN KEY constraint on multiple columns, use the following SQLsyntax: MySQL / SQL Server / Oracle / MS Access: CREATE TABLE Orders ( OrderID int NO...
这个错误通常出现在SQL语句中,尤其是在尝试创建或修改数据库表时。错误提示表明SQL解析器在解析到“primary”关键字附近时遇到了问题。 2. 检查与"primary"相关的SQL语句 在SQL中,“primary”关键字通常用于定义主键(PRIMARY KEY)。主键是用来唯一标识表中每一行的列或列的组合。 3. 识别并指出SQL语句中的语法错误...
SQLPrimaryKeys 會以標準結果集的形式傳回結果,依TABLE_CAT、TABLE_SCHEM、TABLE_NAME和KEY_SEQ排序。 如需如何使用這項資訊的資訊,請參閱 目錄資料的 使用方式。 下列資料行已針對 ODBC 3 重新命名。 x . 資料行名稱變更不會影響回溯相容性,因為應用程式會依資料行編號系結。 展開資料表 ODBC 2.0 資料行ODB...
SQL PRIMARY KEY Syntax The syntax of the SQLPRIMARY KEYconstraint is: CREATETABLEtable_name ( column1 data_type, ..., [CONSTRAINTconstraint_name] PRIMARYKEY(column1) ); Here, table_nameis the name of the table to be created column1is the name of the column where thePRIMARY KEYconstraint...
SQL Server / Oracle / MS Access: CREATETABLEPersons ( ID intNOTNULLPRIMARYKEY, LastName varchar(255)NOTNULL, FirstName varchar(255), Age int ); To allow naming of aPRIMARY KEYconstraint, and for defining aPRIMARY KEYconstraint on multiple columns, use the following SQL syntax: ...
To create the Primary Key in SQL on a table with the user-defined Primary Key namePK_Employees, use the below syntax: CREATE TABLE HumanResources.Employees ( Employee_Id INT IDENTITY NOT NULL, First_Name VARCHAR(100) NOT NULL, Last_Name VARCHAR(100) NOT NULL, ...
KEY_SEQ (ODBC 1.0)5Smallint(非 NULL)键 (中的列序列号从 1) 开始。 PK_NAME (ODBC 2.0)6Varchar主键名称。 如果不适用于数据源,则为 NULL。 代码示例 请参阅SQLForeignKeys。 相关函数 ODBC API 参考 ODBC 头文件 其他资源 活动 加入AI 技能节挑战 ...
A primary key is a way to identify exactly one record in a SQL table. Every row in that table will have a different primary key that uniquely identifies it and no other row. This is easiest to see with an example. First, we'll make a table without a primary key. Here's an example...
Technically, a primary key constraint is the combination of a not-null constraint and a UNIQUE constraint. Typically, you define primary for a table when creating it: CREATE TABLE table_name ( column_1 data_type PRIMARY KEY, column_2 data_type, … ); In this syntax, you define the prima...