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 your d
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, DOB DATETIME, Dept varchar(...
Note that the above code works in all major database systems. However, some databases may have a different syntax. SQL PRIMARY KEY Syntax The syntax of the SQLPRIMARY KEYconstraint is: CREATETABLEtable_name ( column1 data_type, ..., [CONSTRAINTconstraint_name] PRIMARYKEY(column1) ); Here,...
如果控制碼上的上一個函式呼叫傳回SQL_STILL_EXECUTING且啟用通知模式, 則必須在控制碼上呼叫 SQLCompleteAsync ,才能執行後續處理並完成作業。 註解 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。
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 ...
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: ...
Syntax: CREATE TABLE column1 data_type[(size)] NOT NULL PRIMARY KEY, column2 data_type[(size)], ...); Parameters: Good practice for primary keys in tables Primary keys should be as small as necessary. Prefer a numeric type because numeric types are stored in a much more compact forma...
Primary Key Syntax A primary key is defined during table creation. Let’s look at the basic syntax for defining a primary key in SQL. CREATETABLEProduct ( ProductIdINTPRIMARYKEY, ProductNameVARCHAR(50), QuantityInStockINT ); TheProductIdcolumn is the primary key of theProducttable. It is ...
Primary key syntax We've already seen several examples of thePRIMARY KEYclause of theCREATE TABLEstatement. It looks like this: CREATETABLEcities(cityvarchar(255),state_idvarchar(2),zip_codevarchar(5),PRIMARYKEY(city,state_id)); After defining columns, you add aPRIMARY KEYclause with the col...
In this syntax: First, specify the name of the table from which you want to remove the primary key. Second, provide the primary key constraint to drop. Let’s take an example of removing the primary key constraint from the vendors table using psql. First, display the structure of the ven...