public bool IsPrimaryKey { get; } 属性值 Boolean 如果约束在主键上,则为 true;否则为 false。 示例 以下示例检查 属性 IsPrimaryKey。 VB 复制 Private Sub GetPrimaryKey() Dim dataRelation As DataRelation Dim uniqueConstraint As UniqueConstraint ' Get a DataRelation from a DataSet. ...
public bool IsPrimaryKey { get; set; } 属性值类型:System.Boolean.NET Framework 安全性对直接调用方的完全信任。此成员不能由部分信任的代码使用。有关更多信息,请参见通过部分受信任的代码使用库。请参见参考UniqueConstraint 类Microsoft.Data.Schema.ScriptDom.Sql 命名空间中文...
public static bool GetIsPrimaryKey (this Microsoft.EntityFrameworkCore.Metadata.IUniqueConstraint uniqueConstraint); 参数 uniqueConstraint IUniqueConstraint 元数据项。 返回 Boolean true 如果约束是主键,则为 适用于 产品版本 Entity Framework Core 5.0 在...
unique_checks=0时导致,在bug(106121)列表中官方解释的原因:该参数关闭,维护唯一索引时,不会进行物理读,只会进行内存读,来确保唯一索引的唯一性,即如果内存中有冲突数据就报1062,如果内存中没有冲突数据插入成功,不会进行io来将唯一索引相关的数据页拉取到内存。 官方的回复“IMHO this is not a bug”,我理解...
Represents if the constraint is not just unique but also primary key. C# 複製 public bool IsPrimaryKey { get; set; } Property Value Boolean Applies to 產品版本 Microsoft.SQLServer.DacFx 140.3881.1, 150.18208.0, 160.2004021.0, 161.6374.0, 161 ...
The only unique constraint onTABLE1is defined oncol1through a primary key constraint. Assume that you have one record (1,1,'Dallas'). When you execute this code: SQL UPDATETABLE1setcol1 =3wherecol3 ='Dallas' TheUPDATEstatement is implemented by SQL Server as a pair ofDELETE/INSERTsta...
The only unique constraint onTABLE1is defined oncol1through a primary key constraint. Assume that you have one record (1,1,'Dallas'). When you execute this code: SQL UPDATETABLE1setcol1 =3wherecol3 ='Dallas' TheUPDATEstatement is implemented by SQL Server as a pair of...
Physical Role: The primary key is a specific implementation of the entity identifier when the database is created. It is a physical constraint defined in the database schema. Purpose: The primary key ensures that each row in a database table is unique and enforces the integrity of the data...
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A primary key constraint from a table was dropped and tried to be recreated but the error below occurred:ORA-00955: name is already used by an existing objectFor example:ALTER TABLE < table name> ADD CONSTRAINT <new_constraint> PRIMARY KEY (instance_id,ais_user,server,port)Checking all_...