constraint fk_girl foreign key boy_gril(girl_id) references girl(id) )default charset=utf8; -- 创建表之后添加外键 alter table boy_girl add constraint fk_boy foreign key boy_girl(boy_id) references boy(id); alter table boy_girl add constraint fk_girl foreign key boy_girl(girl_id) refer...
You can create a unique constraint in SQL Server by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that don't participate in a primary key. Crea
[インデックス/キー] ダイアログ ボックスの [Selected Primary/Unique Key and Index (選択された主/一意キーまたはインデックス)] ボックスの一意キーをクリックします。 [Delete] をクリックします。 [ファイル] メニューの [<テーブル名> を保存] をクリックします。Transact...
However, you can have manyUNIQUEconstraints per table, but only onePRIMARY KEYconstraint per table. SQL UNIQUE Constraint on CREATE TABLE The following SQL creates aUNIQUEconstraint on the "ID" column when the "Persons" table is created: ...
- There can be only one primary key on a table wherein a table can have multiple unique key defined on it. Let’s create a table with a primary key and a unique key constraint. Transact-SQL 1 2 3 4 5 6 7 8 9 10 11 CREATETABLEtblCns (snoINTNOTNULL, col1VARCHAR(100),col2VARC...
附錄H:Analysis of the Unique Particle Attribution Constraint (non-normative) (唯一物件屬性條件約束的分析 (非標準)) 若要查看文件,請瀏覽 http://www.w3.org/TR/xmlschema-1。 另請參閱 XML 結構描述集合 (SQL Server) 其他資源 事件 加入AI 技能節挑戰 4月8日 下午11時 - 5月28日 下午3時 ...
AlterServiceMasterKeyStatement AlterServiceStatement AlterSymmetricKeyStatement AlterTableAddTableElementStatement AlterTableAlterColumnOption AlterTableAlterColumnStatement AlterTableAlterIndexStatement AlterTableAlterPartitionStatement AlterTableChangeTrackingModificationStatement AlterTableConstr...
uniquekey constraint requires that every value in a column or set of columns beunique. No rows of a table may have duplicate values in a column (the uniquekey) or set of columns (the composite unique key) with a unique key constraint. ...
Constraints are rules that the SQL Server Database Engine enforces for you. For example, you can useUNIQUEconstraints to make sure that no duplicate values are entered in specific columns that don't participate in a primary key. Although both aUNIQUEconstraint and aPRIMARY KEYconstraint enforce ...
uniquekey constraint requires that every value in a column or set of columns beunique. No rows of a table may have duplicate values in a column (the uniquekey) or set of columns (the composite unique key) with a unique key constraint. ...