UNIQUE PRIMARY KEY FOREIGN KEY IS_DEFERRABLE varchar(2) 指定限制检查是否可延迟。始终返回 NO。 INITIALLY_DEFERRED varchar(2) 指定是否首先延迟约束检查。始终返回 NO。 参考 其他资源 查询SQL Server 系统目录 帮助和信息 获取SQL Server 2005 帮助
DOMAIN_CONSTRAINTS DOMAINS KEY_COLUMN_USAGE PARAMETERS REFERENTIAL_CONSTRAINTS ROUTINE_COLUMNS ROUTINES SCHEMATA TABLE_CONSTRAINTS TABLE_PRIVILEGES TABLES VIEW_COLUMN_USAGE VIEW_TABLE_USAGE VIEWS Procédures stockées système Tables système Informations de référence sur Transact-SQL (T-SQL...
Applies to: SQL Server 2008 (10.0.x) and later. Can be specified for FOREIGN KEY constraints and CHECK constraints. If this clause is specified for a constraint, the constraint is not enforced when replication agents perform insert, update, or delete operations. ...
上面都是通过information_schema数据库中的table_constraints表来查询所有的约束信息。对于外键的约束的命名,还可以通过表referential_constraints来查看比较详细的外键属性,如: select * from information_schema.referential_constraints where constraint_schema='demo'\G; 三、约束和索引的区别 我们可以使用create unique in...
SQL 约束 约束用于限制加入表的数据的类型。 可以在创建表时规定约束(通过 CREATE TABLE 语句),或者在表创建之后也可以(通过 ALTER TABLE 语句)。 我们将主要探讨以下几种约束: NOT NULL UNIQUE PRIMARY KEY FOREIGN KEY CHECK DEFAULT SQL NOT NULL 约束 ...
兼容性视图 (Transact-SQL) 数据层应用程序视图 (Transact-SQL) 动态管理视图和函数 (Transact-SQL) 信息架构视图 (Transact-SQL) 信息架构视图 (Transact-SQL) CHECK_CONSTRAINTS (Transact-SQL) COLUMN_DOMAIN_USAGE (Transact-SQL) COLUMN_PRIVILEGES (Transact-SQL) ...
greenZ DB2 SQL:table,comment,constraints 1.table 1.1 创建 非分区表 1.2 字段:添加字段,删除字段,修改字段数据类型长度,更改字段名 1.3 更改表名,复制表结构(约束除外) 2.comment 2.1 comment on table 2.2 comment on column 3.constrains 3.1添加约束:default ,null|not null,primary key,uique,foreign ...
For more information, see SET QUOTED_IDENTIFIER (Transact-SQL). FOREIGN KEY REFERENCES Is a constraint that provides referential integrity for the data in the column. FOREIGN KEY constraints require that each value in the column exist in the specified column in the referenced table. referenced_...
and an error is returned. When a new PRIMARY KEY or UNIQUE constraint is added to an existing column, the data in the column or columns must be unique. If duplicate values are found, ALTER TABLE fails. The WITH NOCHECK option has no effect when PRIMARY KEY or UNIQUE constraints are ...
TheTABLE_CONSTRAINTStable describes which tables have constraints. TheTABLE_CONSTRAINTStable has these columns: CONSTRAINT_CATALOG The name of the catalog to which the constraint belongs. This value is alwaysdef. CONSTRAINT_SCHEMA The name of the schema (database) to which the constraint belongs. ...