https://dev.mysql.com/doc/refman/8.0/en/create-table-check-constraints.html Quote A column constraint appears within a column definition and can refer only to that column. The CHECK for tolerance can only refer to tolerance column. Where is pct defined?
SQL_ISV_CONSTRAINT_TABLE_USAGE = 标识约束(引用、唯一和断言)使用的表,并且由给定用户拥有。 (中级)SQL_ISV_DOMAIN_CONSTRAINTS = 标识可由给定用户访问的域约束(目录中的域)。 (中级)SQL_ISV_DOMAINS = 标识用户可以访问的目录中定义的域。 (中级)SQL_ISV_KEY_COLUMN_USAGE = 标识目录中定义的列,这些列...
sys.key_constraintsfor key constraints (e.g. primary keys) sys.foreign_keysfor foreign key relations and alot more- check it out! You can query and join those views to get the info needed - e.g. this will list the tables, columns and all default constraints defined on them: SELECT Ta...
MySQL使用information_schema数据库里的TABLE_CONSTRAINTS表来保存该数据库的实例中的所有约束信息,用户可以通过查询TABLE_CONSTRAINTS表来获取该数据库的约束信息。 4.1 NOT NULL约束 非空约束用于确保指定列不允许为空,非空约束是比较特殊的约束,它只能作为列级约束使用,只能使用列级约束语法定义。 SQL中null不区分大小...
CHECK_CONSTRAINTS COLUMN_DOMAIN_USAGE COLUMN_PRIVILEGES COLUMNS CONSTRAINT_COLUMN_USAGE CONSTRAINT_TABLE_USAGE DOMAIN_CONSTRAINTS DOMAINS KEY_COLUMN_USAGE PARAMETERS REFERENTIAL_CONSTRAINTS ROUTINE_COLUMNS ROUTINES SCHEMATA SEQUENCES TABLE_CONSTRAINTS TABLE_PRIVILEGES ...
Query below lists all table (and view) constraints - primary keys, unique key constraints and indexes, foreign keys and check and default constraints. Query selecttable_view, object_type, constraint_type, constraint_name, detailsfrom(selectschema_name(t.schema_id) +'.'+ t.[name]astable_view...
To query existing check constraints, use the sys.check_constraints system catalog view. Permissions Requires ALTER permissions on the table. Use SQL Server Management Studio In Object Explorer, expand the table to which you want to add a check constraint, right-click Constraints and select New Con...
To list the primary key constraints in a database, you can query the sys.key_constraints table filtering on a type of PK. 为了在数据库中列出主键索引,你可以查询sys.key_constraints表,并用type='PK'作为筛选。 SQLSELECT * FROM sys.key_constraints ...
table 存储结果集,供稍后处理。 约束(Constraints) 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)。 NOT NULL 约束 强制字段始终包含值,不接受 NULL 值,如果不向字段添加值,就无法插入新记录或者更新记录。
Specifies the order in which the column or columns participating in table constraints are sorted. The default is ASC. WITH FILLFACTOR=fillfactor Specifies how full the Database Engine should make each index page used to store the index data. User-specifiedfillfactorvalues can be from 1 through 10...