3. Enable novalidate state. 4. Enable state. Some benefits of using constraints in this order are: ■ No locks are held. ■ All constraints can go to enable state concurrently. ■ Constraint enabling is done in parallel. ■ Concurrent activity on table is permitted. 大意就是指好处有: 不会...
To enable a UNIQUE or PRIMARY KEY constraint, you must have the privileges necessary to create an index on the table. You need these privileges because Oracle creates an index on the columns of the unique or primary key in the schema containing the table. To enable or disable triggers, ...
不支持 immutable_table_clauses 子句修改不可变表的定义,会报错。 不支持 blockchain_table_clauses 子句修改区块链表的定义,会报错。 不支持 memoptimize_read_clause 子句提高高频数据查询操作的性能,会报错。 不支持 memoptimize_write_clause 子句启用快速写入,会报错。 不支持 enable_disable_clause 子句定义数据...
] [ ENABLE_SCHEMA_EVOLUTION = { TRUE | FALSE } ] [ COMMENT = '<string_literal>' ] ALTER TABLE [ IF EXISTS ] <name> UNSET { DATA_RETENTION_TIME_IN_DAYS | MAX_DATA_EXTENSION_TIME_IN_DAYS | CHANGE_TRACKING | DEFAULT_DDL_COLLATION | ENABLE_SCHEMA_EVOLUTION | COMMENT | } [ , ......
constraint_clause Purpose Use the constraint_clause in a CREATE TABLE or ALTER TABLE statement to define an integrity constraint. An integrity constraint is a rule that restricts the values for one or more columns in a table, an index-organized table, or a view. Note: Oracle does not...
SQL ALTER TABLE 语法如需在表中添加列,请使用下面的语法:ALTER TABLE table_nameDROP COLUMN column_name如需删除表中的列,请使用下面的语法(请注意...,某些数据库系统不允许这种在数据库表中删除列的方式):ALTER TABLE table_nameDROP C...
inlineUniquePK::=[CONSTRAINT<constraint_name>]{UNIQUE|PRIMARYKEY}[[NOT]ENFORCED][[NOT]DEFERRABLE][INITIALLY{DEFERRED|IMMEDIATE}][{ENABLE|DISABLE}][{VALIDATE|NOVALIDATE}][{RELY|NORELY}] inlineFK:=[CONSTRAINT<constraint_name>][FOREIGNKEY]REFERENCES<ref_table_name>[(<ref_col_name>)][MATCH{FULL|...
不支持 immutable_table_clauses 子句修改不可变表的定义,会报错。 不支持 blockchain_table_clauses 子句修改区块链表的定义,会报错。 不支持 memoptimize_read_clause 子句提高高频数据查询操作的性能,会报错。 不支持 memoptimize_write_clause 子句启用快速写入,会报错。 不支持 enable_disable_clause 子句定义数据...
Chapter 8, "SQL Statements: ALTER TABLE to constraint_clause" - Organization SQL Statements: ALTER CLUSTER to ALTER SYSTEM SQL Statements: ALTER TABLE to constraint_clause [ Previous book | Next book ]Advanced Security Administrator's Guide
次の文は、employees表の2つの制約をENABLE NOVALIDATE状態にします。ALTER TABLE employees ENABLE NOVALIDATE PRIMARY KEY ENABLE NOVALIDATE CONSTRAINT emp_last_name_nn; この文には、次の2つのENABLE句が含まれています。1番目のENABLE句は、表の主キー制約をENABLE NOVALIDATE状態にします。 2番目のENABLE...