CONSTRAINT constraint_name CHECK (column_name condition) [DISABLE] ); The DISABLE keyword is optional. If you create a check constraint using the DISABLE keyword, the constraint will be created, but the condition will not be enforced. Example CREATE TABLE suppliers ( supplier_id numeric(4), su...
Creating Oracle Check constraint examples The following example creates thepartstable whose buy prices are positive: CREATETABLEparts ( part_idNUMBERGENERATEDBYDEFAULTASIDENTITY, part_nameVARCHAR2(255)NOTNULL, buy_priceNUMBER(9,2)CHECK(buy_price >0), PRIMARYKEY(part_id) );Code language:SQL (Stru...
Because whenever runs a query against the column, Check Constraint enforces the condition. In the first example Deptno value is 30 which is satisfying the Check Constraint condition but in the second example Deptno value is 50 which is violating the Check Constraint condition. That is why the s...
A check constraint is a Boolean expression that evaluates to either TRUE or FALSE. If the check constraint evaluates to FALSE, the SQL statement that caused the result returns an error. For example, a check constraint might require the minimum balance in a bank account to be over $100. If...
(sno number(5) constraint pk_t_pk4_sno primary key using index tablespace example, sname varchar2(20), idcard varchar2(18), createtime date ); 5、表级定义主键,自定义主键名称,并且指定索引使用的表空间 create table t_pk5 (sno number(5), ...
1)这对属性定义是否defer. Deferred: check on commit; immediate: check immediate. 2)If constraint is not deferrable,immediate is only choice. 3) For example: 复制 CREATE TABLE games(scores NUMBER, CONSTRAINT unq_num UNIQUE (scores)INITIALLY DEFERRED DEFERRABLE);insert into games values(1);insert...
1) 这对属性定义是否defer. Deferred: check on commit; immediate: check immediate. 2) If constraint is not deferrable,immediate is only choice. 3) For example: CREATE TABLE games (scores NUMBER, CONSTRAINT unq_num UNIQUE (scores) INITIALLY DEFERRED DEFERRABLE); ...
The condition of a CHECK constraint Also, within a single SQL statement that uses CURRVAL or NEXTVAL, all referenced LONG columns, updated tables, and locked tables must be located on the same database. How to Use Sequence Values When you create a sequence, you can define its initial ...
Example:做一个日志用来记录scott用户的一些操作: 首先在sysdba权限下建立日志表,序列,触发器: CREATE TABLE object_log( logid NUMBER CONSTRAINT pk_logid PRIMARY KEY, operatedate DATE NOT NULL, objecttype VARCHAR2(50) NOT NULL, objectowner VARCHAR2(50) NOT NULL );CREATE SEQUENCE obj_log_seq;CREAT...
Each column must be suitable for unique constraints. For example, a column of type CLOB is not suitable as a column in unique constraints. A unique constraint must not contain the same columns as the primary key. A unique constraint must not contain the same columns as another unique constrai...