Remove CHECK Constraint We can remove theCHECKconstraint using theDROPclause. For example, SQL Server, PostgreSQL, Oracle -- remove CHECK constraint named amountCKALTERTABLEOrdersDROPCONSTRAINTamountCK; MySQL -- remove CHECK constraint named amountCKALTERTABLEOrdersDROPCHECKamountCK; Also Read:...
mysql> create table f1 (r1 int constraint tb_f1_r1_chk1 check (mod(r1,3)=0)); Query OK, 0 rows affected (0.03 sec) mysql> create table f2 (r1 int constraint tb_f2_r1_chk1 check (mod(r1,3)=0) not enforced); Query OK, 0 rows affected (0.02 sec) 1. 2. 3. 4. 5. 这里...
SQL CHECK on ALTER TABLE To create aCHECKconstraint on the "Age" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEPersons ADDCHECK(Age>=18); To allow naming of aCHECKconstraint, and for defining aCHECKconstraint on multi...
mysql>insert into f1values(20,10,10);QueryOK,1rowaffected(0.01sec)mysql>insert into f1values(10,10,10);ERROR3819(HY000):Check constraint'tb_f1_r1_chk1'is violated.mysql>insert into f1values(20,-10,10);ERROR3819(HY000):Check constraint'tb_f1_r2_positive'is violated.mysql>insert into f1...
可以使用 SQL Server Management Studio 或 Transact-SQL 在表中创建检查约束,以指定 SQL Server 的一个或多个列中可接受的数据值。 要详细了解如何添加列约束,请参阅 ALTER TABLE column_constraint。 有关详细信息,请参阅 Unique 约束和 check 约束。 备注 若要查询现有的检查约束,请使用 sys.check_constraints...
1.完整性约束:主键 (constraint) 主键能够标识唯一一条记录,主键不能为空,也不能重复 mysql> create table t_emp(empno int primary key,ename varchar(20),esex char(2)); Query OK, 0 rows affected (0.20 sec) mysql> show tables; +---+ | Tables_in_study |...
Query OK, 0 rows affected (0.02 sec) 这里CHECK 约束的相关限制如下: 1. constraint 名字在每个数据库中唯一。 也就是说单个数据库里不存在相同的两个 constraint,如果不定义,系统自动生成一个唯一的约束名字。 2. check 约束针对语句 insert/update/replace/load data/load xml 生效;针对对应的 ignore 语句失...
问为什么我不能在现有表中添加一个引用SQL中其他列的checkConstraint的列ENSQL是IT行业很多岗位都要求具备...
1 row in set (0.00 sec) mysql> CREATE TABLE t1 -> ( -> c1 INT CHECK (c1 > 10), -> c2 INT , -> c3 INT CHECK (c3 < 100), -> CONSTRAINT c2_positive CHECK (c2 > 0), -> CHECK (c1 > c3) -> ); Query OK, 0 rows affected (0.33 sec) ...
sql query with check constraint pct Amit Kumar June 08, 2023 08:42AM Re: sql query with check constraint pct Barry Galbraith June 08, 2023 07:21PM Sorry, you can't reply to this topic. It has been closed. This forum is currently read only. You can not log in or make any changes...