ORACLE问题,每天10问(十二)

111. 返回大于等于N的最小整数值?

SELECT CEIL(N) FROM DUAL;

112. 返回小于等于N的最小整数值?

SELECT FLOOR(N) FROM DUAL;

113. 返回当前月的最后一天?

SELECT LAST_DAY(SYSDATE) FROM DUAL;

114. 如何不同用户间数据导入?

IMP SYSTEM/MANAGER FILE=AA.DMP FROMUSER=USER_OLD TOUSER=USER_NEW ROWS=Y INDEXES=Y ;

115. 如何找数据库表的主键字段的名称?

SQL>SELECT * FROM user_constraints WHERE CONSTRAINT_TYPE='P' and table_name='TABLE_NAME';

116. 两个结果集互加的函数?

SQL>SELECT * FROM BSEMPMS_OLD INTERSECT SELECT * FROM BSEMPMS_NEW;
SQL>SELECT * FROM BSEMPMS_OLD UNION SELECT * FROM BSEMPMS_NEW;
SQL>SELECT * FROM BSEMPMS_OLD UNION ALL SELECT * FROM BSEMPMS_NEW;

117. 两个结果集互减的函数?
SQL>SELECT * FROM BSEMPMS_OLD MINUS SELECT * FROM BSEMPMS_NEW;

118. 如何配置Sequence?

建sequence seq_custid
create sequence seq_custid start 1 incrememt by 1;

建表时:
create table cust
{ cust_id smallint not null,
...}
insert 时:
insert into table cust
values( seq_cust.nextval, ...)

119>.日期的各部分的常用的的写法

取时间点的年份的写法:

SELECT TO_CHAR(SYSDATE,'YYYY') FROM DUAL;

120>.取时间点的月份的写法:

SELECT TO_CHAR(SYSDATE,'MM') FROM DUAL;

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