oracle select 问题 SELECT 1 FROM epma.C_ACCT 什么意思? 为什么对一张表进行select 1 查询? 谢谢 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 select 1 from t就是值1的一列,select 'fuyou' from t所有的值都是fuyou我测试了是这样,不知道对不对 写这个SQL的人因该是想快速判断这张表里有没有数据 就是判断这个表中是否有数据,如果有的话就返回1,没有就返回空,你也可以select 任何一个数字类型,意义是一样的 不好意思。是返回1.如果是order by之类的数字几就是第几列SQL> select 1 from emp; 1---------- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 rows selected SQL> select * from emp order by 1; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO----- ---------- --------- ----- ----------- --------- --------- ------ 7369 SMITH CLERK 7902 1980-12-17 800.00 20 7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30 7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30 7566 JONES MANAGER 7839 1981-4-2 2975.00 20 7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30 7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30 7782 CLARK MANAGER 7839 1981-6-9 2450.00 10 7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20 7839 KING PRESIDENT 1981-11-17 5000.00 10 7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30 7876 ADAMS CLERK 7788 1987-5-23 1100.00 20 7900 JAMES CLERK 7698 1981-12-3 950.00 30 7902 FORD ANALYST 7566 1981-12-3 3000.00 20 7934 MILLER CLERK 7782 1982-1-23 1300.00 10 14 rows selected SQL> select * from emp order by 7; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO----- ---------- --------- ----- ----------- --------- --------- ------ 7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30 7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30 7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30 7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30 7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20 7839 KING PRESIDENT 1981-11-17 5000.00 10 7876 ADAMS CLERK 7788 1987-5-23 1100.00 20 7900 JAMES CLERK 7698 1981-12-3 950.00 30 7902 FORD ANALYST 7566 1981-12-3 3000.00 20 7934 MILLER CLERK 7782 1982-1-23 1300.00 10 7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30 7566 JONES MANAGER 7839 1981-4-2 2975.00 20 7369 SMITH CLERK 7902 1980-12-17 800.00 20 7782 CLARK MANAGER 7839 1981-6-9 2450.00 10 14 rows selected SQL> select * from emp order by 8; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO----- ---------- --------- ----- ----------- --------- --------- ------ 7782 CLARK MANAGER 7839 1981-6-9 2450.00 10 7839 KING PRESIDENT 1981-11-17 5000.00 10 7934 MILLER CLERK 7782 1982-1-23 1300.00 10 7566 JONES MANAGER 7839 1981-4-2 2975.00 20 7902 FORD ANALYST 7566 1981-12-3 3000.00 20 7876 ADAMS CLERK 7788 1987-5-23 1100.00 20 7369 SMITH CLERK 7902 1980-12-17 800.00 20 7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20 7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30 7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30 7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30 7900 JAMES CLERK 7698 1981-12-3 950.00 30 7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30 7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30 14 rows selected 楼上前辈,你sql代码是图吗,怎么弄的 通常用在 where 子句的 exists 部分,判断是否存在满足条件的记录 学Oracle有钱途吗?呵呵各位? linux下oracle监听问题 程序中怎么取得"describe test"的结果集 Oracle 时间间隔提取的问题??求解。 这两个sql 语句效果是不是一样的? 好题 关于一个表的空间回收的问题。 跪求大神帮个忙,我的HQL语句哪里写错了 一個簡單的sql 十分着急,游标出错怎么办? 谁有oracle11i的下载路径,必有重谢 删除表问题 一个简单问题。关于嵌套表的。
就是值1的一列,
select 'fuyou' from t
所有的值都是fuyou
我测试了是这样,不知道对不对
SQL> select 1 from emp;
1
----------
1
1
1
1
1
1
1
1
1
1
1
1
1
1
14 rows selected
SQL> select * from emp order by 1;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980-12-17 800.00 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30
7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981-4-2 2975.00 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30
7782 CLARK MANAGER 7839 1981-6-9 2450.00 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20
7839 KING PRESIDENT 1981-11-17 5000.00 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987-5-23 1100.00 20
7900 JAMES CLERK 7698 1981-12-3 950.00 30
7902 FORD ANALYST 7566 1981-12-3 3000.00 20
7934 MILLER CLERK 7782 1982-1-23 1300.00 10
14 rows selected
SQL> select * from emp order by 7;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30
7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30
7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30
7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30
7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20
7839 KING PRESIDENT 1981-11-17 5000.00 10
7876 ADAMS CLERK 7788 1987-5-23 1100.00 20
7900 JAMES CLERK 7698 1981-12-3 950.00 30
7902 FORD ANALYST 7566 1981-12-3 3000.00 20
7934 MILLER CLERK 7782 1982-1-23 1300.00 10
7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30
7566 JONES MANAGER 7839 1981-4-2 2975.00 20
7369 SMITH CLERK 7902 1980-12-17 800.00 20
7782 CLARK MANAGER 7839 1981-6-9 2450.00 10
14 rows selected
SQL> select * from emp order by 8;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
7782 CLARK MANAGER 7839 1981-6-9 2450.00 10
7839 KING PRESIDENT 1981-11-17 5000.00 10
7934 MILLER CLERK 7782 1982-1-23 1300.00 10
7566 JONES MANAGER 7839 1981-4-2 2975.00 20
7902 FORD ANALYST 7566 1981-12-3 3000.00 20
7876 ADAMS CLERK 7788 1987-5-23 1100.00 20
7369 SMITH CLERK 7902 1980-12-17 800.00 20
7788 SCOTT ANALYST 7566 1987-4-19 3000.00 20
7521 WARD SALESMAN 7698 1981-2-22 1250.00 500.00 30
7844 TURNER SALESMAN 7698 1981-9-8 1500.00 0.00 30
7499 ALLEN SALESMAN 7698 1981-2-20 1600.00 300.00 30
7900 JAMES CLERK 7698 1981-12-3 950.00 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.00 30
7654 MARTIN SALESMAN 7698 1981-9-28 1250.00 1400.00 30
14 rows selected
各位?