邏輯運算
AND，OR，NOT
......where 表達式1 and 表達式2；
......where 表達式2 and 表達式1；
SQL優化：
SQL在解析where時是從右向左解析的。所以：and 時應該將易假的放在右側，or時應該將易真的值放在右側
order by
order by 之后可以跟哪些內容呢？
order by + 列名，表達式 ，別名，序號
SQL> select ename,sal,sal*12 "年薪",sal+nvl(comm,0) from emp order by 2; ENAME SAL 年薪 SAL+NVL(COMM,0) ---------- ---------- ---------- --------------- SMITH 800 9600 800 JAMES 950 11400 950 ADAMS 1100 13200 1100 WARD 1250 15000 1750 MARTIN 1250 15000 2650 MILLER 1300 15600 1300 TURNER 1500 18000 1500 ALLEN 1600 19200 1900 CLARK 2450 29400 2450 BLAKE 2850 34200 2850 JONES 2975 35700 2975 ENAME SAL 年薪 SAL+NVL(COMM,0) ---------- ---------- ---------- --------------- SCOTT 3000 36000 3000 FORD 3000 36000 3000 KING 5000 60000 5000 已選擇14行。 SQL> set pagesize 100; SQL> set timing on; SQL> ed 已寫入 file afiedt.buf 1* select ename,sal,sal*12 "年薪",sal+nvl(comm,0) from emp order by "年薪" SQL> / ENAME SAL 年薪 SAL+NVL(COMM,0) ---------- ---------- ---------- --------------- SMITH 800 9600 800 JAMES 950 11400 950 ADAMS 1100 13200 1100 WARD 1250 15000 1750 MARTIN 1250 15000 2650 MILLER 1300 15600 1300 TURNER 1500 18000 1500 ALLEN 1600 19200 1900 CLARK 2450 29400 2450 BLAKE 2850 34200 2850 JONES 2975 35700 2975 SCOTT 3000 36000 3000 FORD 3000 36000 3000 KING 5000 60000 5000 已選擇14行。 已用時間: 00: 00: 00.08 SQL> ed 已寫入 file afiedt.buf 1* select ename,sal,sal*12 "年薪",sal+nvl(comm,0) from emp order by sal+nvl(comm,0) desc SQL> / ENAME SAL 年薪 SAL+NVL(COMM,0) ---------- ---------- ---------- --------------- KING 5000 60000 5000 FORD 3000 36000 3000 SCOTT 3000 36000 3000 JONES 2975 35700 2975 BLAKE 2850 34200 2850 MARTIN 1250 15000 2650 CLARK 2450 29400 2450 ALLEN 1600 19200 1900 WARD 1250 15000 1750 TURNER 1500 18000 1500 MILLER 1300 15600 1300 ADAMS 1100 13200 1100 JAMES 950 11400 950 SMITH 800 9600 800 已選擇14行。 已用時間: 00: 00: 00.13 SQL>
order 后有多列時，列名之間用逗號隔開，order by 會同時作用於多列，如下例：會在同一部門內升序，部門間再升序
SQL> set linesize 140; SQL> select * from emp order by deptno,sal; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7839 KING PRESIDENT 17-11月-81 5000 10 7369 SMITH CLERK 7902 17-12月-80 800 20 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7902 FORD ANALYST 7566 03-12月-81 3000 20 7900 JAMES CLERK 7698 03-12月-81 950 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 已選擇14行。 已用時間: 00: 00: 00.14 SQL>
desc 只作用於最近的一列，兩列都降序，需要兩個desc
SQL> select * from emp order by deptno,sal desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7839 KING PRESIDENT 17-11月-81 5000 10 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7902 FORD ANALYST 7566 03-12月-81 3000 20 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7369 SMITH CLERK 7902 17-12月-80 800 20 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7900 JAMES CLERK 7698 03-12月-81 950 30 已選擇14行。 已用時間: 00: 00: 00.12 SQL> select * from emp order by deptno desc,sal desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7900 JAMES CLERK 7698 03-12月-81 950 30 7902 FORD ANALYST 7566 03-12月-81 3000 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7369 SMITH CLERK 7902 17-12月-80 800 20 7839 KING PRESIDENT 17-11月-81 5000 10 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7934 MILLER CLERK 7782 23-1月 -82 1300 10 已選擇14行。 已用時間: 00: 00: 00.14 SQL>
按獎金由高到低
select * from emp order by comm desc，結果前面的值為NULL，數據在后面，應該將NULL放在后面，即：select * from emp order by comm desc nulls last;
已用時間: 00: 00: 00.14 SQL> select * from emp order by comm; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7900 JAMES CLERK 7698 03-12月-81 950 30 7902 FORD ANALYST 7566 03-12月-81 3000 20 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7369 SMITH CLERK 7902 17-12月-80 800 20 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 已選擇14行。 已用時間: 00: 00: 00.13 SQL> select * from emp order by comm desc; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 17-12月-80 800 20 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7902 FORD ANALYST 7566 03-12月-81 3000 20 7900 JAMES CLERK 7698 03-12月-81 950 30 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 已選擇14行。 已用時間: 00: 00: 00.11 SQL> ed 已寫入 file afiedt.buf 1* select * from emp order by comm desc SQL> select * from emp order by comm desc nulls last; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7900 JAMES CLERK 7698 03-12月-81 950 30 7902 FORD ANALYST 7566 03-12月-81 3000 20 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7369 SMITH CLERK 7902 17-12月-80 800 20 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 已選擇14行。 已用時間: 00: 00: 00.14 SQL>