oracle SQL集锦
下面的语句都是本人整理出的，并且都在oracle XE上测试通过。下边的函数都没有做说明，相信大家都知道怎么用了，呵呵。
1
普通的查询语句，例如：
SELECT
last_name, department_id
FROM
employees;
2
查询视图
SELECT
employee_id, last_name, job_title, department_name, country_name, region_name
FROM
emp_details_view;
3
更换列名查询
SELECT
employee_id "Employee ID
number
", last_name "Employee last name", first_name "Employee first name"
FROM
employees;
4
联接查询 自然联接：要求两个表中的公共列必须有相同的名称和结构类型，否则报错。
SELECT
employee_id, last_name, first_name, department_id, department_name, manager_id
FROM
employees NATURAL
JOIN
departments; 查询三张或以上表时用USING，前提是用来连接两张表的列必须名称相同。
SELECT
e.employee_id, e.last_name, e.first_name, e.manager_id, department_id, d.department_name, d.manager_id
FROM
employees e
JOIN
departments d USING (department_id); 联接时加上WHERE 子句。
SELECT
e.employee_id, e.last_name, e.first_name, e.department_id, d.department_name, d.manager_id, d.location_id, l.country_id
FROM
employees e
JOIN
departments d
ON
e.department_id
=
d.department_id
JOIN
locations l
ON
d.location_id
=
l.location_id
WHERE
l.location_id
=
1700
; 自我联接：
SELECT
e.employee_id emp_id, e.last_name emp_lastname, m.employee_id mgr_id, m.last_name mgr_lastname
FROM
employees e
JOIN
employees m
ON
e.manager_id
=
m.employee_id;
LEFT
OUTER
JOIN
：左表中所有的记录即使在右表中没有联接的都会被查询出来。
SELECT
e.employee_id, e.last_name, e.department_id, d.department_name
FROM
employees e
LEFT
OUTER
JOIN
departments d
ON
(e.department_id
=
d.department_id);
RIGHT
OUTER
JOIN
：右表中所有的记录即使在左表中没有联接的都会被查询出来。
SELECT
e.employee_id, e.last_name, e.department_id, d.department_name
FROM
employees e
RIGHT
OUTER
JOIN
departments d
ON
(e.department_id
=
d.department_id);
FULL
OUTER
JOIN
：左右表中的记录全部被查询出来。
SELECT
e.employee_id, e.last_name, e.department_id, d.department_name
FROM
employees e
FULL
OUTER
JOIN
departments d
ON
(e.department_id
=
d.department_id);
5
绑定变量查询：Oracle将已解析、已编译的SQL连同其他内容存储在共享池中，这是SGA中一个非常重要的存储结构（内存结构主要分为SGA和PGA）。而绑定变量查询在Oracle里执行时只编译一次，随后就会把这个查询计划存储在一个共享池中以便重用，即所谓的软解析。具体的使用方法如下：
SELECT
*
FROM
employees
WHERE
employee_id
=
:employee_id
6
查询虚拟列：所谓的虚拟列在Oracle里类似表格的列，但并非存储在表中。查询虚拟列时将返回一个值，因此它又类似与函数。Oracle里的虚拟列有：ROWNUM, SYSDATE,
and
USER
。eg：
SELECT
SYSDATE "NOW"
FROM
DUAL;
SELECT
USER
FROM
DUAL;
SELECT
employee_id, hire_date, SYSDATE
FROM
employees
WHERE
ROWNUM
<
10
;
7
带函数查询： Using Numeric Functions：
SELECT
employee_id,
ROUND
(salary
/
30
,
2
) "Salary per
day
"
FROM
employees;
SELECT
employee_id, TRUNC(salary
/
30
,
0
) "Salary per
day
"
FROM
employees;
SELECT
employee_id, MOD(employee_id,
2
)
FROM
employees; Using
Character
Functions：
SELECT
employee_id,
UPPER
(last_name),
LOWER
(first_name)
FROM
employees;
SELECT
employee_id, INITCAP(first_name), INITCAP(last_name)
FROM
employees;
SELECT
employee_id,
RTRIM
(first_name)
||
'
'
||
LTRIM
(last_name)
FROM
employees;
SELECT
employee_id, TRIM(last_name)
||
'
,
'
||
TRIM(first_name)
FROM
employees;
SELECT
employee_id, RPAD(last_name,
30
,
'
'
), first_name
FROM
employees;
SELECT
employee_id, SUBSTR(last_name,
1
,
10
)
FROM
employees;
SELECT
LENGTH(last_name)
FROM
employees;
SELECT
employee_id,
REPLACE
(job_id,
'
SH
'
,
'
SHIPPING
'
)
FROM
employees
WHERE
SUBSTR(job_id,
1
,
2
)
=
'
SH
'
; Using Date Functions：
SELECT
employee_id, TRUNC(MONTHS_BETWEEN(SYSDATE, HIRE_DATE)) "Months Employed"
FROM
employees;
SELECT
employee_id, EXTRACT(
YEAR
FROM
hire_date) "
Year
Hired"
FROM
employees;
SELECT
EXTRACT(
YEAR
FROM
SYSDATE)
||
EXTRACT(
MONTH
FROM
SYSDATE)
||
EXTRACT(
DAY
FROM
SYSDATE) "
Current
Date"
FROM
DUAL;
SELECT
employee_id, hire_date, ADD_MONTHS(hire_date,
3
)
FROM
employees;
SELECT
employee_id, hire_date, LAST_DAY(hire_date) "Last
day
of
month
"
FROM
employees;
SELECT
SYSTIMESTAMP
FROM
DUAL; Using Conversion Functions：
SELECT
TO_CHAR(SYSDATE,
'
DD-MON-YYYY AD
'
) "Today"
FROM
DUAL;
SELECT
TO_CHAR(SYSDATE,
'
FMMonth DD YYYY
'
) "Today"
FROM
DUAL;
SELECT
TO_CHAR(SYSDATE,
'
MM-DD-YYYY HH24:MI:SS
'
) "Now"
FROM
DUAL;
SELECT
hire_date, TO_CHAR(hire_date,
'
DS
'
) "Short Date"
FROM
employees;
SELECT
hire_date, TO_CHAR(hire_date,
'
DL
'
) "
Long
Date"
FROM
employees;
SELECT
TO_CHAR(EXTRACT(
YEAR
FROM
SYSDATE))
||
TO_CHAR(EXTRACT(
MONTH
FROM
SYSDATE),
'
FM09
'
)
||
TO_CHAR(EXTRACT(
DAY
FROM
SYSDATE),
'
FM09
'
) "
Current
Date"
FROM
DUAL;
SELECT
TO_CHAR(
CURRENT_DATE
,
'
DD-MON-YYYY HH24:MI:SS
'
) "
Current
Date"
FROM
DUAL;
SELECT
TO_CHAR(salary,
'
$99,999.99
'
) salary
FROM
employees;
SELECT
TO_NUMBER(
'
1234.99
'
)
+
500
FROM
DUAL;
SELECT
TO_NUMBER(
'
11,200.34
'
,
'
99G999D99
'
)
+
1000
FROM
DUAL;
SELECT
TO_DATE(
'
27-OCT-98
'
,
'
DD-MON-RR
'
)
FROM
DUAL;
SELECT
TO_DATE(
'
28-Nov-05 14:10:10
'
,
'
DD-Mon-YY HH24:MI:SS
'
)
FROM
DUAL;
SELECT
TO_DATE(
'
January 15, 2006, 12:00 A.M.
'
,
'
Month dd, YYYY, HH:MI A.M.
'
)
FROM
DUAL;
SELECT
TO_TIMESTAMP(
'
10-Sep-05 14:10:10.123000
'
,
'
DD-Mon-RR HH24:MI:SS.FF
'
)
FROM
DUAL; Using Aggregate Functions：
SELECT
COUNT
(
*
) "Employee
Count
"
FROM
employees
WHERE
manager_id
=
122
;
SELECT
COUNT
(
*
) "Employee
Count
", manager_id
FROM
employees
GROUP
BY
manager_id
ORDER
BY
manager_id
SELECT
COUNT
(commission_pct)
FROM
employees;
SELECT
COUNT
(
DISTINCT
department_id)
FROM
employees;
SELECT
MIN
(salary),
MAX
(salary),
AVG
(salary), job_id
FROM
employees
GROUP
BY
job_id
ORDER
BY
job_id;
SELECT
RANK(
2600
) WITHIN
GROUP
(
ORDER
BY
salary
DESC
) "Rank
of
$
2
,
600
among clerks"
FROM
employees
WHERE
job_id
LIKE
'
%CLERK
'
;
SELECT
job_id, employee_id, last_name, salary, DENSE_RANK()
OVER
(PARTITION
BY
job_id
ORDER
BY
salary
DESC
) "Salary Rank (Dense)"
FROM
employees
WHERE
job_id
=
'
SH_CLERK
'
;
SELECT
employee_id, salary, hire_date, STDDEV(salary)
OVER
(
ORDER
BY
hire_date) "Std Deviation
of
Salary"
FROM
employees
WHERE
job_id
=
'
ST_CLERK
'
; Using
NULL
Value Functions：
SELECT
commission_pct, NVL(commission_pct,
0
)
FROM
employees;
SELECT
phone_number, NVL(phone_number,
'
MISSING
'
)
FROM
employees;
SELECT
employee_id , last_name,commission_pct, salary, NVL2(commission_pct, salary
+
(salary
*
commission_pct), salary) income
FROM
employees; Using Conditional Functions：
SELECT
employee_id, hire_date , salary,
CASE
WHEN
hire_date
<
TO_DATE(
'
01-JAN-90
'
)
THEN
salary
*
1.20
WHEN
hire_date
<
TO_DATE(
'
01-JAN-92
'
)
THEN
salary
*
1.15
WHEN
hire_date
<
TO_DATE(
'
01-JAN-94
'
)
THEN
salary
*
1.10
ELSE
salary
*
1.05
END
"Revised Salary"
FROM
employees;
SELECT
employee_id, job_id , salary, DECODE(job_id,
'
PU_CLERK
'
, salary
*
1.05
,
'
SH_CLERK
'
, salary
*
1.10
,
'
ST_CLERK
'
, salary
*
1.15
, salary) "Revised Salary"
FROM
employees;