USING
ALIASES:
CREATE
WITH SELECT
We
can create a table using existing table [along with data].
Syntax:
Create table
<new_table_name>
[col1,
col2, col3 ... coln]
as select * from
<old_table_name>;
Ex:
SQL>
create table student1 as select * from student;
Creating table
with your own column names.
SQL>
create table student2(sno, sname, smarks) as select * from student;
Creating
table with specified columns.
SQL>
create table student3 as select no,name from student;
Creating
table with out table data.
SQL>
create table student2(sno, sname, smarks) as select * from student
where 1 = 2;
In
the above where clause give any condition which does not satisfy.
INSERT
WITH SELECT
Using
this we can insert existing table data to a another table in a single
trip. But the table structure should be same.
Syntax:
Insert into
<table1>
select * from <table2>;
Ex:
SQL>
insert into student1 select * from student;
Inserting data
into specified columns
SQL>
insert into student1(no, name) select no, name from student;
COLUMN
ALIASES
Syntax:
Select
<orginal_col> <alias_name> from <table_name>;
Ex:
SQL>
select no sno from student;
or
SQL>
select no “sno” from student;
TABLE
ALIASES
If
you are using table aliases you can use dot method to the columns.
Syntax:
Select
<alias_name>.<col1>,
<alias_name>.<col2>
… <alias_name>.<coln>
from
<table_name>
<alias_name>;
Ex:
SQL>
select s.no, s.name from student s;
USING
MERGE:
MERGE
You
can use merge command to perform insert and update in a single
command.
Ex:
SQL>
Merge into student1 s1
Using (select
*From student2) s2
On(s1.no=s2.no)
When matched
then
Update set
marks = s2.marks
When not
matched then
Insert
(s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.marks);
In
the above the two tables are with the same structure but we can merge
different structured
tables
also but the datatype of the columns should match.
Assume
that student1 has columns like no,name,marks and student2 has columns
like no,
name,
hno, city.
SQL>
Merge into student1 s1
Using (select
*From student2) s2
On(s1.no=s2.no)
When matched
then
Update set
marks = s2.hno
When not
matched then
Insert
(s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.hno);
MULTIPLE
INSERTS:
We
have table called DEPT with the following columns and data
DEPTNO DNAME LOC
-------- -------- ----
10 accounting new
york
20 research
dallas
30 sales
Chicago
40 operations boston
a)
CREATE
STUDENT TABLE
SQL>
Create table student(no number(2),name varchar(2),marks number(3));
b)
MULTI
INSERT WITH ALL FIELDS
SQL>
Insert all
Into
student values(1,’a’,100)
Into
student values(2,’b’,200)
Into
student values(3,’c’,300)
Select
*from dept where deptno=10;
-- This inserts
3 rows
c)
MULTI
INSERT WITH SPECIFIED FIELDS
SQL>
insert all
Into
student (no,name) values(4,’d’)
Into
student(name,marks) values(’e’,400)
Into
student values(3,’c’,300)
Select
*from dept where deptno=10;
-- This inserts
3 rows
d)
MULTI
INSERT WITH DUPLICATE ROWS
SQL>
insert all
Into
student values(1,’a’,100)
Into
student values(2,’b’,200)
Into
student values(3,’c’,300)
Select
*from dept where deptno > 10;
-- This inserts
9 rows because in the select statement retrieves 3 records (3 inserts
for each
row
retrieved)
e)
MULTI
INSERT WITH CONDITIONS BASED
SQL>
Insert all
When
deptno > 10 then
Into
student1 values(1,’a’,100)
When
dname = ‘SALES’ then
Into
student2 values(2,’b’,200)
When loc
= ‘NEW YORK’ then
Into
student3 values(3,’c’,300)
Select
*from dept where deptno>10;
-- This inserts
4 rows because the first condition satisfied 3 times, second
condition
satisfied
once and the last none.
f)
MULTI
INSERT WITH CONDITIONS BASED AND ELSE
SQL>
Insert
all
When
deptno > 100 then
Into
student1 values(1,’a’,100)
When
dname = ‘S’ then
Into
student2 values(2,’b’,200)
When loc
= ‘NEW YORK’ then
Into
student3 values(3,’c’,300)
Else
Into
student values(4,’d’,400)
Select
*from dept where deptno>10;
-- This inserts
3 records because the else satisfied 3 times
g)
MULTI
INSERT WITH CONDITIONS BASED AND FIRST
SQL>
Insert
first
When
deptno = 20 then
Into
student1 values(1,’a’,100)
When
dname = ‘RESEARCH’ then
Into
student2 values(2,’b’,200)
When loc
= ‘NEW YORK’ then
Into
student3 values(3,’c’,300)
Select
*from dept where deptno=20;
-- This inserts
1 record because the first clause avoid to check the remaining
conditions
once the
condition is satisfied.
h)
MULTI
INSERT WITH CONDITIONS BASED, FIRST AND ELSE
SQL>
Insert
first
When
deptno = 30 then
Into
student1 values(1,’a’,100)
When
dname = ‘R’ then
Into
student2 values(2,’b’,200)
When
loc = ‘NEW YORK’ then
Into
student3 values(3,’c’,300)
Else
Into
student values(4,’d’,400)
Select
*from dept where deptno=20;
-- This inserts
1 record because the else clause satisfied once
i)
MULTI
INSERT WITH MULTIBLE TABLES
SQL>
Insert
all
Into
student1 values(1,’a’,100)
Into
student2 values(2,’b’,200)
Into
student3 values(3,’c’,300)
Select
*from dept where deptno=10;
-- This inserts 3
rows
** You can use
multi tables with specified fields, with duplicate rows, with
conditions, with
first and
else clauses.
FUNCTIONS:
Functions
can be categorized as follows.
- Single row functions
- Group functions
SINGLE
ROW FUNCTIONS
Single
row functions can be categorized into five. These will be applied for
each row and produces individual output for each row.
- Numeric functions
- String functions
- Date functions
- Miscellaneous functions
- Conversion functions
NUMERIC
FUNCTIONS
- Abs
- Sign
- Sqrt
- Mod
- Nvl
- Power
- Exp
- Ln
- Log
- Ceil
- Floor
- Round
- Trunk
- Bitand
- Greatest
- Least
- Coalesce
a)
ABS
Absolute value
is the measure of the magnitude of value.
Absolute value
is always a positive number.
Syntax:
abs (value)
Ex:
SQL>
select abs(5), abs(-5), abs(0), abs(null) from dual;
ABS(5)
ABS(-5) ABS(0) ABS(NULL)
----------
---------- ---------- -------------
5
-5 0
b)
SIGN
Sign gives the
sign of a value.
Syntax:
sign (value)
Ex:
SQL>
select sign(5), sign(-5), sign(0), sign(null) from dual;
SIGN(5)
SIGN(-5) SIGN(0) SIGN(NULL)
----------
---------- ---------- --------------
1
-1 0
c)
SQRT
This will give
the square root of the given value.
Syntax:
sqrt (value) --
here value must be positive.
Ex:
SQL>
select sqrt(4), sqrt(0), sqrt(null), sqrt(1) from dual;
SQRT(4)
SQRT(0) SQRT(NULL) SQRT(1)
----------
---------- --------------- ----------
2
0 1
d)
MOD
This will give
the remainder.
Syntax:
mod (value,
divisor)
Ex:
SQL>
select mod(7,4), mod(1,5), mod(null,null), mod(0,0), mod(-7,4) from
dual;
MOD(7,4)
MOD(1,5) MOD(NULL,NULL) MOD(0,0) MOD(-7,4)
------------
---------- --------------------- ----------- -------------
3
1 0 -3
e)
NVL
This will
substitutes the specified value in the place of null values.
Syntax:
nvl (null_col,
replacement_value)
Ex:
SQL>
select * from student; --
here for 3rd
row marks value is null
NO NAME
MARKS
---
------- ---------
1 a
100
2 b
200
3 c
SQL>
select no, name, nvl(marks,300) from student;
NO NAME
NVL(MARKS,300)
---
------- ---------------------
1 a
100
2 b 200
3 c
300
SQL>
select nvl(1,2), nvl(2,3), nvl(4,3), nvl(5,4) from dual;
NVL(1,2)
NVL(2,3) NVL(4,3) NVL(5,4)
----------
---------- ---------- ----------
1
2 4 5
SQL>
select nvl(0,0), nvl(1,1), nvl(null,null), nvl(4,4) from dual;
NVL(0,0)
NVL(1,1) NVL(null,null) NVL(4,4)
----------
---------- ----------------- ----------
0
1 4
f)
POWER
Power is the
ability to raise a value to a given exponent.
Syntax:
power (value,
exponent)
Ex:
SQL>
select power(2,5), power(0,0), power(1,1), power(null,null),
power(2,-5) from
dual;
POWER(2,5)
POWER(0,0) POWER(1,1) POWER(NULL,NULL) POWER(2,-5)
--------------
-------------- ----- --------- -----------------------
---------------
32
1 1
.03125
g)
EXP
This will raise
e value to the give power.
Syntax:
exp (value)
Ex:
SQL>
select exp(1), exp(2), exp(0), exp(null), exp(-2) from dual;
EXP(1)
EXP(2) EXP(0) EXP(NULL) EXP(-2)
--------
--------- -------- ------------- ----------
2.71828183
7.3890561 1 .135335283
h)
LN
This is based on
natural or base e logarithm.
Syntax:
ln (value) --
here value must be greater than zero which is positive only.
Ex:
SQL>
select ln(1), ln(2), ln(null) from dual;
LN(1)
LN(2) LN(NULL)
-------
------- ------------
0
.693147181
Ln and Exp
are reciprocal to each other.
EXP
(3) = 20.0855369
LN
(20.0855369) = 3
i)
LOG
This is based on
10 based logarithm.
Syntax:
log (10, value) --
here value must be greater than zero which is positive only.
Ex:
SQL>
select log(10,100), log(10,2), log(10,1), log(10,null) from dual;
LOG(10,100)
LOG(10,2) LOG(10,1) LOG(10,NULL)
---------------
----------- ------------ -----------------
2
.301029996 0
LN
(value) = LOG
(EXP(1),
value)
SQL>
select ln(3), log(exp(1),3) from dual;
LN(3)
LOG(EXP(1),3)
-------
-----------------
1.09861229
1.09861229
j)
CEIL
This will
produce a whole number that is greater than or equal to the specified
value.
Syntax:
ceil (value)
Ex:
SQL>
select ceil(5), ceil(5.1), ceil(-5), ceil( -5.1), ceil(0), ceil(null)
from dual;
CEIL(5)
CEIL(5.1) CEIL(-5) CEIL(-5.1) CEIL(0) CEIL(NULL)
---------
----------- ---------- ------------ -------- --------------
5
6 -5 -5 0
k)
FLOOR
This will
produce a whole number that is less than or equal to the specified
value.
Syntax:
floor (value)
Ex:
SQL>
select floor(5), floor(5.1), floor(-5), floor( -5.1), floor(0),
floor(null) from dual;
FLOOR(5)
FLOOR(5.1) FLOOR(-5) FLOOR(-5.1) FLOOR(0) FLOOR(NULL)
-----------
------------- ------------ -------------- -----------
----------------
5
5 -5 -6
0
l)
ROUND
This will rounds
numbers to a given number of digits of precision.
Syntax:
round (value,
precision)
Ex:
SQL>
select round(123.2345), round(123.2345,2), round(123.2354,2) from
dual;
ROUND(123.2345)
ROUND(123.2345,0) ROUND(123.2345,2) ROUND(123.2354,2)
---------------------
------------------------ -----------------------
-----------------------
123
123 123.23
123.24
SQL>
select round(123.2345,-1), round(123.2345,-2), round(123.2345,-3),
round(123.2345,-4)
from dual;
ROUND(123.2345,-1)
ROUND(123.2345,-2) ROUND(123.2345,-3) ROUND(123.2345,-4)
------------------------
------------------------- ------------------------
------------------------
120
100 0
0
SQL>
select round(123,0), round(123,1), round(123,2) from dual;
ROUND(123,0)
ROUND(123,1) ROUND(123,2)
-----------------
----------------- ----------------
123
123 123
SQL>
select round(-123,0), round(-123,1), round(-123,2) from dual;
ROUND(-123,0)
ROUND(-123,1) ROUND(-123,2)
------------------
----------------- -------------------
-123
-123 -123
SQL>
select round(123,-1), round(123,-2), round(123,-3), round(-123,-1),
round(-123,-
2),
round(-123,-3) from dual;
ROUND(123,-1)
ROUND(123,-2) ROUND(123,-3) ROUND(-123,-1) ROUND(-123,-2)
ROUND(-123,-3)
-------------
------------- ------------- -------------- --------------
--------------
120
100 0 -120 -100
0
SQL>
select round(null,null), round(0,0), round(1,1), round(-1,-1),
round(-2,-2) from
dual;
ROUND(NULL,NULL)
ROUND(0,0) ROUND(1,1) ROUND(-1,-1) ROUND(-2,-2)
-----------------------
-------------- -------------- ---------------- ----------------
0
1 0 0
m)
TRUNC
This will
truncates or chops off digits of precision from a number.
Syntax:
trunc (value,
precision)
Ex:
SQL>
select trunc(123.2345), trunc(123.2345,2), trunc(123.2354,2) from
dual;
TRUNC(123.2345)
TRUNC(123.2345,2) TRUNC(123.2354,2)
---------------------
----------------------- -----------------------
123
123.23 123.23
SQL>
select trunc(123.2345,-1), trunc(123.2345,-2), trunc(123.2345,-3),
trunc(123.2345,-4)
from dual;
TRUNC(123.2345,-1)
TRUNC(123.2345,-2) TRUNC(123.2345,-3) TRUNC(123.2345,-4)
------------------------
------------------------ -----------------------
------------------------
120
100 0
0
SQL>
select trunc(123,0), trunc(123,1), trunc(123,2) from dual;
TRUNC(123,0)
TRUNC(123,1) TRUNC(123,2)
----------------
---------------- -----------------
123
123 123
SQL>
select trunc(-123,0), trunc(-123,1), trunc(-123,2) from dual;
TRUNC(-123,0)
TRUNC(-123,1) TRUNC(-123,2)
-----------------
----------------- -----------------
-123
-123 -123
SQL>
select
trunc(123,-1), trunc(123,-2), trunc(123,-3), trunc(-123,-1),
trunc(-123,2),
trunc(-123,-3)
from dual;
TRUNC(123,-1)
TRUNC(123,-2) TRUNC(123,-3) TRUNC(-123,-1) TRUNC(-123,2) TRUNC(-
123,-3)
-------------
------------- ------------- -------------- -------------
--------------
120
100 0 -120 -123
0
SQL>
select trunc(null,null), trunc(0,0), trunc(1,1), trunc(-1,-1),
trunc(-2,-2) from dual;
TRUNC(NULL,NULL)
TRUNC(0,0) TRUNC(1,1) TRUNC(-1,-1) TRUNC(-2,-2)
-----------------------
------------- ------------- --------------- ----------------
0 1
0 0
n)
BITAND
This will
perform bitwise and operation.
Syntax:
bitand (value1,
value2)
Ex:
SQL>
select bitand(2,3), bitand(0,0), bitand(1,1), bitand(null,null),
bitand(-2,-3) from
dual;
BITAND(2,3)
BITAND(0,0) BITAND(1,1) BITAND(NULL,NULL) BITAND(-2,-3)
--------------
--------------- -------------- ------------------------
-----------------
2
0 1 -4
o)
GREATEST
This will give
the greatest number.
Syntax:
greatest (value1,
value2, value3 … valuen)
Ex:
SQL>
select greatest(1, 2, 3), greatest(-1, -2, -3) from dual;
GREATEST(1,2,3)
GREATEST(-1,-2,-3)
--------------------
-----------------------
3
-1
- If all the values are zeros then it will display zero.
- If all the parameters are nulls then it will display nothing.
- If any of the parameters is null it will display nothing.
p)
LEAST
This will give
the least number.
Syntax:
least (value1,
value2, value3 … valuen)
Ex:
SQL>
select least(1, 2, 3), least(-1, -2, -3) from dual;
LEAST(1,2,3)
LEAST(-1,-2,-3)
--------------------
-----------------------
1
-3
- If all the values are zeros then it will display zero.
- If all the parameters are nulls then it will display nothing.
- If any of the parameters is null it will display nothing.
q)
COALESCE
This will return
first non-null value.
Syntax:
coalesce (value1,
value2, value3 … valuen)
Ex:
SQL>
select
coalesce(1,2,3), coalesce(null,2,null,5) from dual;
COALESCE(1,2,3)
COALESCE(NULL,2,NULL,5)
-------------------
-------------------------------
1
2
STRING
FUNCTIONS
- Initcap
- Upper
- Lower
- Length
- Rpad
- Lpad
- Ltrim
- Rtrim
- Trim
- Translate
- Replace
- Soundex
- Concat ( ‘ || ‘ Concatenation operator)
- Ascii
- Chr
- Substr
- Instr
- Decode
- Greatest
- Least
- Coalesce
a)
INITCAP
This will
capitalize the initial letter of the string.
Syntax:
initcap (string)
Ex:
SQL>
select initcap('computer') from dual;
INITCAP
-----------
Computer
b)
UPPER
This will
convert the string into uppercase.
Syntax:
upper (string)
Ex:
SQL>
select upper('computer') from dual;
UPPER
-----------
COMPUTER
c)
LOWER
This will
convert the string into lowercase.
Syntax:
lower (string)
Ex:
SQL>
select lower('COMPUTER')
from dual;
LOWER
-----------
computer
d)
LENGTH
This will give
length of the string.
Syntax:
length (string)
Ex:
SQL>
select length('computer') from dual;
LENGTH
-----------
8
e)
RPAD
This will allows
you to pad the right side of a column with any set of characters.
Syntax:
rpad (string,
length [, padding_char])
Ex:
SQL>
select rpad('computer',15,'*'), rpad('computer',15,'*#') from dual;
RPAD('COMPUTER'
RPAD('COMPUTER'
----------------------
----------------------
computer*******
computer*#*#*#*
--
Default padding character was blank space.
f)
LPAD
This will allows
you to pad the left side of a column with any set of characters.
Syntax:
lpad (string,
length [, padding_char])
Ex:
SQL>
select lpad('computer',15,'*'), lpad('computer',15,'*#') from dual;
LPAD('COMPUTER'
LPAD('COMPUTER'
---------------------
---------------------
*******computer
*#*#*#*computer
--
Default padding character was blank space.
g)
LTRIM
This will trim
off unwanted characters from the left end of string.
Syntax:
ltrim (string
[,unwanted_chars])
Ex:
SQL>
select ltrim('computer','co'), ltrim('computer','com') from dual;
LTRIM(
LTRIM
--------
---------
mputer
puter
SQL>
select ltrim('computer','puter'), ltrim('computer','omputer') from
dual;
LTRIM('C
LTRIM('C
----------
----------
computer
computer
-- If you
haven’t specify any unwanted characters it will display entire
string.
h)
RTRIM
This will trim
off unwanted characters from the right end of string.
Syntax:
rtrim (string
[, unwanted_chars])
Ex:
SQL>
select rtrim('computer','er'), rtrim('computer','ter') from dual;
RTRIM(
RTRIM
--------
---------
comput
compu
SQL>
select rtrim('computer','comput’), rtrim('computer','compute') from
dual;
RTRIM('C
RTRIM('C
----------
----------
computer
computer
-- If you
haven’t specify any unwanted characters it will display entire
string.
i)
TRIM
This will trim
off unwanted characters from the both sides of string.
Syntax:
trim (unwanted_chars
from
string)
Ex:
SQL>
select trim( 'i' from 'indiani') from dual;
TRIM(
-----
ndian
SQL>
select trim( leading'i' from 'indiani') from dual; -- this will work
as LTRIM
TRIM(L
------
ndiani
SQL>
select trim( trailing'i' from 'indiani') from dual; -- this will work
as RTRIM
TRIM(T
------
Indian
j)
TRANSLATE
This will
replace the set of characters, character by character.
Syntax:
translate (string,
old_chars, new_chars)
Ex:
SQL>
select translate('india','in','xy') from dual;
TRANS
--------
xydxa
k)
REPLACE
This will
replace the set of characters, string by string.
Syntax:
replace (string,
old_chars [, new_chars])
Ex:
SQL>
select replace('india','in','xy'), replace(‘india’,’in’) from
dual;
REPLACE
REPLACE
-----------
-----------
Xydia
dia
l)
SOUNDEX
This will be used
to find words that sound like other words, exclusively used in where
clause.
Syntax:
soundex (string)
Ex:
SQL>
select * from emp where soundex(ename) = soundex('SMIT');
EMPNO ENAME
JOB MGR HIREDATE SAL DEPTNO
--------
-------- ----- ----- ------------ ---------
----------
7369 SMITH
CLERK 7902 17-DEC-80 500 20
m)
CONCAT
This will be used
to combine two strings only.
Syntax:
concat (string1,
string2)
Ex:
SQL>
select concat('computer',' operator') from dual;
CONCAT('COMPUTER'
-------------------------
computer
operator
If you want to
combine more than two strings you have to use concatenation operator
(||).
SQL>
select 'how' || ' are' || ' you' from dual;
'HOW'||'ARE
---------------
how
are you
n)
ASCII
This will return
the decimal representation in the database character set of the first
character of the
string.
Syntax:
ascii (string)
Ex:
SQL>
select ascii('a'), ascii('apple') from dual;
ASCII('A')
ASCII('APPLE')
------------
------------------
97
97
o)
CHR
This will return
the character having the binary equivalent to the string in either
the
database
character set or the national character set.
Syntax:
chr (number)
Ex:
SQL>
select chr(97) from dual;
CHR
-----
a
p)
SUBSTR
This will be
used to extract substrings.
Syntax:
substr (string,
start_chr_count [, no_of_chars])
Ex:
SQL>
select substr('computer',2), substr('computer',2,5),
substr('computer',3,7) from
dual;
SUBSTR(
SUBST SUBSTR
----------
------- --------
omputer
omput mputer
- If no_of_chars parameter is negative then it will display nothing.
- If both parameters except string are null or zeros then it will display nothing.
- If no_of_chars parameter is greater than the length of the string then it ignores and calculates based on the orginal string length.
- If start_chr_count is negative then it will extract the substring from right end.
1 2 3 4 5 6 7 8
C O M P U T E R
-8 -7 -6 -5 -4 -3 -2 -1
q)
INSTR
This will allows
you for searching through a string for set of characters.
Syntax:
instr (string,
search_str [, start_chr_count [, occurrence] ])
Ex:
SQL>
select instr('information','o',4,1), instr('information','o',4,2)
from dual;
INSTR('INFORMATION','O',4,1)
INSTR('INFORMATION','O',4,2)
------------------------------------
-------------------------------------
4
10
- If you are not specifying start_chr_count and occurrence then it will start search from
the beginning
and finds first occurrence only.
- If both parameters start_chr_count and occurrence are null, it will display nothing.
r)
DECODE
Decode will act
as value by value substitution.
For every value
of field, it will checks for a match in a series of if/then tests.
Syntax:
decode (value,
if1, then1, if2, then2, ……. else);
Ex:
SQL>
select sal, decode(sal,500,'Low',5000,'High','Medium') from emp;
SAL DECODE
-----
---------
500 Low
2500 Medium
2000 Medium
3500 Medium
3000 Medium
5000 High
4000 Medium
5000 High
1800 Medium
1200 Medium
2000 Medium
2700 Medium
2200 Medium
3200 Medium
SQL>
select decode(1,1,3), decode(1,2,3,4,4,6) from dual;
DECODE(1,1,3)
DECODE(1,2,3,4,4,6)
-----------------
------------------------
3
6
- If the number of parameters are odd and different then decode will display nothing.
- If the number of parameters are even and different then decode will display last
value.
- If all the parameters are null then decode will display nothing.
- If all the parameters are zeros then decode will display zero.
s)
GREATEST
This will give
the greatest string.
Syntax:
greatest (strng1,
string2, string3 … stringn)
Ex:
SQL>
select
greatest('a', 'b', 'c'), greatest('satish','srinu','saketh') from
dual;
GREAT
GREAT
-------
-------
c srinu
- If all the parameters are nulls then it will display nothing.
- If any of the parameters is null it will display nothing.
t)
LEAST
This will give
the least string.
Syntax:
greatest (strng1,
string2, string3 … stringn)
Ex:
SQL>
select
least('a', 'b', 'c'), least('satish','srinu','saketh') from dual;
LEAST
LEAST
-------
-------
a saketh
- If all the parameters are nulls then it will display nothing.
- If any of the parameters is null it will display nothing.
u)
COALESCE
This will gives
the first non-null string.
Syntax:
coalesce (strng1,
string2, string3 … stringn)
Ex:
SQL>
select coalesce('a','b','c'), coalesce(null,'a',null,'b') from dual;
COALESCE
COALESCE
-----------
-----------
a a
DATE
FUNCTIONS
- Sysdate
- Current_date
- Current_timestamp
- Systimestamp
- Localtimestamp
- Dbtimezone
- Sessiontimezone
- To_char
- To_date
- Add_months
- Months_between
- Next_day
- Last_day
- Extract
- Greatest
- Least
- Round
- Trunc
- New_time
- Coalesce
Oracle
default date format is DD-MON-YY.
We
can change the default format to our desired format by using the
following command.
SQL>
alter session set nls_date_format = ‘DD-MONTH-YYYY’;
But this will
expire once the session was closed.
a)
SYSDATE
This will give
the current date and time.
Ex:
SQL>
select sysdate from dual;
SYSDATE
-----------
24-DEC-06
b)
CURRENT_DATE
This will
returns the current date in the session’s timezone.
Ex:
SQL>
select current_date from dual;
CURRENT_DATE
------------------
24-DEC-06
c)
CURRENT_TIMESTAMP
This will
returns the current timestamp with the active time zone information.
Ex:
SQL>
select current_timestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
24-DEC-06
03.42.41.383369 AM +05:30
d)
SYSTIMESTAMP
This will
returns the system date, including fractional seconds and time zone
of the
database.
Ex:
SQL>
select systimestamp from dual;
SYSTIMESTAMP
---------------------------------------------------------------------------
24-DEC-06
03.49.31.830099 AM +05:30
e)
LOCALTIMESTAMP
This will
returns local timestamp in the active time zone information, with no
time zone
information
shown.
Ex:
SQL>
select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
24-DEC-06
03.44.18.502874 AM
f)
DBTIMEZONE
This will returns
the current database time zone in UTC format. (Coordinated Universal
Time)
Ex:
SQL>
select dbtimezone from dual;
DBTIMEZONE
---------------
-07:00
g)
SESSIONTIMEZONE
This will returns
the value of the current session’s time zone.
Ex:
SQL>
select sessiontimezone from dual;
SESSIONTIMEZONE
---------------------------------------------------------------------------
+05:30
h)
TO_CHAR
This will be used
to extract various date formats.
The available
date formats as follows.
Syntax:
to_char (date,
format)
DATE
FORMATS
D -- No
of days in week
DD -- No
of days in month
DDD -- No
of days in year
MM -- No
of month
MON -- Three
letter abbreviation of month
MONTH
-- Fully spelled out month
RM --
Roman numeral month
DY -- Three
letter abbreviated day
DAY -- Fully
spelled out day
Y -- Last
one digit of the year
YY -- Last
two digits of the year
YYY -- Last
three digits of the year
YYYY -- Full
four digit year
SYYYY -- Signed
year
I -- One
digit year from ISO standard
IY -- Two
digit year from ISO standard
IYY -- Three
digit year from ISO standard
IYYY -- Four
digit year from ISO standard
Y,
YYY -- Year
with comma
YEAR -- Fully
spelled out year
CC -- Century
Q -- No
of quarters
W -- No
of weeks in month
WW --
No of weeks in year
IW -- No
of weeks in year from ISO standard
HH -- Hours
MI -- Minutes
SS -- Seconds
FF -- Fractional
seconds
AM
or PM -- Displays
AM or PM depending upon time of day
A.M
or P.M -- Displays
A.M or P.M depending upon time of day
AD
or BC -- Displays
AD or BC depending upon the date
A.D
or B.C -- Displays
AD or BC depending upon the date
FM -- Prefix
to month or day, suppresses padding of month or day
TH -- Suffix
to a number
SP -- suffix
to a number to be spelled out
SPTH
-- Suffix combination of TH and SP to be both spelled out
THSP -- same
as SPTH
Ex:
SQL>
select to_char(sysdate,'dd month yyyy hh:mi:ss am dy') from dual;
TO_CHAR(SYSDATE,'DD
MONTH YYYYHH:MI
----------------------------------------------------
24
december 2006 02:03:23 pm sun
SQL>
select to_char(sysdate,'dd month year') from dual;
TO_CHAR(SYSDATE,'DDMONTHYEAR')
-------------------------------------------------------
24
december two thousand six
SQL>
select to_char(sysdate,'dd fmmonth year') from dual;
TO_CHAR(SYSDATE,'DD
FMMONTH YEAR')
-------------------------------------------------------
24
december two thousand six
SQL>
select to_char(sysdate,'ddth DDTH') from dual;
TO_CHAR(S
------------
24th
24TH
SQL>
select to_char(sysdate,'ddspth DDSPTH') from dual;
TO_CHAR(SYSDATE,'DDSPTHDDSPTH
------------------------------------------
twenty-fourth
TWENTY-FOURTH
SQL>
select to_char(sysdate,'ddsp Ddsp DDSP ') from dual;
TO_CHAR(SYSDATE,'DDSPDDSPDDSP')
------------------------------------------------
twenty-four
Twenty-Four TWENTY-FOUR
i)
TO_DATE
This will be used
to convert the string into data format.
Syntax:
to_date (date)
Ex:
SQL>
select to_char(to_date('24/dec/2006','dd/mon/yyyy'), 'dd * month *
day') from
dual;
TO_CHAR(TO_DATE('24/DEC/20
--------------------------
24
* december * Sunday
--
If you are not using to_char oracle will display output in default
date format.
j)
ADD_MONTHS
This will add the
specified months to the given date.
Syntax:
add_months (date,
no_of_months)
Ex:
SQL>
select add_months(to_date('11-jan-1990','dd-mon-yyyy'), 5) from dual;
ADD_MONTHS
----------------
11-JUN-90
SQL>
select add_months(to_date('11-jan-1990','dd-mon-yyyy'), -5) from
dual;
ADD_MONTH
---------------
11-AUG-89
- If no_of_months is zero then it will display the same date.
- If no_of_months is null then it will display nothing.
k)
MONTHS_BETWEEN
This will give
difference of months between two dates.
Syntax:
months_between (date1,
date2)
Ex:
SQL>
select months_between(to_date('11-aug-1990','dd-mon-yyyy'),
to_date('11-jan-
1990','dd-mon-yyyy'))
from dual;
MONTHS_BETWEEN(TO_DATE('11-AUG-1990','DD-MON-YYYY'),TO_DATE('11-JAN-1990','DD-MON-YYYY'))
-----------------------------------------------------------------------------------------------
7
SQL>
select months_between(to_date('11-jan-1990','dd-mon-yyyy'),
to_date('11-aug-
1990','dd-mon-yyyy'))
from dual;
MONTHS_BETWEEN(TO_DATE('11-JAN-1990','DD-MON-YYYY'),TO_DATE('11-AUG-1990','DD-MON-YYYY'))
-------------------------------------------------------------------------------------------------
-7
l)
NEXT_DAY
This will produce
next day of the given day from the specified date.
Syntax:
next_day (date,
day)
Ex:
SQL>
select next_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from
dual;
NEXT_DAY(
-------------
31-DEC-06
--
If the day parameter is null then it will display nothing.
m)
LAST_DAY
This will produce
last day of the given date.
Syntax:
last_day (date)
Ex:
SQL>
select last_day(to_date('24-dec-2006','dd-mon-yyyy'),'sun') from
dual;
LAST_DAY(
-------------
31-DEC-06
n)
EXTRACT
This is used to
extract a portion of the date value.
Syntax:
extract ((year | month | day | hour | minute | second), date)
Ex:
SQL>
select extract(year from sysdate) from dual;
EXTRACT(YEARFROMSYSDATE)
------------------------------------
2006
--
You can extract only one value at a time.
o)
GREATEST
This will give
the greatest date.
Syntax:
greatest (date1,
date2, date3 … daten)
Ex:
SQL>
select
greatest(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon-
yy'),to_date('11-apr-90','dd-mon-yy'))
from dual;
GREATEST(
-------------
11-APR-90
p)
LEAST
This will give
the least date.
Syntax:
least (date1,
date2, date3 … daten)
Ex:
SQL>
select
least(to_date('11-jan-90','dd-mon-yy'),to_date('11-mar-90','dd-mon-
yy'),to_date('11-apr-90','dd-mon-yy'))
from dual;
LEAST(
-------------
11-JAN-90
q)
ROUND
Round will rounds
the date to which it was equal to or greater than the given date.
Syntax:
round (date,
(day
| month | year))
If the second
parameter was year
then round will checks the month of the given date in the
following ranges.
JAN -- JUN
JUL
-- DEC
If the month
falls between JAN and JUN then it returns the first day of the
current year.
If the month
falls between JUL and DEC then it returns the first day of the next
year.
If the second
parameter was month
then round will checks the day of the given date in the
following ranges.
1 -- 15
16
-- 31
If the day falls
between 1 and 15 then it returns the first day of the current month.
If the day falls
between 16 and 31 then it returns the first day of the next month.
If the second
parameter was day
then round will checks the week day of the given date in
the following
ranges.
SUN -- WED
THU
-- SUN
If the week day
falls between SUN and WED then it returns the previous sunday.
If the weekday
falls between THU and SUN then it returns the next sunday.
- If the second parameter was null then it returns nothing.
- If the you are not specifying the second parameter then round will resets the time to the
begining
of the current day in case of user specified date.
- If the you are not specifying the second parameter then round will resets the time to the
begining
of the next day in case of sysdate.
Ex:
SQL>
select round(to_date('24-dec-04','dd-mon-yy'),'year'),
round(to_date('11-mar-
06','dd-mon-yy'),'year')
from dual;
ROUND(TO_
ROUND(TO_
------------
---------------
01-JAN-05
01-JAN-06
SQL>
select round(to_date('11-jan-04','dd-mon-yy'),'month'),
round(to_date('18-jan-
04','dd-mon-yy'),'month')
from dual;
ROUND(TO_
ROUND(TO_
-------------
---------------
01-JAN-04
01-FEB-04
SQL>
select round(to_date('26-dec-06','dd-mon-yy'),'day'),
round(to_date('29-dec-
06','dd-mon-yy'),'day')
from dual;
ROUND(TO_
ROUND(TO_
--------------
--------------
24-DEC-06
31-DEC-06
SQL>
select
to_char(round(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy
hh:mi:ss am')
from
dual;
TO_CHAR(ROUND(TO_DATE('
---------------------------------
24
dec 2006 12:00:00 am
r)
TRUNC
Trunc will chops
off the date to which it was equal to or less than the given date.
Syntax:
trunc (date,
(day
| month | year))
- If the second parameter was year then it always returns the first day of the current year.
- If the second parameter was month then it always returns the first day of the current month.
- If the second parameter was day then it always returns the previous sunday.
- If the second parameter was null then it returns nothing.
- If the you are not specifying the second parameter then trunk will resets the time to the
begining
of the current day.
Ex:
SQL>
select trunc(to_date('24-dec-04','dd-mon-yy'),'year'),
trunc(to_date('11-mar-
06','dd-mon-yy'),'year')
from dual;
TRUNC(TO_
TRUNC(TO_
-------------
--------------
01-JAN-04
01-JAN-06
SQL>
select trunc(to_date('11-jan-04','dd-mon-yy'),'month'),
trunc(to_date('18-jan-
04','dd-mon-yy'),'month')
from dual;
TRUNC(TO_
TRUNC(TO_
-------------
-------------
01-JAN-04
01-JAN-04
SQL>
select trunc(to_date('26-dec-06','dd-mon-yy'),'day'),
trunc(to_date('29-dec-06','dd-
mon-yy'),'day')
from dual;
TRUNC(TO_
TRUNC(TO_
-------------
--------------
24-DEC-06
24-DEC-06
SQL>
select
to_char(trunc(to_date('24-dec-06','dd-mon-yy')), 'dd mon yyyy
hh:mi:ss am')
from
dual;
TO_CHAR(TRUNC(TO_DATE('
---------------------------------
24
dec 2006 12:00:00 am
s)
NEW_TIME
This will give
the desired timezone’s date and time.
Syntax:
new_time (date,
current_timezone, desired_timezone)
Available
timezones are as follows.
TIMEZONES
AST/ADT -- Atlantic
standard/day light time
BST/BDT -- Bering
standard/day light time
CST/CDT -- Central
standard/day light time
EST/EDT -- Eastern
standard/day light time
GMT
-- Greenwich mean time
HST/HDT -- Alaska-Hawaii
standard/day light time
MST/MDT -- Mountain
standard/day light time
NST
-- Newfoundland standard time
PST/PDT -- Pacific
standard/day light time
YST/YDT -- Yukon
standard/day light time
Ex:
SQL>
select to_char(new_time(sysdate,'gmt','yst'),'dd mon yyyy hh:mi:ss
am') from dual;
TO_CHAR(NEW_TIME(SYSDAT
-----------------------------------
24
dec 2006 02:51:20 pm
SQL>
select to_char(new_time(sysdate,'gmt','est'),'dd mon yyyy hh:mi:ss
am') from dual;
TO_CHAR(NEW_TIME(SYSDAT
-----------------------
24
dec 2006 06:51:26 pm
t)
COALESCE
This will give
the first non-null date.
Syntax:
coalesce (date1,
date2, date3 … daten)
Ex:
SQL>
select coalesce('12-jan-90','13-jan-99'),
coalesce(null,'12-jan-90','23-mar-98',null)
from
dual;
COALESCE(
COALESCE(
-------------
------------
12-jan-90
12-jan-90
MISCELLANEOUS
FUNCTIONS
- Uid
- User
- Vsize
- Rank
- Dense_rank
a)
UID
This will
returns the integer value corresponding to the user currently logged
in.
Ex:
SQL>
select uid from dual;
UID
----------
319
b)
USER
This will
returns the login’s user name.
Ex:
SQL>
select user from dual;
USER
----------------
SAKETH
c)
VSIZE
This will
returns the number of bytes in the expression.
Ex:
SQL>
select vsize(123), vsize('computer'), vsize('12-jan-90') from dual;
VSIZE(123)
VSIZE('COMPUTER') VSIZE('12-JAN-90')
-------------
----------------------- ----------------------
3
8 9
d)
RANK
This will give
the non-sequential ranking.
Ex:
SQL>
select rownum,sal from (select sal from emp order by sal desc);
ROWNUM SAL
----------
----------
1 5000
2 3000
3 3000
4 2975
5 2850
6 2450
7 1600
8 1500
9 1300
10 1250
11 1250
12 1100
13 1000
14 950
15 800
SQL>
select rank(2975) within group(order by sal desc) from emp;
RANK(2975)WITHINGROUP(ORDERBYSALDESC)
---------------------------------------------------------
4
d)
DENSE_RANK
This will give
the sequential ranking.
Ex:
SQL>
select dense_rank(2975) within group(order by sal desc) from emp;
DENSE_RANK(2975)WITHINGROUP(ORDERBYSALDESC)
-----------------------------------------------------------------
3
CONVERSION
FUNCTIONS
- Bin_to_num
- Chartorowid
- Rowidtochar
- To_number
- To_char
- To_date
a)
BIN_TO_NUM
This will
convert the binary value to its numerical equivalent.
Syntax:
bin_to_num( binary_bits)
Ex:
SQL>
select bin_to_num(1,1,0) from dual;
BIN_TO_NUM(1,1,0)
------------------------
6
- If all the bits are zero then it produces zero.
- If all the bits are null then it produces an error.
b)
CHARTOROWID
This will
convert a character string to act like an internal oracle row
identifier or rowid.
c)
ROWIDTOCHAR
This will convert
an internal oracle row identifier or rowid to character string.
d)
TO_NUMBER
This will convert
a char or varchar to number.
e)
TO_CHAR
This will convert
a number or date to character string.
f)
TO_DATE
This will convert
a number, char or varchar to a date.
GROUP
FUNCTIONS
- Sum
- Avg
- Max
- Min
- Count
Group
functions will be applied on all the rows but produces single output.
a)
SUM
This will give
the sum of the values of the specified column.
Syntax:
sum (column)
Ex:
SQL>
select sum(sal) from emp;
SUM(SAL)
----------
38600
b)
AVG
This will give
the average of the values of the specified column.
Syntax:
avg (column)
Ex:
SQL>
select avg(sal) from emp;
AVG(SAL)
---------------
2757.14286
c)
MAX
This will give
the maximum of the values of the specified column.
Syntax:
max (column)
Ex:
SQL>
select max(sal) from emp;
MAX(SAL)
----------
5000
d)
MIN
This will give
the minimum of the values of the specified column.
Syntax:
min (column)
Ex:
SQL>
select min(sal) from emp;
MIN(SAL)
----------
500
e)
COUNT
This will give
the count of the values of the specified column.
Syntax:
count (column)
Ex:
SQL>
select
count(sal),count(*) from emp;
COUNT(SAL)
COUNT(*)
--------------
------------
14
14
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