Oracle XSQL- P12 ppt

Table 8.62 Concat Results CONCAT_STR MANAGER-CLARK PRESIDENT-KING CLERK-MILLER Greatest The greatest function returns the alphanumerically greatest string in its parameter list.. Table 8

Trang 1

The chr function returns the character associated with the number in the database’s character set If USING NCHAR_CS is specified, it would use the database’s national character set

SELECT chr(65) SIXTY_FIVE ,

chr(65 USING NCHAR_CS) SIXTY_FIVE_NATIONAL FROM DUAL

Table 8.61 lists the results

Table 8.61 Chr Results

SIXTY_FIVE SIXTY_FIVE_NATIONAL

Concat

The concat function is equivalent to the || operator It merges two strings

SELECT concat(job,concat(‘-’,ename)) AS concat_str

FROM emp

WHERE deptno=10

Table 8.62 Concat Results

CONCAT_STR

MANAGER-CLARK

PRESIDENT-KING

CLERK-MILLER

Greatest

The greatest function returns the alphanumerically greatest string in its parameter list Numbers and dates can be intermixed in the parameter list, but dates use the default date mask It’s best to convert dates to strings first with the to_char function SELECT greatest(‘MAZE1’,ename,job,dname,’MAZE2’) AS greatest_str

FROM emp,dept

WHERE emp.deptno=dept.deptno

Trang 2

Table 8.63 lists the results.

Table 8.63 Greatest Result

GREATEST_STR

MAZE2

PRESIDENT

MILLER

Initcap

The initcap function capitalizes the first letter and lowercases all other letters

SELECT INITCAP(‘mIXeD CaSE’) AS initcap_str FROM DUAL

Table 8.64 Initcap Results

INITCAP_STR

Mixed case

Instr

The instr function, which can be translated to mean “in string,” searches the first string for the second string and returns the position You can specify where to start searching in the string and which occurrence to find

SELECT instr(‘tripper’,’rip’) AS rip_pos,

instr(‘tripper’,’trip’) AS trip_pos,

instr(‘tripper’,’per’) AS rep_pos,

instr(‘tripper’,’xxx’) AS xxx_pos

FROM dual

Table 8.65 Instr Simple Results

RIP_POS TRIP_POS REP_POS XXX_POS

Trang 3

SELECT instr(‘00-11-00-11-00-11’,’00’,2) AS start_1,

instr(‘00-11-00-11-00-11’,’00’,2,2) AS start_2_get_2 FROM dual

Table 8.66 Instr Position and Instance Results

START_1 START_2_GET_2

Instrb

The instrb function provides the same functionality of instr but returns the byte position This is advantageous when multibyte character sets are used It searches the first string for the second string and returns the position You can specify where to start searching in the string and which occurrence to find

SELECT instr(‘tripper’,’rip’) AS rip_pos,

instr(‘tripper’,’trip’) AS trip_pos, instr(‘tripper’,’per’) AS rep_pos, instr(‘tripper’,’xxx’) AS xxx_pos FROM dual

Table 8.67 Instr Simple Results

RIP_POS TRIP_POS REP_POS XXX_POS

SELECT instr(‘00-11-00-11-00-11’,’00’,2) AS start_1,

instr(‘00-11-00-11-00-11’,’00’,2,2) AS start_2_get_2 FROM dual

Table 8.68 Instr Position and Instance Results

START_1 START_2_GET_2

Trang 4

The least function returns the alphanumerically least string in its parameter list Numbers and dates can be intermixed in the parameter list, but dates use the default date mask It’s best to convert dates to strings first with the to_char function

SELECT least(‘DOH1’,ename,job,’DOH2’) AS least_str

FROM emp,dept

WHERE emp.deptno=dept.deptno

AND emp.deptno=10

Table 8.69 Least Results

LEAST_STR

CLARK

DOH1

CLERK

Length

The length function returns the number of characters in the string

SELECT dname,length(dname) AS length FROM dept

Table 8.70 Length Results

Trang 5

The lengthb function returns the number of bytes in the string This function is advantageous when multibyte character sets are used

SELECT dname,length(dname) AS length FROM dept

Table 8.71 Length Results

Lower

The lower function changes all letters to lowercase

SELECT lower(‘mIXeD CaSE’) AS lower_str FROM DUAL

INITCAP_STR

mixed case

Lpad

The lpad function guarantees the length of the string by prefixing characters or trun-cating By default, spaces are the pad character, but this can be specified

SELECT dname,

lpad(dname,8) AS space_pad, lpad(dname,8,’-’) AS dash_pad FROM dept

Trang 6

Table 8.73 Lpad Results

Ltrim

The ltrim trims characters from the left side By default, spaces are trimmed, but the strings to trim can be specified

SELECT ltrim(‘ string’) AS trim_str,

ltrim(‘####string’,’#’) AS single_char_trim,

ltrim(‘/**string’,’*/’) AS multi_char_trim

FROM dual

Table 8.74 Ltrim Results

TRIM_STR SINGLE_CHAR_TRIM MULTI_CHAR_TRIM

Nls_initcap

The nls_initcap function capitalizes the first letter and lowercases all other letters, based on the national character set

SELECT nls_initcap(‘mIXeD CaSE’) AS initcap_str FROM DUAL

INITCAP_STR

Trang 7

The nls_lower function changes all letters to lowercase, based on the national char-acter set

SELECT nls_lower(‘mIXeD CaSE’) AS lower_str FROM DUAL

INITCAP_STR

mixed case

Nls_upper

The nls_upper function changes all letters to lowercase

SELECT nls_upper(‘mIXeD CaSE’) AS upper_str FROM DUAL

Table 8.77 Upper Results

UPPER_STR

MIXED CASE

Nls_sort

The nls_sort function returns the byte sequence used to sort a string

Replace

The replace function replaces one substring with another in your string

SELECT replace(‘good or bad’,’or’,’and’) replace_str FROM dual

Trang 8

Table 8.78 Replace Results

REPLACE_STR

good and bad

Rpad

The rpad function guarantees the length of the string by suffixing characters or trun-cating By default, spaces are the pad character, but this character can be specified

SELECT dname,

rpad(dname,8) AS space_pad,

rpad(dname,8,’-’) AS dash_pad

FROM dept

Table 8.79 Rpad Results

Rtrim

The rtrim function trims characters from the right side By default, spaces are trimmed, but the characters to trim can be specified

SELECT ltrim(‘string ‘) AS trim_str,

ltrim(‘string####’,’#’) AS single_char_trim,

ltrim(‘string**/’,’/*’) AS multi_char_trim

FROM dual

Trang 9

TRIM_STR SINGLE_CHAR_TRIM MULTI_CHAR_TRIM

Soundex

Soundexis used to derive a phonetic pronunciation of the input string It is used to help in cases where a string may not be spelled exactly right The first letter is retained,

all vowels h and y are dropped, and the remaining letters are encoded.

SELECT soundex(dname) AS soundex_dname FROM dept

Table 8.81 lists the result

Table 8.81 Soundex Results

SOUNDEX_DNAME

A253

R262

S420

O163

Substr

The substr function returns a substring of the given string The second parameter, if positive, is the character position where your desired substring starts If negative, the position is an offset from the end of the string By default, the string ends at the end of the string If the third parameter is passed, it will specify the length of the string to extract

SELECT substr(dname,4) AS dname_4,

substr(dname,-4) AS dname_neg4, substr(dname,2,3) AS dname_2_3, substr(dname,-3,2) AS dname_neg3_2 FROM dept

Trang 10

Table 8.82 Substr Results

DNAME_4 DNAME_NEG4 DNAME_2_3

DNAME_NEG3_2

Substrb

The substrb function returns a substring of the given string where the parameters refer to a byte position It differs from substr only when a multibyte character set is used The second parameter, if positive, is the byte position where your desired sub-string starts If negative, the position is an offset from the end of the sub-string By default, the string ends at the end of the string If the third parameter is passed, it will specify the length of the string in bytes to extract

SELECT substrb(dname,4) AS dname_4,

substrb(dname,-4) AS dname_neg4,

substrb(dname,2,3) AS dname_2_3,

substrb(dname,-3,2) AS dname_neg3_2

FROM dept

Table 8.83 Substrb Results

DNAME_4 DNAME_NEG4 DNAME_2_3 DNAME_NEG3_2

Translate

The translate function changes one set of characters to another in the given string SELECT translate(dname,’AEIOU’,’12345’) AS trans_str

FROM dept

Trang 11

Table 8.84 Translate Results

TRANS_STR

1CC45NT3NG

R2S21RCH

S1L2S

4P2R1T34NS

Trim

The trimfunction trims characters from the left side By default, spaces are trimmed, but the strings to trim can be specified

SELECT trim(‘ string ‘) AS space_trim,

trim(‘*’ FROM ‘****string****’) AS trim_char trim(LEADING ‘*’ FROM ‘****string****’) AS lead_trim, trim(TRAILING ‘*’ FROM ‘****string****’) AS trail_trim FROM dual

SPACE_TRIM LEAD_TRIM TRAIL_TRIM TRIM_CHAR

string string string**** ****string

Upper

The upper function changes all letters to lowercase

SELECT upper(‘mIXeD CaSE’) AS upper_str FROM DUAL

Trang 12

Table 8.86 Upper Results

UPPER_STR

MIXED CASE

Date Functions

Date functions allow you to manipulate dates in SQL They are some of the most widely used functions in SQL With these functions you can get the current time, do arithmetic on dates, and convert between time zones The date formats used in this sec-tion were covered in the “Date Format Elements” secsec-tion

Add_months

The add_months function adds months to a particular date The date is kept unless it is too large for the new month In that case, the last date of the last month is used instead SELECT

to_date(‘01-31’,’MM-DD’) AS jan_str,

add_months(to_date(‘01-31’,’MM-DD’),1) AS feb_str,

add_months(to_date(‘01-31’,’MM-DD’),2) AS mar_str,

add_months(to_date(‘01-31’,’MM-DD’),3) AS apr_str

FROM dual

Table 8.87 Add_months Results

JAN_STR FEB_STR MAR_STR APR_STR

31-JAN-02 28-FEB-02 31-MAR-02 30-APR-02

Current_timestamp

The current_timestamp function returns the current timestamp from the table with

a TIMESTAMP WITH A TIMEZONE data type

SELECT to_char(current_timestamp,’YYYY-MM-DD HH24:MM:SS.FF’) AS date_str

FROM dual

Trang 13

Table 8.88 Sysdate Results

DATE_STR

2002-05-19 01:05:00.000001

Dbtimezone

The dbtimezone function returns the timezone of the database:

SELECT dbtimezone AS tz FROM dual

Table 8.89 Dbtimezone Results

TZ

-5:00

Extract

The extract function extracts the specified part (year, month, day, hour, minute, second, timezone_hour, timezone_minute, timezone_region, and timezone_abbr) from the date

SELECT hiredate, extract(YEAR FROM hiredate) AS year

FROM emp

WHERE deptno=10

Table 8.90 Extract Results

Trang 14

The greatest function returns the greatest number in its parameter list Numbers and dates can be intermixed in the parameter list, but dates use the default date mask It’s best to convert dates to strings first with the to_char function

SELECT

greatest(hiredate,to_date(‘16-NOV-1981’,’DD-MON-YYYY’)) AS

greatest_date

FROM emp WHERE deptno=10;

Table 8.91 Greatest Results

GREATEST_DATE

16-NOV-81

17-NOV-81

23-JAN-82

Last_day

The last_day function returns the last day of the month in which the specified date falls

SELECT hiredate,last_day(hiredate) AS last

FROM emp

WHERE deptno=10

Table 8.92 Last_day Results

Trang 15

The greatest function returns the least number in its parameter list Numbers and dates can be intermixed in the parameter list, but dates use the default date mask It’s best to convert dates to strings first with the to_char function

SELECT

least(hiredate,to_date(‘16-NOV-1981’,’DD-MON-YYYY’)) AS least_date FROM emp WHERE deptno=10;

Table 8.93 Least Results

LEAST_DATE

09-JUN-81

16-NOV-81

Local_timestamp

The local_timestamp function returns the timestamp in the local timezone as a timestamp data type This function is sometimes preferable to current_timestamp, because the latter returns the timestamp with the timezonedata type

SELECT to_char(localtimestamp,’YYYY-MM-DD HH24:MI:SSXFF’) AS time

FROM dual

Table 8.94 Local_timestamp Results

TIME

2002-05-19 01:34:21.000001

Months_between

The months_between function returns the number of months between two dates Integers are only returned if both dates have the same day of the month or if both dates fall on the last day of their respective months A negative number is returned if the first argument precedes the second argument You can use the abs function to always get a positive number

Trang 16

SELECT months_between(to_date(‘01-16’,’MM-DD’),to_date(‘08.16’,’MM-DD’))

AS btwn_1,

months_between(to_date(‘08.16’,’MM-DD’),to_date(‘01-16’,’MM-DD’))

AS btwn_2,

months_between(to_date(‘01-16’,’MM-DD’),to_date(‘08.31’,’MM-DD’))

AS btwn_3,

months_between(to_date(‘02-28’,’MM-DD’),to_date(‘08.31’,’MM-DD’))

AS btwn_4

FROM dual;

Table 8.95 Months_between Results

New_time

The new_time function converts a time from one timezone to another

SELECT to_char(

new_time(to_date(‘08:00’,’HH24:MI’),’EST’,’GMT’),

‘HH24:MI’) AS new_time_str

FROM dual

Table 8.96 New_time Results

NEW_TIME_STR

13:00

Next_day

The next_day function returns the date after a given date that falls on the given day

of the week If the given date falls on the given day of the week, the date one week hence is returned This can be fixed by always subtracting 1 from the date

SELECT ename,

deptno,

to_char(hiredate,’DY, MON-DD’) AS hire_date,

next_day(hiredate,’Fri’) AS next_fri_1,

Trang 17

FROM emp

WHERE deptno=30

Table 8.97 Next_day Results

HIRE_DATE NEXT_FRI_1 NEXT_FRI_2

ALLEN FRI, FEB-20 27-FEB-81 20-FEB-81

WARD SUN, FEB-22 27-FEB-81 27-FEB-81

MARTIN MON, SEP-28 02-OCT-81 02-OCT-81

BLAKE FRI, MAY-01 08-MAY-81 01-MAY-81

TURNER TUE, SEP-08 11-SEP-81 11-SEP-81

JAMES THU, DEC-03 04-DEC-81 04-DEC-81

Numtodsinterval

The numtodsinterval function converts the parameter to an interval day to second interval The string argument specifies the unit and can be one of SECOND, MINUTE, HOUR, or DAY

SELECT hiredate,

hiredate+numtodsinterval(100,’day’) AS days, hiredate+numtodsinterval(1000,’hour’) AS hours, hiredate+numtodsinterval(10000,’minute’) AS minutes, hiredate+numtodsinterval(100000,’second’) AS seconds FROM emp

WHERE deptno=10

Table 8.98 Numtodsinterval Results

09-JUN-81 17-SEP-81 20-JUL-81 15-JUN-81 10-JUN-81

17-NOV-81 25-FEB-82 28-DEC-81 23-NOV-81 18-NOV-81

23-JAN-82 03-MAY-82 5-MAR-82 29-JAN-82 24-JAN-82

Trang 18

The numtoyminterval function converts the parameter and interval year to month interval The string argument specifies the unit and can be either MONTH or YEAR

SELECT hiredate,

hiredate+numtoyminterval(1,’year’) AS years,

hiredate+numtoyminterval(10,’month’) AS months

FROM emp

WHERE deptno=10

Table 8.99 Numtoyminterval Results

09-JUN-81 09-JUN-82 09-APR-82

17-NOV-81 17-NOV-82 17-SEP-82

23-JAN-82 23-JAN-83 23-NOV-82

Round

The round function rounds a datetime value to the nearest unit specified by the for-mat By default, the date is rounded to the precision of the default forfor-mat

SELECT to_char(round(sysdate,’HH’),’YYYY-MM-DD HH24:MI’) AS hour,

to_char(round(sysdate,’MM’), ‘YYYY-MM-DD HH24:MI’) AS month,

to_char(round(sysdate,’YYYY’), ‘YYYY-MM-DD HH24:MI’) AS year,

to_char(round(sysdate,’CC’), ‘YYYY-MM-DD HH24:MI’) AS century

FROM dual

Table 8.100 Round Results

2002-05-18 2002-06-01 2002-01-01 2001-01-01

Định dạng
Số trang	20
Dung lượng	193,67 KB