提供两函数的基本用法，自己组合一下： 1. INSTR: returns the first-occurrence position of a character within a string SQL> create table Employee( 2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /Table created.SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values ('01','Jason', 'Martin', to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto', 'Programmer') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('02','Alison', 'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('03','James', 'Smith', to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('04','Celia', 'Rice', to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('05','Robert', 'Black', to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('06','Linda', 'Green', to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York', 'Tester') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('07','David', 'Larry', to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York', 'Manager') 3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester') 3 /1 row created.SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee 2 /ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION ---- ---------- ---------- --------- --------- ---------- ---------- --------------- 01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester8 rows selected.SQL> SQL> SQL> SQL> SQL> SQL> SQL> --INSTR: returns the first-occurrence position of a character within a string. SQL> --it returns a numeric value. SQL> SQL> --If it does not find the character value, it returns a 0. For example: SQL> SQL> SELECT First_name, INSTR(First_name,'a') AS INSTR FROM Employee;FIRST_NAME INSTR ---------- ---------- Jason 2 Alison 0 James 2 Celia 5 Robert 0 Linda 5 David 2 James 28 rows selected.2. Simple demo for INSTR function: returns a location within the string where search pattern begins SQL> SELECT INSTR('This is a test','is') FROM dual;INSTR('THISISATEST','IS') ------------------------- 3 3. INSTR: Look for the second occurrence of 'is' SQL> SELECT INSTR('This is a test','is',1,2) FROM dual;INSTR('THISISATEST','IS',1,2) ----------------------------- 6SQL> SQL> SQL>4. If search pattern is not in the string, the INSTR function returns 0 SQL> SELECT INSTR('This is a test','abc',1,2) FROM dual;INSTR('THISISATEST','ABC',1,2) ------------------------------ 05. Combine INSTR and SUBSTR together SQL> SELECT SUBSTR('aaa, bb ccc', INSTR('aaa, bb ccc',', ')) FROM dual;SUBSTR(' -------- , bb ccc6. If the INSTR pattern is not found, then the entire string would be returned SQL> SELECT SUBSTR('aaa bbb c', INSTR('aaa bbb c','zonk')) FROM dual;SUBSTR('A --------- aaa bbb c 1. Substr: retrieve a portion of the string SQL> -- Substr: retrieve a portion of the string. SQL> SQL> -- SUBSTR(string, start_at_position, number_of_characters_to_retrieve) SQL> SQL> SELECT SUBSTR('Mississippi', 5, 3) FROM dual;SUB --- iss2. SUBSTR: get the sub-string SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description) 2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester') 3 /1 row created.SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee 2 /ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION ---- ---------- ---------- --------- --------- ---------- ---------- --------------- 01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester8 rows selected.SQL> SQL> --Return the first initial and last name: SQL> SQL> SELECT SUBSTR(First_Name, 1, 1) , Last_Name FROM Employee;S LAST_NAME - ---------- J Martin A Mathews J Smith C Rice R Black L Green D Larry J Cat8 rows selected.SQL> SQL> SQL> -- clean the table SQL> drop table Employee 2 /Table dropped.SQL> SQL> SQL>3. Simple demo for SUBSTR function SQL> SQL> SQL> SELECT SUBSTR('My address is 123 Fourth St.',1,12) FROM dual;SUBSTR('MYAD ------------ My address iSQL>4. SUBSTR: from the right-hand side of original string SQL> SQL> -- SUBSTR: from the right-hand side of original string: SQL> SQL> SELECT SUBSTR('My address is 123 Fourth St.',-9,5) FROM dual;SUBST ----- ourthSQL> 5. SUBSTR and INSTR are used together SQL> SQL> -- SUBSTR and INSTR are used together SQL> SQL> SELECT SUBSTR('aaa, bb ccc', INSTR('aaa, bb ccc',', ')+2) FROM dual;SUBSTR ------ bb ccc
然后用subStr函数截取
1. INSTR: returns the first-occurrence position of a character within a string
SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 First_Name VARCHAR2(10 BYTE),
4 Last_Name VARCHAR2(10 BYTE),
5 Start_Date DATE,
6 End_Date DATE,
7 Salary Number(8,2),
8 City VARCHAR2(10 BYTE),
9 Description VARCHAR2(15 BYTE)
10 )
11 /Table created.SQL>
SQL> -- prepare data
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ('01','Jason', 'Martin', to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto', 'Programmer')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('02','Alison', 'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('03','James', 'Smith', to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('04','Celia', 'Rice', to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('05','Robert', 'Black', to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('06','Linda', 'Green', to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York', 'Tester')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('07','David', 'Larry', to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York', 'Manager')
3 /1 row created.SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
3 /1 row created.SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester8 rows selected.SQL>
SQL>
SQL>
SQL>
SQL>
SQL>
SQL> --INSTR: returns the first-occurrence position of a character within a string.
SQL> --it returns a numeric value.
SQL>
SQL> --If it does not find the character value, it returns a 0. For example:
SQL>
SQL> SELECT First_name, INSTR(First_name,'a') AS INSTR FROM Employee;FIRST_NAME INSTR
---------- ----------
Jason 2
Alison 0
James 2
Celia 5
Robert 0
Linda 5
David 2
James 28 rows selected.2. Simple demo for INSTR function: returns a location within the string where search pattern begins
SQL> SELECT INSTR('This is a test','is') FROM dual;INSTR('THISISATEST','IS')
-------------------------
3
3. INSTR: Look for the second occurrence of 'is'
SQL> SELECT INSTR('This is a test','is',1,2) FROM dual;INSTR('THISISATEST','IS',1,2)
-----------------------------
6SQL>
SQL>
SQL>4. If search pattern is not in the string, the INSTR function returns 0
SQL> SELECT INSTR('This is a test','abc',1,2) FROM dual;INSTR('THISISATEST','ABC',1,2)
------------------------------
05. Combine INSTR and SUBSTR together
SQL> SELECT SUBSTR('aaa, bb ccc', INSTR('aaa, bb ccc',', ')) FROM dual;SUBSTR('
--------
, bb ccc6. If the INSTR pattern is not found, then the entire string would be returned SQL> SELECT SUBSTR('aaa bbb c', INSTR('aaa bbb c','zonk')) FROM dual;SUBSTR('A
---------
aaa bbb c
1. Substr: retrieve a portion of the string
SQL> -- Substr: retrieve a portion of the string.
SQL>
SQL> -- SUBSTR(string, start_at_position, number_of_characters_to_retrieve)
SQL>
SQL> SELECT SUBSTR('Mississippi', 5, 3) FROM dual;SUB
---
iss2. SUBSTR: get the sub-string
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
3 /1 row created.SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester8 rows selected.SQL>
SQL> --Return the first initial and last name:
SQL>
SQL> SELECT SUBSTR(First_Name, 1, 1) , Last_Name FROM Employee;S LAST_NAME
- ----------
J Martin
A Mathews
J Smith
C Rice
R Black
L Green
D Larry
J Cat8 rows selected.SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /Table dropped.SQL>
SQL>
SQL>3. Simple demo for SUBSTR function
SQL>
SQL>
SQL> SELECT SUBSTR('My address is 123 Fourth St.',1,12) FROM dual;SUBSTR('MYAD
------------
My address iSQL>4. SUBSTR: from the right-hand side of original string
SQL>
SQL> -- SUBSTR: from the right-hand side of original string:
SQL>
SQL> SELECT SUBSTR('My address is 123 Fourth St.',-9,5) FROM dual;SUBST
-----
ourthSQL>
5. SUBSTR and INSTR are used together
SQL>
SQL> -- SUBSTR and INSTR are used together
SQL>
SQL> SELECT SUBSTR('aaa, bb ccc', INSTR('aaa, bb ccc',', ')+2) FROM dual;SUBSTR
------
bb ccc