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1. INSTR: returns the first-occurrence position of a character within a string
SQL>
SQL>
SQL> -- create demo table
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 Tester
8 rows selected.
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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 2
8 rows selected.
SQL>
SQL>
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SQL>
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SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
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2. Simple demo for INSTR function: returns a location within the string where search pattern begins
SQL> --INSTR: returns a location within the string where search pattern begins.
SQL>
SQL>
SQL> SELECT INSTR('This is a test','is') FROM dual;
INSTR('THISISATEST','IS')
-------------------------
3
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3. INSTR: Look for the second occurrence of 'is'
SQL>
SQL>
SQL> -- Look for the second occurrence of "is,"
SQL>
SQL> SELECT INSTR('This is a test','is',1,2) FROM dual;
INSTR('THISISATEST','IS',1,2)
-----------------------------
6
SQL>
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4. If search pattern is not in the string, the INSTR function returns 0
SQL>
SQL>
SQL> -- If search pattern is not in the string, the INSTR function returns 0:
SQL>
SQL> SELECT INSTR('This is a test','abc',1,2) FROM dual;
INSTR('THISISATEST','ABC',1,2)
------------------------------
0
5. Combine INSTR and SUBSTR together
SQL>
SQL>
SQL> SELECT SUBSTR('aaa, bb ccc', INSTR('aaa, bb ccc',', ')) FROM dual;
SUBSTR('
--------
, bb ccc
6. If the INSTR pattern is not found, then the entire string would be returned
SQL>
SQL> -- If the INSTR pattern is not found, then the entire string would be returned
SQL>
SQL> SELECT SUBSTR('aaa bbb c', INSTR('aaa bbb c','zonk')) FROM dual;
SUBSTR('A
---------
aaa bbb c