SUBSTR and INSTR Character Function in Oracle #DOTC_MDB

 

Character Function SUBSTR and INSTR in Oracle

 

Hello Everyone ,

Today we will discuss about character Function SUBSTR and INSTR in Oracle SQL and its uses.

In SQL Character Functions mainly operate on Character data , Character Function can be used with columns having character data.

 SUBSTR :  SUBSTR functions allows you to extract a substring from a string. SUBSTR function returns a string value . If length is negative then SUBSTR function return a null value.

Note:  If the position is positive, then Oracle Database counts from the beginning of char to find the first character. If the position is negative, then Oracle counts backward from the end of char

Example of SUBSTR Function in Oracle SQL.

To show uses of SUBSTR with different parameter I will take example from dual table and existing table in a database.

To get the first 3 character we need to write below SQL query by using SUBSTR function to get the result.

// GET FIRST 3 CHARACTER FROM DUAL TABLE

 SELECT SUBSTR('BANGALORE', 1, 3) AS LOCATION FROM dual;

Below is the output of above query .

// TO GET LAST 3 CHARACTER (NEGATIVE START POSITION)

 SELECT SUBSTR('BANGALORE', -3) FROM dual;

Below is the output of above Query .

 

// GET THE VALUE FROM 4TH BELOW IS THE QUERY

 SELECT SUBSTR('BANGALORE', 4) AS LOCATION FROM dual;

 

BELOW IS THE OUTPUT OF ABOVE QUERY.

 

IN SAME MANNER WE CAN USE SUBSTR WITH NEGATIVE AND POSITIVE NUMBER TO SEE THE RESULT AS PER OUR REQUIREMENT.

 SELECT SUBSTR('BANGALORE', -5,3) AS LOCATION FROM dual;

Above query will return ALO

SELECT SUBSTR('BANGALORE', -8,2) AS LOCATION FROM dual;

Above query will return AN .

You can check SUBSTR in a table and for particular column you can get the result in same manner.

//Using SUBSTR in a base table

 SELECT SUBSTR(name, -5,2) from employee where emp_id in(9876,2000);

Below is the output of above query .

 

//Using SUBSTR to see the last character we need to use below query

 

SELECT SUBSTR(name, -1) from employee where emp_id in(9876,2000);

Output of above query is as below:

 

Try to use SUBSTR as per your data in a table.

 

INSTR :  INSTR function In SQL  returns the location of a substring in a string. INSTR function returns a numeric value. The first position in the string is 1.If substring is not found in string, then the INSTR function will return 0.

Note : INSTR function searches for a substring in a string and returns the position of the substring in a string.

Example of INSTR Function in SQL.

// USING INSTR TO SEE THE FIRST OCCURRENCE OF A BY USING BELOW QUERY

SELECT INSTR('MY NAME IS ABCDE', 'A') FROM DUAL;

SELECT INSTR('MY NAME IS ABCDE', 'A', 1, 1) FROM DUAL;

BOTH QUERIES WILL GIVE THE POSITION OF THE FIRST OCCURENCE OF CHARACTER A IN STRING AS NUMBER.

Output of above query is as below.

 

// Second occurrence of A by using below query

SELECT INSTR('MY NAME IS ABCDE', 'A', 1, 2) from dual

Output of above query is as below

 

 

// Third occurrence of A by using below query

SELECT INSTR('MY NAME IS ABCDE AND ', 'A', 1, 3) FROM DUAL

  Output of above query is as below:

 

// SECOND OCCURENCE FROM BACK COUNTING AND IT WILL GIVE RESULT AS 12

 

SELECT INSTR('MY NAME IS ABCDE AND ', 'A', -3, 2) FROM DUAL

Output of above query is as below:

//Using INSTR  Function in a base table

SELECT ENAME, INSTR(ENAME,'A') as NAME_POS

FROM EMP

Below is the output of above query.

 

Please go through this blog and practice Character Function SUBSTR and INSTR as per your requirement and for any questions please let me know.  In next blog I will come up with more character functions like TRIM,Length,LPAD,RPAD,TRIM etc.