An Introduction to INSTR in SQL


INSTR functions look for sub-strings in a string, according to INSTR in SQL. The function returns an integer showing the location of the first character of this occurrence in the string. INSTR generates strings from the characters in the input character set. Instead of characters, INSTRB uses bytes.

INSTRC makes use of full Unicode characters. UCS2 code points are used in INSTR2. And INSTR4 makes use of the UCS4 code point system.

Important: The INSTR Function Locates a Substring Within a String.

According to INSTR in SQL, the position is a nonzero integer that indicates where the Oracle database searches for a character in a string. If the location is negative, Oracle counts backward from the string's end and then searches backward from the result.

An instance in SQL Occurrence is an integer that tells Oracle which occurrence of a string to look for. The event value must be positive.

Both location and event must resolve to an integer and be of datatype NUMBER, or any datatype that can be indirectly converted to NUMBER.

In INSTR in SQL, the default values for both location and occurrence are 1, which means Oracle looks for the first occurrence of the substring at the first character of the string.

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Indexes are seldom used when functions and operators are used. INSTR() is a prime example of this. A pattern with a constant pattern and no wildcards at the start is an exception.

According to INSTR in SQL, regardless of the value of posit, the return value is relative to the beginning of the series.


INSTR( string_data1, substring_value [, starting_index [, th_data_appearance ] ] )

INSTR(string_data1, string_data2);


SELECT INSTR('SQL World', 'World', 1,1) from dual;

The INSTR gives the nth occurrence from the position of the first character in the given string.



INSTRA() Parameter Arguments:

There are a few parameters that can be included in the INSTR() function. The parameters are:

  1. String
  2. Substring
  3. Start position
  4. Nth occurrence

String Argument

According to INSTR in SQL, the search string CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB are all valid string types.

The string argument is an original string or data. To find if any substring is present, you need to compare it with the original string.

Substring Argument

According to INSTR in SQL, a substring is a part of a string that is present in the original string. The substring in the string to look for and CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, or NCLOB are all valid substrings.

Starting Position

According to INSTR, in SQLIt's an option. The starting point for the search in the string. It defaults to 1 if it is not specified. The number one is the first position in the string. If the start position is negative, the INSTR function counts the back start position and the number of characters from the end of the string, before searching for the start position number of characters.

Nth Occurrence Argument

According to INSTR in SQL, it's an option. If this is the nth time a substring has appeared, it defaults to 1 if it is not specified. This may help you find how many times that substring may be present in the original string.

Return in INSTR()

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


SELECT INSTR('Welcome to SQL world', 'e') from dual;





SELECT INSTR('Welcome to SQL world', 'e', 1, 1) from dual;





SELECT INSTR('Welcome to SQL world', 'e', 1, 2) from dual;





SELECT INSTR('Welcome to SQL world', 'e', 1, 3) from dual;





SELECT INSTR('Welcome to SQL world', 'e', -3, 2) from dual;





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INSTR() Function With Table Data

According to INSTR in SQL, create a table with table name as in_data which includes the fields of str1 and str2 of varchardatatype.


create table in_data(str1 varchar(20),str2 varchar(26));


Table created.


Next, insert three records into the table in_data.


insert into in_data values('welcome to sql','sql');

insert into in_data values ('programming in c','cpp');

insert into in_data values('java programming','java');

select * from in_data;




welcome to sql


programming in c


java programming



Then you must try to do some operation on the table using the INSTR() function from SQL.


select INSTR(str1,str2,1,1) from in_data;

In the above example, it tried to find whether str2 is presented in the str1 column data from the table. If it is present, it will return the position number, otherwise, it will return zero as the output.


The output of the above-mentioned query is:






Another example is to find the given character is ‘a’ from the table data. Let consider the ‘a’ as a substring, and you need to compare this character with table data str1.


select INSTR(str1,'a',1,1) from in_data;


With the above example, let's check the string str1 compared with the ‘a’ character from the given table.






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SQL has numerous built-in functions that can be used for a variety of tasks. The case conversion of strings, in-string or substring operations, mathematical computations on numeric data, and date operations on date type values are all important capabilities of functions. SQL functions will optionally accept user arguments and must return a value.

Detects the first instance of a string or a character in another string. As a result, the INSTR() function keeps track of the location of any string/sub-initial/first string's occurrence in another string data meaning.

SQL Server has a number of SQL String Functions. They allow you to change the characters in a string individually, compare strings, search strings, extract substrings, and copy a string. These SQL String Functions may also be used to convert strings to lowercase or uppercase.

INSTR() helps to find if a substring is present in the original string. If a string is present, it gives the position of the substring in the original string from the indexed position. The number of occurrences of the substring is also returned as output. If the substring is not present in the original string, it returns zero.

While the SQL language has been around for a while, it continues to remain important today as organizations worldwide. SQL is regularly considered one of the most-demanded tech skills, and mastering it is essential to presenting a strong skill set.

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