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SUBSTRING() function

Substring() extracts a substring value from a specified string based on a designated start index and optional length.

Syntax

substring(expr,startIndex,length)

Arguments

Argument Description Data type Return value
expr Input string used to extract a substring    
startIndex Required int value for the starting index of the substring in the evaluated expression. Starts from zero.    
length Optional int value that represents the length of the substring to extract. Defaults to end of evaluated expr.    

Returns

Data type Value
string Returns a substring based on the startIndex value and optional length.

Examples

Substring of the string in a column

create table segments
    (_id id, segment string);

insert into segments(_id,segment)
    values (1,'green')

select _id, substring(segment,0,3) as substr from segments;
+-----+----------+
| _id | substr   |
+-----+----------+
|   1 | gre      |
+-----+----------+

Substring of a reversed string

create table segments
    (_id id, segment string);

insert into segments(_id,segment)
    values (1,'red')

select _id, substring(reverse(segment), 1) as substr from segments;
+-----+----------+
| _id | substr   |
+-----+----------+
|   1 | er       |
+-----+----------+