Check out example codes for "oracle leftmost characters". It will help you in understanding the concepts better.
Code Example 1
-- For Oracle only -- syntax SUBSTR(<main-string>,1,<number-of-characters>) -- example SUBSTR('Useless stuff',1,10) -- OUTPUT: Useless st -- practical example SELECT SUBSTR('Useless stuff',1,10) FROM DUAL;
Code Example 2
/*Using SUBSTR in Oracle (Example from hackerrank.com): */ /*Simple select query...*/ SELECT DISTINCT city FROM station /*Using WHERE and SUBSTR to find (distinct) cities in station table that begin as well as end with a vowel.*/ WHERE SUBSTR(city,1,1) IN ('A','E','I','O','U') AND substr(city,-1) IN ('a','e','i','o','u'); /*Parameters for SUBSTR (Substring) in order are as follows: String, Start, Length.*/
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