Database - Introduction to SQL - Discussion

SQL wildcards can substitute for one or more characters when searching for data in a database.
SQL wildcards must be used with the SQL LIKE operator.
With SQL,
% A substitute for zero or more characters
_ A substitute for exactly one character

SELECT * FROM Persons
WHERE City LIKE 'sa%'
it will select the row where the city name starts with sa..

What is meant by wildcard can you explain clearly?

Can you explain with some more details?

Can you explain why Wildcard chars are used to replace any substring?

SQL wildcard('%') to find the entire search value or substring of the search value.It is like a grep command, which displays all results which matches that pattern.

For example if you have table student and want to display the student name ends with 'n' then the query will be:

SELECT * FROM STUDENT WHERE name LIKE '%n';

If you want to search name that have 'n' any where in the name:

SELECT * FROM STUDENT WHERE name LIKE '%n%';

If we consider we have emp table with ename as column.

If we want to get names which starts with Letter B then
select * from emp where ename like '%B%'

If we want to get names which starts with Letter B and ends with E then
select * from emp where ename like 'B%E%'

If we want to get names which ends with Letter B then
select * from emp where ename like 'E%'