如何查询每个字符的首字母？

Question

I have a table which has three columns: firstname, middlename, lastname. Now, when I type the first letter of each character, the query have to return correctly results.

Example: My database has one record:

When I type the input string as below (just only bold string), the returned results must have the record:

**n** or
**n k** or
**n p** or
**k p** or
**n k p**

I use SQLite, and at the currrent I do not have any idea. Could you give me a suggestion about this?

Answer 1

You could use wildcard % character to match any string/character and the LIKE statement as well.

For first name that starts with 'N' for example would be:

SELECT * FROM yourTable WHERE FirstName LIKE 'N%'

For first and last name it would be:

SELECT * FROM yourTable WHERE FirstName LIKE 'N%' or LastName LIKE 'P%'

Update :

And if you are not sure if the input is for first name, middle name or last name then you can do it on multiple fields, like:

SELECT * FROM yourTable 
WHERE FirstName LIKE 'N%' or MiddleName LIKE 'N%' or LastName LIKE 'N%'

And if there are more than one letter (say two) it would get a little crazier like:

SELECT * FROM yourTable 
WHERE FirstName LIKE 'N%' or MiddleName LIKE 'N%' or LastName LIKE 'N%'
or FirstName LIKE 'P%' or MiddleName LIKE 'P%' or LastName LIKE 'P%'

But using the solution above would not be good. So, it would be good that you allow the users to either:

1. Input letters for each name, that is, a letter for lastname and firstname and middlename if needed
2. Just input one letter (or of course a String) then search either from firstname, lastname and middlename.

For option number 1 you query would look like this:

SELECT * FROM yourTable 
WHERE FirstName LIKE 'N%' or MiddleName LIKE 'K%' or LastName LIKE 'P%'

For option number 2 you query would look like this:

SELECT * FROM yourTable 
WHERE FirstName LIKE 'N%' or MiddleName LIKE 'N%' or LastName LIKE 'N%'

or if it a String it would probably look like this:

SELECT * FROM yourTable 
WHERE FirstName LIKE 'Ngu%' or MiddleName LIKE 'Ngu%' or LastName LIKE 'Ngu%'

In other words take control of how the users input and give him/her little room for potential error not to mention confusion.