当子字符串在字符串中时，从表中进行SQL SELECT

Question

Let's say I have a table named table1 in a sqlite3 database (via python) with two columns named 'id' and 'string' and here are the three entries in the table:

   id                string
  'a'               'google'
  'b'               'apple'
  'c'            'application' 

so let's say I want all the rows with 'app' in them, so how would i do that? I'm looking for something like this:

SELECT * FROM table1 WHERE 'app' in string

which would in theory return the last 2 rows....

Answer 1

You can use LIKE

SELECT * FROM table1 
WHERE string LIKE '%app%'

DEMO

UPDATE:

When you use a front wildcard ( LIKE '%app%' ), the performance will be roughly the same.

If you want string starting with app , then using LIKE 'app%' would be better. Here's the reason :-

The part before the first wildcard serves as an access predicate, that is, they limit the scanned index range. The remaining characters do not narrow the scanned index range—non-matching entries are just left out of the result.

Answer 2

尝试这个：

SELECT * FROM table1 WHERE string LIKE '%app%'

Answer 3

It's very simple. You need to use the LIKE '%' operator in SQL. It's for string matching.

Your query should be something like this:

SELECT * FROM table1
WHERE string LIKE '%app%'

Since you didn't mention whether 'app' should be positioned at the beginning of string or the end, I've wrapped the string 'app' around two '%', so that it will locate the 'app' string anywhere inside string.