SqlAlchemy Programming Error when using raw SQL Like operator [duplicate] - sql

Question

This question already has an answer here:
CS50: LIKE operator, variable substitution with % expansion
(1 answer)
Closed 2 years ago.
I am trying to run a SQL query in my Flask application to search a database. However, I get an error when I run the query:
db.execute("SELECT * FROM books WHERE author LIKE '%:author%' ", {"author":query})
The resulting error is this (passed 'Tom' in my input):
sqlalchemy.exc.ProgrammingError: (psycopg2.errors.SyntaxError) syntax error at or near "Tom"
LINE 1: SELECT * FROM books WHERE author LIKE '%'Tom'%'
^
[SQL: SELECT * FROM books WHERE author LIKE '%%%(author)s%%' ]
[parameters: {'author': 'Tom'}]
(Background on this error at: http://sqlalche.me/e/f405)
I've tested the query with a hard coded value and it works fine. I would like to know what is causing the error and how to fix it.

Answer 1

You need string concatenation. Many SQL databases support concat() (and other have an equivalent function or operator, such as standard operator ||):
db.execute("SELECT * FROM books WHERE author LIKE CONCAT('%', :author, '%')", {"author":query})
Another option is to concatenate '%'s around your parameter in your application first, and then pass it to the query.