Question

I’m having a hard time getting some sql in python to correctly go through MySQLdb. It’s pythons string formatting that is killing me.

My sql statement is using the LIKE keyword with wildcards. I’ve tried a number of different things in Python. The problem is once I get one of them working, there’s a line of code in MySQLdb that burps on string format.

Attempt 1:

“SELECT tag.userId, count(user.id) as totalRows FROM user INNER JOIN
tag ON user.id = tag.userId WHERE user.username LIKE ‘%%s%'” % (query)

This is a no go. I get value error:

ValueError: unsupported format character ”’ (0x27) at index 128

Attempt 2:

“SELECT tag.userId, count(user.id) as totalRows FROM user INNER JOIN
tag ON user.id = tag.userId WHERE user.username LIKE ‘\%%s\%'” %
(query)

I get the same result from attempt 1.

Attempt 3:

like = “LIKE ‘%” + str(query) + “%'” totalq = “SELECT tag.userId,
count(user.id) as totalRows FROM user INNER JOIN tag ON user.id =
tag.userId WHERE user.username ” + like

This correctly creates the totalq variable, but now when I go to run the query I get errors from MySQLdb:

File “build/bdist.macosx-10.6-universal/egg/MySQLdb/cursors.py”, line
158, in execute query = query % db.literal(args) TypeError: not enough
arguments for format string

Attempt 4:

like = “LIKE ‘\%” + str(query) + “\%'” totalq = “SELECT tag.userId,
count(user.id) as totalRows FROM user INNER JOIN tag ON user.id =
tag.userId WHERE user.username ” + like

This is the same output as attempt 3.

This all seems really strange. How can I use wildcards in sql statements with python?

Answer 1

It’s not about string formatting but the problem is how queries should be executed according to db operations requirements in Python (PEP 249)

try something like this:

sql = "SELECT column FROM table WHERE col1=%s AND col2=%s" 
params = (col1_value, col2_value)
cursor.execute(sql, params)

here are some examples for psycog2 where you have some explanations that should also be valid for mysql (mysqldb also follows PEP249 dba api guidance 2.0: here are examples for mysqldb)