CODEWITHSUNDEEP
pythonsqlformatting
matt
matt

Reputation: 753

How to turn a list of tuples into a string?

I have a list of tuples that I'm trying to incorporate into a SQL query but I can't figure out how to join them together without adding slashes. My like this:

list = [('val', 'val'), ('val', 'val'), ('val', 'val')]

If I turn each tuple into a string and try to join them with a a comma I'll get something like

' (\'val\, \'val\'), ...  '

What's the right way to do this, so I can get the list (without brackets) as a string?

I want to end up with::

q = """INSERT INTO test (feed,site) VALUES %s;"""  % string
string = " ('val', 'val'), ('val', 'val'), ('val', 'val') "

Upvotes: 2

Views: 2947

Answers (5)

matt
matt

Reputation: 753

Using MySQLdb, executemany does this.

cursor = db.cursor()
vals = [(1,2,3), (4,5,6), (7,8,9), (2,5,6)]
q = """INSERT INTO first (comments, feed, keyword) VALUES (%s, %s, %s)"""  
cursor.executemany(q, vals)

Upvotes: 2

Santa
Santa

Reputation: 11545

>>> L = [('val', 'val'), ('val', 'val'), ('val', 'val')]
>>> ','.join([repr(tup) for tup in L])
"('val', 'val'),('val', 'val'),('val', 'val')"

Though, as others have pointed out, doing this in a string placeholder meant to be sent to MySQL is rather unsafe.

Upvotes: 1

SilentGhost
SilentGhost

Reputation: 319621

You shouldn't be doing this. Have a look at definition of the functions that are used to execute your SQL statement. They'll take care of formatting. SQL statement itself should only contain placeholders.

For example, official docs for MySQLdb show how to do exactly what you want.

Upvotes: 1

Charles Beattie
Charles Beattie

Reputation: 5949

This:

",".join( x+","+y for x,y in lst )

will produce:

'val,val,val,val,val,val'

Upvotes: 1

YOU
YOU

Reputation: 123841

Like this?

>>> l=[('val', 'val'), ('val', 'val'), ('val', 'val')]
>>> ','.join(map(','.join,l))
'val,val,val,val,val,val'

Upvotes: 4

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