How to Execute a SELECT Query with an IN Clause Using MySQLdb?

Executing "SELECT ... WHERE ... IN ..." using MySQLdb

When attempting to execute a SELECT query with an IN clause using MySQLdb, users may encounter issues where no rows are returned despite the query working as expected from the mysql command-line. This can occur due to unnecessary quotes being placed around the IN values.

To overcome this issue, manual construction of the query parameters is required. In both Python 2 and 3, a comma-separated string of placeholders (%s) can be generated from the list of IN values. The query can then be formatted using this string and executed with the original list of values.

For Python 3:

<code class="python">args=['A', 'C']
sql='SELECT fooid FROM foo WHERE bar IN (%s)' 
in_p=', '.join(list(map(lambda x: '%s', args)))
sql = sql % in_p
cursor.execute(sql, args)</code>

For Python 2:

<code class="python">args=['A', 'C']
sql='SELECT fooid FROM foo WHERE bar IN (%s)' 
in_p=', '.join(map(lambda x: '%s', args))
sql = sql % in_p
cursor.execute(sql, args)</code>

By following this approach, the SQL query will be correctly formatted with the desired IN values, resolving the issue where no rows were returned previously.

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