ALTER TABLE Sqlite: how to check if a column exists before alter the table?
문제
I need to execute in python a SQL query that adds a new column, in sqlite3.
The problem is that sometimes it already exists. So previous to executing the query I need to check if the column already exists.
If it does, then I won't execute the query.
Is there a way in sqlite to do that? Or do I have to make it through a try-catch block in python code?
Thanks a lot in advance!
해결책
You can get a list of columns for a table via the following statement:
PRAGMA table_info('table_name');
More details on the pragma commands are availabel at the sqlite web site
다른 팁
IMO this
conn = sqlite3.connect(':memory:')
c = conn.cursor()
try:
c.execute('ALTER TABLE mytable ADD COLUMN newcolumn;')
except:
pass # handle the error
c.close()
is a better choice than constructing special case queries.
You can wrap the above code in a AddColumn(cursor, table, column) function so you can reuse it,
plus it'll make the code more readable.
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