Python MySQL: clean multiple foreign keys table
I am working with Python MySQL, and need to clean a table in my database that has 13328 rows.
I can not make a simple drop table, because this table is child and also father of other child foreign-keys linked on it. If I try drop table, the system forbidden me. The table is defined with ON UPDATE CASCADE, ON DELETE CASCADE and InnoDB; The primary_key index to that table is defined as
productID INT(6) NOT NULL AUTO_INCREMENT ...
PRIMARY KEY (productID,productNO)
Therefore, I just have to clean; this will automatically restore the table primary key index to 1 for the next input. Right?
This procedure worked fine for another table that was a father table, but not also a father and child table. But, for this table, which is child and father of other tables, I got stuck on it.
Here is the code - productID is my primary index key to this table:
def clean_tableProduct(self):
getMaxID_MySQLQuery = """SELECT MAX(productID)
FROM product;"""
cleanTabeMySQLQuery="""DELETE FROM product WHERE productID <=%s;"""
self.cursorMySQL.execute(getMaxID_MySQLQuery)
for row in self.cursorMySQL:
self.c开发者_运维知识库ursorMySQL.execute(cleanTabeMySQLQuery,(row[0],))
If I go to the MySQL console to check the processing results, it gets me:
mysql> SELECT MIN(productID)
FROM product;
4615748
mysql> SELECT MAX(productID)
FROM product;
4629075
If I run the same command on console to clean the table, it works:
mysql> DELETE FROM product WHERE productID <='4629075';
Query OK, 13328 rows affected (0.64 sec)
and shows me what I would normally expect.
However, if I go to Python function after having cleaned the table on console, and run the program again, and clean the table to restart the processing, it restarts the table index not with MIN:1, but instead 4629076.
Any suggestion?
All comments and suggestions are highly appreciated and welcome.
To remove all records from the table:
truncate table product
To reset next ID to 1:
ALTER TABLE product AUTO_INCREMENT = 1
or
SET insert_id;
INSERT INTO product ...;
(I haven't tested this. But i should work)
If you clean a table with truncate:
TRUNCATE TABLE product
As a side effect, that will reset the auto-increment counter. But you can also reset it manually:
ALTER TABLE product AUTO_INCREMENT = 1
Thanks a lot for all input and quick feedback. It did the trick!
Here is how it looks now:
def clean_tableProduct(self):
cleanTabeMySQLQuery = """TRUNCATE TABLE product;"""
self.cursorMySQL.execute(cleanTabeMySQLQuery)
setIndexMySQLQuery = """ALTER TABLE product AUTO_INCREMENT = 1;"""
self.cursorMySQL.execute(setIndexMySQLQuery)
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