Update database with multiple SQL Statments

Question

I am using mysql connector.Python 1.0.9 downloaded from MySQL site.

I have a sample table here

DROP TABLE IF EXISTS my_table; 
CREATE TABLE my_table
(id INT NOT NULL AUTO_INCREMENT UNIQUE,
Shot VARCHAR(4),
sec varchar(5),
lay VARCHAR(15) NOT NULL,
lay_status VARCHAR(15) NOT NULL,
blk VARCHAR(10) NOT NULL,
blk_status VARCHAR(15) NOT NULL,
pri VARCHAR(10) NOT NULL,
pri_status VARCHAR(15) NOT NULL,
ani VARCHAR(10) NOT NULL,
ani_status VARCHAR(15) NOT NULL,
status VARCHAR(5)
);

INSERT INTO my_table VALUES
(1,'SH01','3','1863','yes','1863','yes','P4645','yes','P4557','yes','Over'),
(2,'SH02','2.5','1863','yes','P4645','no','P4557','yes','1863','no','Over'),
(3,'SH03','0.5','P4645','yes','P4557','yes','1863','yes','1863','yes','WIP'),
(4,'SH04','1.25','1863','no','P4645','no','P4557','yes','1863','yes','RTK'),
(5,'SH05','1','1863','yes','1863','yes','P4645','yes','P4557','yes','WIP'),
(6,'SH06','6','P4557','yes','P4645','yes','P4645','yes','P4557','yes','WIP');

i am able to execute a single SQL statment as below.

import mysql.connector

cnx = mysql.connector.connect(user='scott', database='test')
cursor = cnx.cursor()

SQL = '''
        update my_table 
        set 
        LAY = 'P6682'
        , BLK = 'P6682'
        , ANI = 'P6682'
        where
        Shot = 'SH01';
      '''

cursor.execute(SQL)

and everything is fine and database gets updated correctly.

now when i am trying to update the database with multiple statements as below

import mysql.connector

cnx = mysql.connector.connect(user='scott', database='test')
cursor = cnx.cursor()

SQL = '''
    update my_table 
    set 
    LAY = 'P6682'
    , BLK = 'P6682'
    , ANI = 'P6682'
    where
    Shot = 'SH01';

    update my_table 
    set 
    LAY = '1863'
    , BLK = '1863'
    , ANI = '1863'
    where
    Shot = 'SH02'
'''

cursor.execute(SQL)
cnx.commit()
cur.close()
cnx.close()
cnx.disconnect()

I get below trackback error

Traceback (most recent call last):
  File "Test_Module.py", line 24, in 
  File "C:\Python26\Lib\site-packages\mysql\connector\cursor.py", line 396, in execute
    "Use multi=True when executing multiple statements")
InterfaceError: Use multi=True when executing multiple statements

I update my command as below

cursor.execute(SQL,multi = True)

cnx.commit()
cur.close()
cnx.close()
cnx.disconnect()

Now i dont get any error/Traceback. But the database is not getting updated.

Can any one tell me where am i doing wrong.

Answer 1

At-last after a long research on docs and help. I could able to solve the issue.

Using a for loop at cursor.execute with multi=True worked. I don't know why we need to loop through.

for result in cursor.execute(SQL, multi=True):
    pass

Without loop just cursor.execute(SQL, multi=True) did not do any changes in the database.

import mysql.connector

cnx = mysql.connector.connect(user='scott', database='test')
cursor = cnx.cursor()

SQL = '''
    update my_table 
    set 
    LAY = 'P6682'
    , BLK = 'P6682'
    , ANI = 'P6682'
    where
    Shot = 'SH01';

    update my_table 
    set 
    LAY = '1863'
    , BLK = '1863'
    , ANI = '1863'
    where
    Shot = 'SH02'
'''

for result in cursor.execute(SQL, multi=True):
    pass

cnx.commit()
cur.close()
cnx.close()
cnx.disconnect()

Answer 2

Looking at the MySQL docs

If multi is set to True, execute() is able to execute multiple statements specified in the operation string. It returns an iterator that enables processing the result of each statement. However, using parameters does not work well in this case, and it is usually a good idea to execute each statement on its own.

so setting multi=True returns an iterator and if you just want to loop through each statement, the other solution offered works well:

for result in cursor.execute(SQL, multi=True):
    pass

Answer 3

Did you miss somekind of commit

cnx.commit()

MySQL reference