游标(cursor):系统为用户开通的一个数据缓冲区,用于存放SQL语句执行结果。用户使用的sql会逐一的在游标中获取记录,并赋值给主变量,交由Python进一步处理,一组主变量只能存放一条记录。
例题:
from T1 importconnect_mysql#----主函数
if __name__ == '__main__':
sql= 'select * from test;'cnn=connect_mysql()
cur=cnn.cursor()#print (dir(cur))
try:
cur.execute(sql)#----fetchone 取结果的一行
result=cur.fetchone()print(result)#----fetchmany(nu)根据nu数字取结果行数
result1=cur.fetchmany(3)print(result1)#----fetchall()取全部结果
result2=cur.fetchall( )#print ('22222222')
print(result2)
cur.close()exceptException as e:
cnn.rollback()raiseefinally:
cnn.close()
执行结果:
C:\Python27\python.exe E:/untitled/mysql/T2.py
(100L,)
((200L,), (300L,), (300L,))
((40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,))
Process finished with exit code 0
图中语句依次执行由于数据只有四条,并且三者语句一起执行,所以执行ftechone取走一条,执行fetchmany(3)取走三条,剩下以为空所以fetchall()只能取空。
执行多条语句:
from T1 import connect_mysql
#----主函数
if __name__ == '__main__':
sql= 'select * from test;'
sq11='insert into test(id) VALUES (%s);'
#----将函数组合成多个list
Lis=[]
for i in xrange(40,50):----此处表示批量执行语句的格式,为sql语句+参数,将一列参数(类型为list)逐个传入sql1中。
Lis.append([str(i)])
# print (Lis)
cnn=connect_mysql()
cur= cnn.cursor()
try:
cur.executemany(sq11,Lis) -----注意二者的执行顺序应该先插入后再查询否则查询结果为空。
cur.execute(sql)
#----fetchall()取全部结果
result2=cur.fetchall( )
print (result2)
cur.close()
cnn.commit()-------执行语句后需要执行提交否则数据库内无法生效。
except Exception as e:
cnn.rollback()
raise e
finally:
cnn.close()
执行结果:
C:\Python27\python.exe E:/untitled/mysql/T2.py
((100L,), (200L,), (300L,), (300L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,), (40L,), (41L,), (42L,), (43L,), (44L,), (45L,), (46L,), (47L,), (48L,), (49L,))
Process finished with exit code 0