标签:password sql语句 重要 cursor text logs value from optional
pip install psycopg
以下是psycopg2的重要的的模块例程可以满足Python程序与PostgreSQL数据库的工作。
S.N. | API & 描述 |
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1 | psycopg2.connect(database="testdb", user="postgres", password="cohondob", host="127.0.0.1", port="5432") 这个API打开一个连接到PostgreSQL数据库。如果成功打开数据库时,它返回一个连接对象。 www.yiibai.com |
2 | connection.cursor() 该程序创建一个光标将用于整个数据库使用Python编程。 yiibai.com |
3 | cursor.execute(sql [, optional parameters]) 此例程执行SQL语句。可被参数化的SQL语句(即占位符,而不是SQL文字)。 psycopg2的模块支持占位符用%s标志 yiibai.com 例如:cursor.execute("insert into people values (%s, %s)", (who, age))
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4 | curosr.executemany(sql, seq_of_parameters) 该程序执行SQL命令对所有参数序列或序列中的sql映射。 www.yiibai.com |
5 | curosr.callproc(procname[, parameters]) 这个程序执行的存储数据库程序给定的名称。该程序预计为每一个参数,参数的顺序必须包含一个条目。
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6 | cursor.rowcount 这个只读属性,它返回数据库中的行的总数已修改,插入或删除最后 execute*().
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7 | connection.commit() 此方法提交当前事务。如果不调用这个方法,无论做了什么修改,自从上次调用commit()是不可见的,从其他的数据库连接。
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8 | connection.rollback() 此方法会回滚任何更改数据库自上次调用commit()方法。
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9 | connection.close() 此方法关闭数据库连接。请注意,这并不自动调用commit()。如果你只是关闭数据库连接而不调用commit()方法首先,那么所有更改将会丢失! www.yiibai.com |
10 | cursor.fetchone() 这种方法提取的查询结果集的下一行,返回一个序列,或者无当没有更多的数据是可用的。
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11 | cursor.fetchmany([size=cursor.arraysize]) 这个例程中取出下一个组的查询结果的行数,返回一个列表。当没有找到记录,返回空列表。该方法试图获取尽可能多的行所显示的大小参数。
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12 | cursor.fetchall() 这个例程获取所有查询结果(剩余)行,返回一个列表。空行时则返回空列表。 www.yiibai.com
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Python代码显示了如何连接到一个现有的数据库。如果数据库不存在,那么它就会被创建,最终将返回一个数据库对象
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully"
以下Python程序将使用以前创建的数据库中创建一个表:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully" cur = conn.cursor() cur.execute(‘‘‘CREATE TABLE COMPANY (ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL, ADDRESS CHAR(50), SALARY REAL);‘‘‘) print "Table created successfully" conn.commit() conn.close()
Python程序显示了我们如何创建表COMPANY 在上面的例子中创建表中的记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully" cur = conn.cursor() cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (1, ‘Paul‘, 32, ‘California‘, 20000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (2, ‘Allen‘, 25, ‘Texas‘, 15000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (3, ‘Teddy‘, 23, ‘Norway‘, 20000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) VALUES (4, ‘Mark‘, 25, ‘Rich-Mond ‘, 65000.00 )"); conn.commit() print "Records created successfully"; conn.close()
Python程序,显示如何获取并显示COMPANY 表在上面的例子中创建的记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully" cur = conn.cursor() cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print "ID = ", row[0] print "NAME = ", row[1] print "ADDRESS = ", row[2] print "SALARY = ", row[3], "\n" print "Operation done successfully"; conn.close()
当上述程序执行时,它会产生以下结果
Opened database successfully ID = 1 NAME = Paul ADDRESS = California SALARY = 20000.0 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000.0 ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000.0 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000.0 Operation done successfully
Python代码显示如何,我们可以使用UPDATE语句来更新记录,然后从COMPANY表获取并显示更新的记录
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully" cur = conn.cursor() cur.execute("UPDATE COMPANY set SALARY = 25000.00 where ID=1") conn.commit print "Total number of rows updated :", cur.rowcount cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print "ID = ", row[0] print "NAME = ", row[1] print "ADDRESS = ", row[2] print "SALARY = ", row[3], "\n" print "Operation done successfully"; conn.close()
Python代码显示了如何我们可以使用DELETE语句删除记录,然后获取并显示COMPANY 表剩余的记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print "Opened database successfully" cur = conn.cursor() cur.execute("DELETE from COMPANY where ID=2;") conn.commit print "Total number of rows deleted :", cur.rowcount cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print "ID = ", row[0] print "NAME = ", row[1] print "ADDRESS = ", row[2] print "SALARY = ", row[3], "\n" print "Operation done successfully"; conn.close()
标签:password sql语句 重要 cursor text logs value from optional
原文地址:http://www.cnblogs.com/Erick-L/p/7106816.html