Question

我有一个包含三列的SQLite数据库表：order_id，item，quantity。每行都有一个order_id，一个项目和一个数量。

我正在尝试编写一个查找包含两个不同项（item1和item2）的订单的查询，以便我的输出看起来像这样：

order_id | item   | quantity
---------------------------
1234     | item1  |  7
---------------------------
1234     | item2  |  2
---------------------------
5678     | item1  |  5
---------------------------
5678     | item2  |  3

这是我到目前为止拼凑的代码：

cur.execute("SELECT * FROM Orders WHERE term=? AND term=?", [("item1"), ("item2")])

如果我使用OR语句，我会得到我期望的结果。我逻辑上理解为什么这不适用于AND，但是我无法弄清楚能使它工作的SQL语句。

Answer 1

您需要在Order上内联两个order_id表：

sql = '''SELECT o1.*, o2.*
FROM Orders as o1
INNER JOIN Orders as o2
ON o1.order_id = o2.order_id
WHERE o1.item = ?
    AND o2.item = ?'''

args = ("item1", "item2")
cur.execute(sql, args)

Answer 2

如果您想要所有包含item1和item2的订单，那么您需要自我加入和输出尝试

Select * From (    
select * from sometable I1
    inner join someTable i2 on I1.Order_Id = I2.Order_ID
    Where I1.item = 'item1' and I2.Item = 'item2'
    union  
    select * from sometable I2
    inner join someTable i1 on I2.Order_Id = I1.Order_ID
    Where I2.item = 'item2' and I1.Item = 'item1'
) both 
order by Order_id,item, quantity desc

Answer 3

这是另一种方法，使用count子查询和内连接。

# setup
import sqlite3
cnxn = sqlite3.connect(':memory:')
cursor = cnxn.cursor()
cursor.execute("CREATE TABLE Orders (order_id integer, item text, quantity integer)")
cursor.executemany("""
    INSERT INTO Orders (order_id, item, quantity) 
    VALUES (?, ?, ?)
""", [(1234, 'item1', 7), (1234, 'item2', 4), (4567, 'item1', 3)])

# answer
cursor.execute("""
    SELECT Orders.order_id, Orders.item, Orders.quantity 
    FROM Orders 
    INNER JOIN (SELECT order_id, COUNT(order_id) AS cnt FROM Orders GROUP BY order_id) Orders_count
    ON Orders.order_id = Orders_count.order_id
    WHERE Orders_count.cnt > 1
""")

results = cursor.fetchall()
# [(1234, u'item1', 7), (1234, u'item2', 4)]
cnxn.close()

用Python在SQLite中构造一个AND语句

3 个答案: