提问人:Orxan Mirzəyev 提问时间:11/17/2023 最后编辑:John GordonOrxan Mirzəyev 更新时间:11/17/2023 访问量:46
如何在where子句中使用变量if条件?
How can I use a variable if condition inside the where clause?
问:
我使用 Python 和 SQLite 我想在字符串查询中使用局部变量条件。 我该怎么做,如下所示?
A = 0
B = 0
"""Select * from TABLE where (TABLE.FIELD = ? OR A = 0) AND (TABLE.FIELD = ? OR B = 0) ..... """
${A} == 0 和 ${B} == 0
答:
5赞
ali
11/17/2023
#1
在 Python 的 SQLite 中,您可以通过使用该方法并将变量作为元组传递来在子句中使用变量。但是,您的查询似乎涉及直接字段比较和可变条件。为此,您可能需要根据 A 和 B 的值动态构造查询。WHERE
execute()
import sqlite3
# Assuming A and B are variables
A = 0
B = 0
# Your base query
base_query = "SELECT * FROM TABLE WHERE"
# Conditions based on A and B values
conditions = []
parameters = []
# Condition for TABLE.FIELD = ? or A = 0
if A == 0:
conditions.append("(TABLE.FIELD = ? OR A = 0)")
parameters.append(some_value_for_FIELD) # Replace some_value_for_FIELD with your desired value
else:
conditions.append("TABLE.FIELD = ?")
parameters.append(some_other_value_for_FIELD) # Replace some_other_value_for_FIELD with another value
# Condition for TABLE.FIELD = ? or B = 0
if B == 0:
conditions.append("(TABLE.FIELD = ? OR B = 0)")
parameters.append(some_value_for_FIELD) # Replace some_value_for_FIELD with your desired value
else:
conditions.append("TABLE.FIELD = ?")
parameters.append(some_other_value_for_FIELD) # Replace some_other_value_for_FIELD with another value
# Joining conditions
full_query = base_query + " AND ".join(conditions)
# Establish connection and execute query
conn = sqlite3.connect('your_database.db')
cursor = conn.cursor()
cursor.execute(full_query, tuple(parameters))
# Fetch results
results = cursor.fetchall()
# Process results
for row in results:
# Do something with each row
print(row)
# Close the connection
conn.close()
根据您的特定用例,将 和 替换为所需的字段值。该示例根据A和B的值动态构造查询,并使用参数来防止SQL注入漏洞。some_value_for_FIELD
some_other_value_for_FIELD
TABLE.FIELD
评论
0赞
Orxan Mirzəyev
11/17/2023
非常非常感谢:)这不是最简单的方法吗?
评论
TABLE.FIELD
A
B