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Can table columns with a Foreign Key be NULL?

...NGINE=INNODB; CREATE TABLE child (id INT NULL, parent_id INT NULL, FOREIGN KEY (parent_id) REFERENCES parent(id) ) ENGINE=INNODB; INSERT INTO child (id, parent_id) VALUES (1, NULL); -- Query OK, 1 row affected (0.01 sec) INSERT INTO child (id, parent_id)...
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How do I split a multi-line string into multiple lines?

...df 2 sfasdf asdfgadfg 1 asfasdf sdfasdgf """ text = text.splitlines() rows_to_print = {} for line in range(len(text)): if text[line][0] == '1': rows_to_print = rows_to_print | {line, line + 1} rows_to_print = sorted(list(rows_to_print)) for i in rows_to_print: print(text[i]) ...
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How can I detect if this dictionary key exists in C#?

... Adam, that's really (not) helpful. What's the class hierarchy? What's the base type? – John Saunders May 13 '10 at 20:44 add a comment  |  ...
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StringUtils 字符串工具扩展:强大的文本处理工具集 · App Inventor 2 中文网

... 获取字符 CharAt(索引) 返回指定位置的字符(1-based 索引)。 返回值:指定位置的字符 获取字符Of CharAtOf(源文本, 索引) 返回指定文本中指定位置的字符(1-based 索引)。 返回值:指定位置的...
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Interface vs Abstract Class (general OO)

...fferences - Interfaces can't have any concrete implementations. Abstract base classes can. This allows you to provide concrete implementations there. This can allow an abstract base class to actually provide a more rigorous contract, wheras an interface really only describes how a class is used....
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What's the u prefix in a Python string?

... 3.0-3.2 will break. Because you need to decide if you care to use six.text_type() everywhere for the (hopefully miniscule) number of people still using 3.[012] - at least the information is there so you can choose. – dwanderson Aug 22 '18 at 0:31 ...
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How to secure MongoDB with username and password

...ata/db 2) Connect to the instance. mongo 3) Create the user. use some_db db.createUser( { user: "myNormalUser", pwd: "xyz123", roles: [ { role: "readWrite", db: "some_db" }, { role: "read", db: "some_other_db" } ] } ) 4) Stop the MongoDB instance and start it aga...
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continue processing php after sending http response

My script is called by server. From server I'll receive ID_OF_MESSAGE and TEXT_OF_MESSAGE . 12 Answers ...
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Form inside a form, is that alright? [duplicate]

...t" name="foo" form="saveForm" /> <input type="hidden" value="some_id" form="deleteForm" /> <input type="text" name="foo2" id="foo2" form="saveForm" value="success" /> <input type="submit" name="save" value="Save" form="saveForm" onclick="alert(document.getElementById('...
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Redirecting EC2 Elastic Load Balancer from HTTP to HTTPS

... RedirectConfig: Protocol: HTTPS StatusCode: HTTP_301 Port: 443 If you still use Classic Load Balancers, go with one of the NGINX configs described by the others. share | ...