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This article mainly shows you the "mysql in the use of SQL statements need to pay attention to what", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "mysql in the use of SQL statements need to pay attention to what" this article.

1. Prohibit the use of select*, to get only the necessary fields.

2. Insert must specify a field and prohibit the use of insert into T values ().

3. Do not replace count (*) with count (column name) or count (constant).

4. Foreign keys and cascading must not be used, and all foreign key concepts must be solved in the application layer.

Example

Note: the direct comparison between `NULL` and any value is `NULL`. 1) the returned result of `NULLNULL` is `NULL`, not `false`. 2) the returned result of `NULL` is `NULL`, not `true`. 3) the returned result of `NULL1` is `NULL`, not `true`. These are all the contents of the article "what do you need to pay attention to when using SQL sentences in mysql?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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