Are MySQL databases case-sensitive?

Is MySQL database case-sensitive? Need specific code examples

When using the MySQL database, you sometimes encounter case sensitivity problems, that is, when querying, inserting, or updating data, different case situations may lead to different results. The MySQL database has a certain sensitivity in handling upper and lower case. Let's use specific code examples to deeply explore the sensitivity of the MySQL database to upper and lower case.

First, let’s create a simple database table for example demonstration:

CREATE TABLE users (
    id INT PRIMARY KEY,
    username VARCHAR(50)
);

INSERT INTO users (id, username) VALUES (1, 'JohnDoe');
INSERT INTO users (id, username) VALUES (2, 'janedoe');

The above code creates a table named users, which contains id and usernameTwo fields, and two records were inserted. Among them, the username field stores user names in different cases.

Next, we use code examples to observe how the MySQL database handles upper and lower case in different situations:

1. Query operation:

SELECT * FROM users WHERE username = 'JohnDoe';

In the above query statement, username uses mixed case. The MySQL database will perform case-sensitive matching and will only return results when the upper and lower case are exactly the same.

2. Insert operation:

INSERT INTO users (id, username) VALUES (3, 'johndoe');

In the insert operation, MySQL The database also performs case sensitivity checks. Although johndoe and JohnDoe may look similar, the database will insert them as different records due to the different case.

3. Update operation:

UPDATE users SET username = 'JaneDoe' WHERE id = 2;

In the update operation, it is case sensitive The same applies to sex. Even though janedoe is an existing record, due to the case mismatch, the update operation will be performed instead of being treated as duplicate data.

To sum up, the MySQL database is case-sensitive, and it is necessary to accurately match the case in the operation to obtain the correct results. When writing code, be sure to pay attention to case consistency to avoid problems caused by case sensitivity.

Through the above code examples, I hope readers can have a deeper understanding of the behavior of the MySQL database when handling upper and lower case, so as to perform database operations more accurately.

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