mysql character escape

MySQL is a widely used open source relational database management system. When using MySQL, we may encounter situations where characters need to be escaped. For example, when executing query statements, special characters must be escaped to ensure the correctness of the query results. This article will introduce how to escape characters in MySQL.

Common escape characters in MySQL include single quotation mark ('), double quotation mark ("), backslash (), and some special characters, such as percent sign (%) and underscore (_). These characters have special meaning in MySQL. If not escaped, it may lead to incorrect query results or security issues such as SQL injection.

In MySQL, escaping characters can be done using backslashes Escape. Specifically, if you want to use single quotes in the query statement, you need to add a backslash in front of the single quotes, as shown below:

SELECT * FROM my_table WHERE my_column = 'I'm a student';

In this way, you can correctly query the string containing single quotes String. Similarly, if you want to use double quotes, you also need to escape them:

SELECT * FROM my_table WHERE my_column = "The book is called "The Great Gatsby"";

In MySQL, backslashes can also be used to escape special characters. For example, if you want to query all items containing percentages For strings with symbols, you can use the following query statement:

SELECT * FROM my_table WHERE my_column LIKE '%%%';

This way you can correctly match the percent sign in the string.

In addition to using backslash escape characters, MySQL Some built-in functions are also provided for character escaping. For example, you can use the double vertical bar (||) operator to concatenate strings, and use the function CONCAT_WS() to automatically escape characters, as shown below:

SELECT CONCAT_WS(' ', 'I', 'am', 'a', 'student') AS sentence;

This query statement will return a string containing spaces, in which words have been properly escaped.

In addition to using escape characters to escape strings, you can also use parameterization The query avoids the security issue of string injection. Parameterized query is a method of using placeholders instead of actual values, which can prevent malicious users from attacking the database by injecting malicious strings. For example, you can use the following parameterized query to query the query containing the specified String of words:

SELECT * FROM my_table WHERE my_column LIKE CONCAT('%', ?, '%');

The question mark here represents a placeholder that can be dynamically replaced with the actual value during query. Using parameterized queries can greatly improve the security of the application.

In short, character escaping is a very important concept in MySQL. Understanding how to escape characters correctly can avoid query result errors, SQL injection and other security issues. In actual development, it is recommended to use parameterized queries as much as possible to ensure Query security.

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