Detailed description of the case setting problem in MySQL

MySQL case settings

MySQL is an open source relational database management system that is widely used in Internet applications, data warehouses, data storage and other fields. When developing with MySQL, developers need to pay attention to the case settings in MySQL.

In MySQL, there are three case setting methods:

1. Server default case setting
2. Database table default case setting
3. Case settings in SQL statements

Let’s introduce these three case setting methods respectively.

1. Server default case settings

On the MySQL server side, you can control MySQL's sensitivity to the case of database table names, database names, and field names by setting the parameter lower_case_table_names sex. This parameter can be set to one of the following three values:

• 0: Indicates that MySQL's case sensitivity for database table names, database names, and field names is consistent with the case sensitivity of the operating system.
• 1: Indicates that MySQL converts all case sensitivity of database table names, database names, and field names into lowercase, and is not case-sensitive.
• 2: Indicates that MySQL converts all case sensitivity of database table names, database names, and field names into uppercase, and is not case-sensitive.

Setting the lower_case_table_names parameter needs to be configured in the MySQL configuration file my.cnf. It should be noted that when using this parameter in the configuration file, the value of the parameter must be in uppercase.

2. Default case settings for database tables

For the case sensitivity of database table names, database names and field names in MySQL, by default if it is never displayed If you specify the case, MySQL will use the case sensitivity of the operating system by default, that is, no case conversion will be performed.

To explicitly set the case sensitivity of a table name, developers can use the keyword BINARY before the table name when creating the table to force the case of the table name to be consistent. For example:

create table BINARY table_name (

column1 datatype,
column2 datatype,
.....

);

This statement means to create the table table_name and keep the case of the table name consistent without case conversion. .

For MySQL database names and field names, you can also use the keyword BINARY to specify case sensitivity. For example:

create database BINARY db_name;

3. Case settings in SQL statements

In SQL statements, you can also set the case for the database table name, Database names and field names are cased. There are two commonly used setting methods:

3.1 Use double quotes in SQL statements

In SQL statements, if a string enclosed in double quotes is used to represent a table name, database name, or field name, MySQL will process it. Case sensitivity is handled consistently and no case conversion is performed. For example:

select * from "table_name";

This statement means querying all data in table table_name without case conversion.

3.2 Using backticks in SQL statements

In SQL statements, if a string enclosed in backticks represents a table name, database name, or field name, MySQL will treat it as Be precise and case-sensitive. For example:

select * from table_Name;

This statement means querying all data in table table_Name and is case-sensitive.

Summary

When developing MySQL, the issue of capitalization is a point that developers must pay attention to. Developers need to enforce consistent case sensitivity by setting MySQL server parameters, using keywords in SQL statements, or using BINARY. Only by mastering the correct setting method can you operate smoothly in MySQL development.

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