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character set

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Java Captain
Java Captain
May 12, 2025 · Databases

Comprehensive Guide to Installing, Configuring, and Managing MySQL on CentOS Linux

This tutorial walks through preparing the environment, installing and uninstalling MySQL on CentOS 7, configuring firewalls, setting up remote access, handling character sets, adjusting security policies, managing SQL modes, and best practices for case sensitivity and version‑specific password policies.

ConfigurationInstallationLinux
0 likes · 30 min read
Comprehensive Guide to Installing, Configuring, and Managing MySQL on CentOS Linux
Aikesheng Open Source Community
Aikesheng Open Source Community
Jun 24, 2024 · Databases

Resolving Illegal Mix of Collations Error After Upgrading MySQL 5.7 to 8.0

This article explains why upgrading MySQL from 5.7 to 8.0 can cause an "Illegal mix of collations" error in FIND_IN_SET queries, analyzes the root cause, and presents three practical solutions—adjusting server parameters, altering table collations, or rewriting the SQL—to restore correct operation.

CollationMySQLSQL
0 likes · 10 min read
Resolving Illegal Mix of Collations Error After Upgrading MySQL 5.7 to 8.0
Efficient Ops
Efficient Ops
May 26, 2024 · Databases

Why MySQL’s “utf8” Isn’t Real UTF‑8 and How utf8mb4 Solves It

This article explains why MySQL’s built‑in utf8 charset only supports three‑byte characters, why emojis cause errors, and how switching to the proper utf8mb4 charset resolves insertion issues while preserving full Unicode support.

MySQLcharacter setdatabase
0 likes · 9 min read
Why MySQL’s “utf8” Isn’t Real UTF‑8 and How utf8mb4 Solves It
Aikesheng Open Source Community
Aikesheng Open Source Community
May 7, 2024 · Databases

Why Expanding a MySQL VARCHAR Column from 63 to 64 Characters Takes Much Longer

The article investigates why altering a MySQL VARCHAR column from a length that fits within 255 bytes to one that exceeds this limit (e.g., VARCHAR(63) to VARCHAR(64) in utf8mb4) triggers a costly copy operation, analyzes the storage mechanics, reproduces the issue, and provides practical recommendations to avoid performance penalties.

Database AdministrationMySQLVARCHAR
0 likes · 13 min read
Why Expanding a MySQL VARCHAR Column from 63 to 64 Characters Takes Much Longer
Aikesheng Open Source Community
Aikesheng Open Source Community
Dec 11, 2023 · Databases

Understanding utf8mb4 and Its Advantages in MySQL 8.0

This article explains the differences between utf8, utf8mb3 and utf8mb4 character sets in MySQL, demonstrates how utf8mb4 enables full Unicode support including emojis, and provides step‑by‑step SQL examples for creating tables, inserting data, and querying results with the proper character set.

MySQLUnicodecharacter set
0 likes · 12 min read
Understanding utf8mb4 and Its Advantages in MySQL 8.0
Tencent Database Technology
Tencent Database Technology
May 31, 2023 · Databases

MySQL Character Set Implementation: From System Tables to Source Code

This article explores MySQL character set implementation by analyzing system tables (CHARACTER_SETS and COLLATIONS) in information_schema and tracing internal source code structures like CHARSET_INFO, initialization logic, and client connection handling.

Client-Server ProtocolCollationDatabase Internals
0 likes · 6 min read
MySQL Character Set Implementation: From System Tables to Source Code
Aikesheng Open Source Community
Aikesheng Open Source Community
Feb 7, 2023 · Databases

Resolving Illegal Mix of Collations Errors in MySQL 8.0 Views

This article analyzes why MySQL 8.0 reports an illegal mix of collations when querying a view that joins tables with different character sets, demonstrates reproducing the issue, explains the role of the CONVERT function and default collation variables, and provides practical recommendations to avoid such errors.

CollationConvert FunctionDatabase Administration
0 likes · 9 min read
Resolving Illegal Mix of Collations Errors in MySQL 8.0 Views
php中文网 Courses
php中文网 Courses
Nov 9, 2022 · Databases

MySQL Slow Query Optimization: Live Demonstration on a Production To-Do List

This article walks through a real‑world MySQL slow‑query case, detailing analysis, index checks, character‑set alignment, forced index usage, and IN‑clause considerations that together reduced a 5‑second query to under one second.

IN clauseIndex OptimizationMySQL
0 likes · 4 min read
MySQL Slow Query Optimization: Live Demonstration on a Production To-Do List
Aikesheng Open Source Community
Aikesheng Open Source Community
Oct 17, 2022 · Databases

Understanding MySQL Collation and Character Set: Effects on Data Retrieval and Storage

This article explains MySQL collations and character sets, shows how to view and set them, and demonstrates through test cases that while data insertion is unaffected by collation, query results are influenced by the collation defined on columns or the connection.

CollationMySQLSQL
0 likes · 6 min read
Understanding MySQL Collation and Character Set: Effects on Data Retrieval and Storage
Aikesheng Open Source Community
Aikesheng Open Source Community
May 17, 2022 · Databases

Root Cause Analysis of Inconsistent MySQL Client Character Set on RedHat 7

The article investigates why two MySQL 5.7.32 installations on RedHat 7 show different client character sets—utf8 in the first batch and latin1 in the second—by reviewing MySQL charset settings, OS locale configuration, and providing corrective commands.

Database ConfigurationLinuxMySQL
0 likes · 7 min read
Root Cause Analysis of Inconsistent MySQL Client Character Set on RedHat 7
Aikesheng Open Source Community
Aikesheng Open Source Community
Mar 24, 2022 · Databases

Understanding MySQL Character Sets, Collations, and Common Encoding Issues

This article explains MySQL's various character sets and collations, describes important system variables such as character_set_client and character_set_connection, demonstrates how to query supported encodings, and provides practical examples for avoiding and fixing garbled text caused by mismatched encodings.

CollationMySQLSQL
0 likes · 10 min read
Understanding MySQL Character Sets, Collations, and Common Encoding Issues
政采云技术
政采云技术
Dec 7, 2021 · Databases

Analysis of MySQL Connector/J Character Set Handling and UTF8MB4 Support

This article examines how MySQL Connector/J determines the character set during connection initialization, explains the transition from UTF8MB3 to UTF8MB4, analyzes source code of versions 5.1.46 and 5.1.47, and provides practical methods to enable UTF8MB4 without upgrading the driver.

Connector/JJavaMySQL
0 likes · 10 min read
Analysis of MySQL Connector/J Character Set Handling and UTF8MB4 Support
Laravel Tech Community
Laravel Tech Community
Nov 22, 2021 · Databases

Understanding MySQL utf8 vs utf8mb4: Handling Emoji and Unicode Characters

This article explains why inserting emoji into MySQL fails with the default utf8 charset, demonstrates how switching to utf8mb4 resolves the issue, and provides a historical overview of MySQL's limited utf8 implementation and the proper use of true UTF‑8 encoding.

MySQLUnicodecharacter set
0 likes · 7 min read
Understanding MySQL utf8 vs utf8mb4: Handling Emoji and Unicode Characters
Top Architect
Top Architect
Sep 3, 2021 · Databases

Why MySQL’s “utf8” Is Not Real UTF‑8 and You Should Switch to utf8mb4

The article explains that MySQL’s legacy “utf8” charset only supports three‑byte characters, causing errors when storing true four‑byte UTF‑8 symbols, and shows how the newer “utf8mb4” charset provides full Unicode support, with historical context and migration guidance.

MariaDBMySQLcharacter set
0 likes · 7 min read
Why MySQL’s “utf8” Is Not Real UTF‑8 and You Should Switch to utf8mb4
Full-Stack Internet Architecture
Full-Stack Internet Architecture
May 23, 2021 · Databases

Understanding MySQL Unicode Support: utf8mb3 vs utf8mb4 and How to Migrate

This article explains MySQL's Unicode character set support, compares the deprecated utf8mb3 with the modern utf8mb4, and provides step‑by‑step SQL commands for safely converting existing databases to the newer charset.

MySQLUnicodecharacter set
0 likes · 7 min read
Understanding MySQL Unicode Support: utf8mb3 vs utf8mb4 and How to Migrate
Laravel Tech Community
Laravel Tech Community
Mar 22, 2021 · Databases

MySQL Index Not Used Due to Implicit Character Set Conversion and How to Fix It

This article explains why a MySQL join query may ignore an index because of implicit character‑set conversion, demonstrates how to diagnose the issue with EXPLAIN and schema queries, and provides a fix by converting the column to UTF8 in the SQL statement.

MySQLSQLcharacter set
0 likes · 4 min read
MySQL Index Not Used Due to Implicit Character Set Conversion and How to Fix It
Laravel Tech Community
Laravel Tech Community
Jan 7, 2021 · Databases

Understanding MySQL utf8 vs utf8mb4 and How to Store Emoji Correctly

This article explains why MySQL's legacy utf8 charset cannot store four‑byte characters such as emoji, demonstrates the resulting insertion error, and shows how switching the database, table, and column collations to utf8mb4 resolves the issue while also covering the historical reasons behind MySQL's limited utf8 implementation.

MySQLcharacter setdatabases
0 likes · 7 min read
Understanding MySQL utf8 vs utf8mb4 and How to Store Emoji Correctly
Tencent Database Technology
Tencent Database Technology
Dec 17, 2020 · Databases

Understanding MySQL Character Set Variables

This article explains the purpose and usage of MySQL character set system variables, illustrates how they affect client‑server communication and file handling, and provides practical examples and diagrams to help developers correctly configure character sets for optimal performance.

Database VariablesMySQLSQL
0 likes · 9 min read
Understanding MySQL Character Set Variables
Aikesheng Open Source Community
Aikesheng Open Source Community
Dec 8, 2020 · Databases

Understanding MySQL Online DDL for VARCHAR Column Size Changes and In‑Place vs Copy Operations

The article explains how MySQL's Online DDL handles VARCHAR column expansions, demonstrates performance differences across character sets using sysbench, and clarifies why certain size changes trigger in‑place alterations while others require full table copies, providing practical guidance for DBAs.

Database PerformanceInnoDBMySQL
0 likes · 9 min read
Understanding MySQL Online DDL for VARCHAR Column Size Changes and In‑Place vs Copy Operations
macrozheng
macrozheng
Aug 20, 2020 · Databases

Why MySQL’s utf8 Isn’t Real UTF‑8 and How utf8mb4 Fixes Emoji Errors

The article explains why MySQL’s built‑in utf8 charset only supports up to three‑byte characters, causing insert errors with four‑byte emojis, and shows how switching tables, system, and connection settings to utf8mb4 resolves the issue while detailing the historical reasons behind this limitation.

MySQLcharacter setdatabase encoding
0 likes · 9 min read
Why MySQL’s utf8 Isn’t Real UTF‑8 and How utf8mb4 Fixes Emoji Errors