這是歷史版本頁面 — 看 MySQL (32-bit) 最新版本
裝了 MySQL 之後不知道怎麼開始?它能做什麼、該不該用
你剛把 MySQL 裝好,打開黑色的命令提示字元視窗,輸入指令後卻不確定下一步要做什麼。或者你正在架一個網站、寫一支小程式,需要一個地方存放資料,聽別人說「用 MySQL 就好」,但你真的打開它之後,才發現跟想像中完全不一樣——沒有漂亮的視窗介面,只有一行一行的文字指令,你甚至不知道該從哪個指令開始。
一般人遇到這種狀況,直覺是去裝一個圖形介面工具,或是上網找教學影片。但問題往往不是「不會操作」,而是「不確定 MySQL 到底能幫你做到什麼程度」。它不像一般應用程式打開就能用,它是一套資料庫伺服器,需要你先理解「資料庫」的概念,才知道怎麼讓它為你工作。這類工具的核心切入點,是讓你把資料有結構地存起來、隨時查得回來,而不是像 Excel 那樣手動管理。
01MySQL 到底是做什麼用的?
它是一套關聯式資料庫管理系統,用來存放、管理、查詢資料。你可以把它想成一個「有結構的倉庫」——先把資料依照表格、欄位、關聯的方式規劃好,之後用 SQL 指令把資料寫進去或讀出來。網站會員資料、訂單紀錄、文章內容,這類需要頻繁讀寫的資料,都適合交給它處理。
02這套軟體一定要用指令操作嗎?
它本身主要透過命令提示字元操作,沒有內建圖形介面。但官方文件提到,可以搭配 phpMyAdmin、MySQL Workbench、Navicat 這些第三方工具,用滑鼠點一點就能建立表格、執行查詢、看效能狀態。如果你不習慣打指令,裝一個圖形工具會比較好上手。
03我原本用別的資料庫,可以把資料搬過來嗎?
官方說明指出,它提供工具和公用程式,可以從 Oracle、SQL Server、PostgreSQL 這些其他資料庫系統遷移過來。不過實際遷移的過程會牽涉到資料型別轉換、編碼設定等細節,建議先找官方文件確認支援的版本和步驟,再動手轉移。
04它支援寫入複雜的邏輯嗎?例如自動計算或觸發事件?
支援。官方文件明確列出它支援預存程序、觸發器和函數,意思是你可以把一段常用的 SQL 邏輯存起來重複呼叫,也可以在特定事件發生時自動執行某段程式。這對需要自動化處理資料的應用程式來說,是很常用的功能。
05資料放進去之後,要怎麼防止別人亂看?
它提供使用者認證、存取控制和加密機制。你可以建立不同的使用者帳號,分別設定他們能看哪些資料庫、能執行哪些操作,也可以啟用加密來保護傳輸中的資料。不過這些都需要你自己去設定,預設狀態下並不會自動幫你做好完整的權限控管。
06我完全沒寫過程式,適合用這套軟體嗎?
官方文件提到,要有效使用 MySQL,需要具備 SQL 語言的基本概念。如果你完全沒有接觸過資料庫,直接從指令開始會比較吃力。建議先學一點 SQL 語法,或從圖形介面工具開始操作,理解「表格、欄位、查詢」這些基本概念之後,再回來用指令會順很多。
07我只是做一個簡單的小專案,用這套會不會太重?
官方說明指出,它適合從小型應用到大規模企業系統。但如果你只是要存少量資料、不想管伺服器設定,官方文件也提到 SQLite 這類「免伺服器」的資料庫,特色是簡單、可攜、零設定。如果你的專案不需要多人同時連線、不需要複雜查詢,SQLite 可能更省事。
08這套軟體是免費的嗎?有沒有什麼限制?
它分為 Community Edition(免費、開放原始碼)和 Enterprise Edition(付費訂閱)。免費版功能已經很完整,但官方文件提到,進階功能像是即時分析、企業級技術支援,只有在付費的 Enterprise Edition 才有。如果你需要的是基本儲存和查詢,免費版通常夠用。
09我習慣用圖形介面,這套軟體有中文介面嗎?
它的介面語言是英文,而且主要操作介面是命令列。官方文件提到的第三方工具,像是 phpMyAdmin、MySQL Workbench,是否有中文介面需要另外確認。如果你很依賴中文介面,可能要考慮其他有提供在地化語言的資料庫工具,或先試用看看英文介面能不能接受。
10這套軟體在 Windows 上跑得順嗎?
官方說明指出,它支援 Windows、macOS 和 Linux,安裝過程通常是執行安裝程式、按幾個下一步。但官方文件也提醒,系統需求會依作業系統和版本而異,需要足夠的磁碟空間、記憶體和處理器效能。如果你的電腦規格比較舊,建議先確認官方列出的需求再安裝。
11我聽說 MySQL 很容易被駭,是真的嗎?
官方文件強調它提供多種驗證機制和加密選項來保護資料,但安全性很大程度取決於你怎麼設定。預設安裝完成後,如果你沒有修改預設帳號密碼、沒有設定防火牆規則,確實會有風險。建議安裝後第一件事就是設定強密碼、建立專用帳號,並關閉不需要的網路連線。
12這套軟體和 SQL Server Express 比起來,哪個比較適合我?
兩者都是免費的資料庫,但取向不同。SQL Server Express 是微軟的產品,和 Windows 環境、微軟開發工具整合較好;MySQL 則強調跨平台、支援多種程式語言。官方文件也提到,SQL Server 是 MySQL 的替代方案之一。如果你主要用微軟生態系,SQL Server Express 可能比較順;如果你需要跨平台或搭配開源技術,MySQL 會是常見選擇。
下載與官方連結
mysql-essential-5.0.41-win32.msi · 22.34 MB · 連結指向軟體原廠
版本紀錄
- 2026-08-04 MySQL 8.0.46.0 566 MB
- 2026-01-20 MySQL 8.0.45.0 556 MB
- 2025-10-22 MySQL 8.0.44.0 558 MB
再看 5 筆
- 2025-07-23 MySQL 8.0.43.0 354 MB
- 2025-07-22 MySQL 8.0.42.0 354 MB
- 2025-01-21 MySQL 8.0.41.0 352 MB
- 2024-10-16 MySQL 8.0.40.0 306 MB
- 2024-07-29 MySQL 8.0.39.0 285 MB
這一版改了什麼
What's new in this version:
Functionality added or changed:
- If you use SSL for a client connection, you can tell the client not to authenticate the server certificate by specifying neither --ssl-ca nor --ssl-capath. The server still verifies the client according to any applicable requirements established via GRANT statements for the client, and it still uses any --ssl-ca/--ssl-capath values that were passed to server at startup time. (Bug#25309)
- Prefix lengths for columns in SPATIAL indexes are no longer displayed in SHOW CREATE TABLE output. mysqldump uses that statement, so if a table with SPATIAL indexes containing prefixed columns is dumped and reloaded, the index is created with no prefixes. (The full column width of each column is indexed.) (Bug#26794)
- The output of mysql --xml and mysqldump --xml now includes a valid XML namespace. (Bug#25946)
- The mysql_create_system_tables script was removed because mysql_install_db no longer uses it in MySQL 5.0.
- The syntax for index hints has been extended to enable explicit specification that the hint applies only to join processing. See Section 13.2.7.2, Index Hint Syntax. (Bug#21174)
- Binary distributions for some platforms did not include shared libraries; now shared libraries are shipped for all platforms except AIX 5.2 64-bit. (Bug#13450, Bug#16520, Bug#26767)
- NDB Cluster: It is now possible to restore selected databases or tables using ndb_restore. (Bug#26899)
- NDB Cluster: Several options have been added for use with ndb_restore --print_data to facilitate the creation of data dump files. (Bug#26900)
- If a set function S with an outer reference S(outer_ref) cannot be aggregated in the outer query against which the outer reference has been resolved, MySQL interprets S(outer_ref) the same way that it would interpret S(const). However, standard SQL requires throwing an error in this situation. An error now is thrown for such queries if the ANSI SQL mode is enabled. (Bug#27348)
- To satisfy different user requirements, we provide several servers. mysqld is an optimized server that is a smaller, faster binary. Each package now also includes mysqld-debug, which is compiled with debugging support but is otherwise configured identically to the non-debug server.
- Added the --secure-file-priv option for mysql-test-run.pl, which limits the effect of the load_file command for mysqltest and for the LOAD DATA and SELECT ... INTO OUTFILE statements to work with files in a given directory. (Bug#18628)
- Added the hostname system variable, which the server sets at startup to the server hostname.
- The server now includes a timestamp in error messages that are logged as a result of unhandled signals (such as mysqld got signal 11 messages). (Bug#24878)
Bugs fixed:
- The patches for Bug#19370 and Bug#21789 were reverted.
- NDB Cluster: NDB tables having MEDIUMINT AUTO_INCREMENT columns were not restored correctly by ndb_restore, causing spurious duplicate key errors. This issue did not affect TINYINT, INT, or BIGINT columns with AUTO_INCREMENT. (Bug#27775)
- NDB Cluster: NDB tables with indexes whose names contained space characters were not restored correctly by ndb_restore (the index names were truncated). (Bug#27758)
- NDB Cluster: Some queries that updated multiple tables were not backed up correctly. (Bug#27748)
- NDB Cluster: Joins on multiple tables containing BLOB columns could cause data nodes run out of memory, and to crash with the error NdbObjectIdMap::expand unable to expand. (Bug#26176)
- NDB Cluster (APIs): Using NdbBlob::writeData() to write data in the middle of an existing blob value (that is, updating the value) could overwrite some data past the end of the data to be changed. (Bug#27018)
- NDB Cluster: Under certain rare circumstances, DROP TABLE or TRUNCATE of an NDB table could cause a node failure or forced cluster shutdown. (Bug#27581)
- NDB Cluster: Memory usage of a mysqld process grew even while idle. (Bug#27560)
- NDB Cluster: In some cases, AFTER UPDATE and AFTER DELETE triggers on NDB tables that referenced subject table did not see the results of operation which caused invocation of the trigger, but rather saw the row as it was prior to the update or delete operation.
This was most noticeable when an update operation used a subquery to obtain the rows to be updated. An example would be UPDATE tbl1 SET col2 = val1 WHERE tbl1.col1 IN (SELECT col3 FROM tbl2 WHERE c4 = val2) where there was an AFTER UPDATE trigger on table tbl1. In such cases, the trigger would fail to execute.
The problem occurred because the actual update or delete operations were deferred to be able to perform them later as one batch. The fix for this bug solves the problem by disabling this optimization for a given update or delete if the table has an AFTER trigger defined for this operation. (Bug#26242)
- NDB Cluster: Condition pushdown did not work with prepared statements. (Bug#26225)
- NDB Cluster: When trying to create tables on an SQL node not connected to the cluster, a misleading error message Table 'tbl_name' already exists was generated. The error now generated is Could not connect to storage engine. (Bug#18676)
- NDB Cluster: Error messages displayed when running in single user mode were inconsistent. (Bug#27021)
- NDB Cluster: On Solaris, the value of an NDB table column declared as BIT(33) was always displayed as 0. (Bug#26986)
- NDB Cluster: The output from ndb_restore --print_data was incorrect for a backup made of a database containing tables with TINYINT or SMALLINT columns. (Bug#26740)
- NDB Cluster: After entering single user mode it was not possible to alter non-NDB tables on any SQL nodes other than the one having sole access to the cluster. (Bug#25275)
- NDB Cluster: The failure of a data node while restarting could cause other data nodes to hang or crash. (Bug#27003)
- NDB Cluster: The management client command node_id STATUS displayed the message Node node_id: not connected when node_id was not the node ID of a data node. (Bug#21715)
Note
The ALL STATUS command in the cluster management client still displays status information for data nodes only. This is by design. See Section 15.7.2, Commands in the MySQL Cluster Management Client, for more information.
- NDB Cluster: It was not possible to set LockPagesInMainMemory equal to 0. (Bug#27291)
- NDB Cluster: A race condition could sometimes occur if the node acting as master failed while node IDs were still being allocated during startup. (Bug#27286)
- NDB Cluster: When a data node was taking over as the master node, a race condition could sometimes occur as the node was assuming responsibility for handling of global checkpoints. (Bug#27283)
- NDB Cluster: mysqld processes would sometimes crash under high load. (Bug#26825)
- NDB Cluster: Some values of MaxNoOfTables caused the error Job buffer congestion to occur. (Bug#19378)
- Some equi-joins containing a WHERE clause that included a NOT IN subquery caused a server crash. (Bug#27870)
- Windows binaries contained no debug symbol file. Now .map and .pdb files are included in 32-bit builds for mysqld-nt.exe, mysqld-debug.exe, and mysqlmanager.exe. (Bug#26893)
- The test for the MYSQL_OPT_SSL_VERIFY_SERVER_CERT option for mysql_options() was performed incorrectly. Also changed as a result of this bugfix: The arg option for the mysql_options() C API function was changed from char * to void *. (Bug#24121)
- The range optimizer could consume a combinatorial amount of memory for certain classes of WHERE clauses. (Bug#26624)
- Conversion of DATETIME values in numeric contexts sometimes did not produce a double (YYYYMMDDHHMMSS.uuuuuu) value. (Bug#16546)
- Passing nested row expressions with different structures to an IN predicate caused a server crash. (Bug#27484)
- SELECT DISTINCT could return incorrect results if the select list contained duplicated columns. (Bug#27659)
- A subquery could get incorrect values for references to outer query columns when it contained aggregate functions that were aggregated in outer context. (Bug#27321)
- In some cases, the optimizer preferred a range or full index scan access method over lookup access methods when the latter were much cheaper. (Bug#19372)
- Duplicates were not properly identified among (potentially) long strings used as arguments for GROUP_CONCAT(DISTINCT). (Bug#26815)
- For InnoDB, fixed consistent-read behavior of the first read statement, if the read was served from the query cache, for the READ COMMITTED isolation level. (Bug#21409)
- The decimal.h header file was incorrectly omitted from binary distributions. (Bug#27456)
- Duplicate members in SET definitions were not detected. Now they result in a warning; if strict SQL mode is enabled, an error occurs instead. (Bug#27069)
- For INSERT INTO ... SELECT where index searches used column prefixes, insert errors could occur when key value type conversion was done. (Bug#26207)
- For SHOW ENGINE INNODB STATUS, the LATEST DEADLOCK INFORMATION was not always cleared properly. (Bug#25494)
- mysqldump could crash or exhibit incorrect behavior when some options were given very long values, such as --fields-terminated-by="some very long string". The code has been cleaned up to remove a number of fixed-sized buffers and to be more careful about error conditions in memory allocation. (Bug#26346)
- Setting a column to NOT NULL with an ON DELETE SET NULL clause foreign key crashes the server. (Bug#25927)
- The values displayed for the Innodb_row_lock_time, Innodb_row_lock_time_avg, and Innodb_row_lock_time_max status variables were incorrect. (Bug#23666)
- COUNT(decimal_expr) sometimes generated a spurious truncation warning. (Bug#21976)
- With NO_AUTO_VALUE_ON_ZERO SQL mode enabled, LOAD DATA operations could assign incorrect AUTO_INCREMENT values. (Bug#27586)
- Incorrect results could be returned for some queries that contained a select list expression with IN or BETWEEN together with an ORDER BY or GROUP BY on the same expression using NOT IN or NOT BETWEEN. (Bug#27532)
- Queries containing subqueries with COUNT(*) aggregated in an outer context returned incorrect results. This happened only if the subquery did not contain any references to outer columns. (Bug#27257)
- Use of an aggregate function from an outer context as an argument to GROUP_CONCAT() caused a server crash. (Bug#27229)
- REPAIR TABLE ... USE_FRM with an ARCHIVE table deleted all records from the table. (Bug#26138)
- On Windows, debug builds of mysqld could fail with heap assertions. (Bug#25765)
- On Windows, debug builds of mysqlbinlog could fail with a memory error. (Bug#23736)
- String truncation upon insertion into an integer or year column did not generate a warning (or an error in strict mode). (Bug#26359, Bug#27176)
- In out-of-memory conditions, the server might crash or otherwise not report an error to the Windows event log. (Bug#27490)
- The temporary file-creation code was cleaned up on Windows to improve server stability. (Bug#26233)
- Out-of-memory errors for slave I/O threads were not reported. Now they are written to the error log. (Bug#26844)
- mysqldump crashed for MERGE tables if the --complete-insert (-c) option was given. (Bug#25993)
- In certain situations, MATCH ... AGAINST returned false hits for NULL values produced by LEFT JOIN when no full-text index was available. (Bug#25729)
- OPTIMIZE TABLE might fail on Windows when it attempts to rename a temporary file to the original name if the original file had been opened, resulting in loss of the .MYD file. (Bug#25521)
- GRANT statements were not replicated if the server was started with the --replicate-ignore-table or --replicate-wild-ignore-table option. (Bug#25482)
- A problem in handling of aggregate functions in subqueries caused predicates containing aggregate functions to be ignored during query execution. (Bug#24484)
- Improved out-of-memory detection when sending logs from a master server to slaves, and log a message when allocation fails. (Bug#26837)
- MBROverlaps() returned incorrect values in some cases. (Bug#24563)
- SHOW CREATE VIEW qualified references to stored functions in the view definition with the function's database name, even when the database was the default database. This affected mysqldump (which uses SHOW CREATE VIEW to dump views) because the resulting dump file could not be used to reload the database into a different database. SHOW CREATE VIEW now suppresses the database name for references to functions in the default database. (Bug#23491)
- With innodb_file_per_table enabled, attempting to rename an InnoDB table to a non-existent database caused the server to exit. (Bug#27381)
- mysql_install_db could terminate with an error after failing to determine that a system table already existed. (Bug#27022)
- For InnoDB tables having a clustered index that began with a CHAR or VARCHAR column, deleting a record and then inserting another before the deleted record was purged could result in table corruption. (Bug#26835)
- Selecting the result of AVG() within a UNION could produce incorrect values. (Bug#24791)
- An INTO OUTFILE clause is allowed only for the final SELECT of a UNION, but this restriction was not being enforced correctly. (Bug#23345)
- Duplicate entries were not assessed correctly in a MEMORY table with a BTREE primary key on a utf8 ENUM column. (Bug#24985)
- For MyISAM tables, COUNT(*) could return an incorrect value if the WHERE clause compared an indexed TEXT column to the empty string (''). This happened if the column contained empty strings and also strings starting with control characters such as tab or newline. (Bug#26231)
- For DELETE FROM tbl_name ORDER BY col_name (with no WHERE or LIMIT clause), the server did not check whether col_name was a valid column in the table. (Bug#26186)
- ALTER VIEW requires the CREATE VIEW and DROP privileges for the view. However, if the view was created by another user, the server erroneously required the SUPER privilege. (Bug#26813)
- In a view, a column that was defined using a GEOMETRY function was treated as having the LONGBLOB data type rather than the GEOMETRY type. (Bug#27300)
- With the NO_AUTO_VALUE_ON_ZERO SQL mode enabled, LAST_INSERT_ID() could return 0 after INSERT ... ON DUPLICATE KEY UPDATE. Additionally, the next rows inserted (by the same INSERT, or the following INSERT with or without ON DUPLICATE KEY UPDATE), would insert 0 for the auto-generated value if the value for the AUTO_INCREMENT column was NULL or missing. (Bug#23233)
- For a stored procedure containing a SELECT statement that used a complicated join with an ON expression, the expression could be ignored during re-execution of the procedure, yielding an incorrect result. (Bug#20492)
- When RAND() was called multiple times inside a stored procedure, the server did not write the correct random seed values to the binary log, resulting in incorrect replication. (Bug#25543)
- SOUNDEX() returned an invalid string for international characters in multi-byte character sets. (Bug#22638)
- Row equalities in WHERE clauses could cause memory corruption. (Bug#27154)
- GROUP BY on a ucs2 column caused a server crash when there was at least one empty string in the column. (Bug#27079)
- Evaluation of an IN() predicate containing a decimal-valued argument caused a server crash. (Bug#27362)
- Storing NULL values in spatial fields caused excessive memory allocation and crashes on some systems. (Bug#27164)
- mysql_stmt_fetch() did an invalid memory deallocation when used with the embedded server. (Bug#25492)
- In a MEMORY table, using a BTREE index to scan for updatable rows could lead to an infinite loop. (Bug#26996)
- The range optimizer could cause the server to run out of memory. (Bug#26625)
- The parser accepted illegal code in SQL exception handlers, leading to a crash at runtime when executing the code. (Bug#26503)
- Difficult repair or optimization operations could cause an assertion failure, resulting in a server crash. (Bug#25289)
- Increasing the width of a DECIMAL column could cause column values to be changed. (Bug#24558)
- Replication between master and slave would infinitely retry binary log transmission where the max_allowed_packet on the master was larger than that on the slave if the size of the transfer was between these two values. (Bug#23775)
- Invalid optimization of pushdown conditions for queries where an outer join was guaranteed to read only one row from the outer table led to results with too few rows. (Bug#26963)
- For INSERT ... ON DUPLICATE KEY UPDATE statements on tables containing AUTO_INCREMENT columns, LAST_INSERT_ID() was reset to 0 if no rows were successfully inserted or changed. Not changed includes the case where a row was updated to its current values, but in that case, LAST_INSERT_ID() should not be reset to 0. Now LAST_INSERT_ID() is reset to 0 only if no rows were successfully inserted or touched, whether or not touched rows were changed. (Bug#27033)
This bug was introduced by the fix for Bug#19978.
- For an INSERT statement that should fail due to a column with no default value not being assigned a value, the statement succeeded with no error if the column was assigned a value in an ON DUPLICATE KEY UPDATE clause, even if that clause was not used. (Bug#26261)
- A result set column formed by concatention of string literals was incomplete when the column was produced by a subquery in the FROM clause. (Bug#26738)
- When using the result of SEC_TO_TIME() for time value greater than 24 hours in an ORDER BY clause, either directly or through a column alias, the rows were sorted incorrectly as strings. (Bug#26672)
- If the server was started with --skip-grant-tables, Selecting from INFORMATION_SCHEMA tables causes a server crash. (Bug#26285)
- Incompatible change: INSERT DELAYED statements are not supported for MERGE tables, but the MERGE storage engine was not rejecting such statements, resulting in table corruption. Applications previously using INSERT DELAYED into MERGE table will break when upgrading to versions with this fix. To avoid the problem, remove DELAYED from such statements. (Bug#26464)
- NDB Cluster: An invalid pointer was returned following a FSCLOSECONF signal when accessing the REDO logs during a node restart or system restart. (Bug#26515)
- NDB Cluster: An inadvertent use of unaligned data caused ndb_restore to fail on some 64-bit platforms, including Sparc and Itanium-2. (Bug#26739)
- NDB Cluster: An infinite loop in an internal logging function could cause trace logs to fill up with Unknown Signal type error messages and thus grow to unreasonable sizes. (Bug#26720)
- NDB Cluster: The failure of a data node when restarting it with --initial could lead to failures of subsequent data node restarts. (Bug#26481)
- NDB Cluster: Takeover for local checkpointing due to multiple failures of master nodes was sometimes incorrect handled. (Bug#26457)
- NDB Cluster: The LockPagesInMemory parameter was not read until after distributed communication had already started between cluster nodes. When the value of this parameter was 1, this could sometimes result in data node failure due to missed heartbeats. (Bug#26454)
- NDB Cluster: Under some circumstances, following the restart of a management, all cluster data nodes would connect to it normally, but some of them subsequently failed to log any events to the management node. (Bug#26293)
- NDB Cluster: An error was produced when SHOW TABLE STATUS was used on an NDB table that had no AUTO_INCREMENT column. (Bug#21033)
- SELECT ... INTO OUTFILE with a long FIELDS ENCLOSED BY value could crash the server. (Bug#27231)
- DOUBLE values such as 20070202191048.000000 were being treated as illegal arguments by WEEK(). (Bug#23616)
- AFTER UPDATE triggers were not activated by the update part of INSERT ... ON DUPLICATE KEY UPDATE statements. (Bug#27006, Bug#27210)
This bug was introduced by the fix for Bug#19978.
- For INSERT ... ON DUPLICATE KEY UPDATE statements where some AUTO_INCREMENT values were generated automatically for inserts and some rows were updated, one auto-generated value was lost per updated row, leading to faster exhaustion of the range of the AUTO_INCREMENT column. (Bug#24432)
Because the original problem can affect replication (different values on master and slave), it is recommended that the master and its slaves be upgraded to the current version.
- IN ((subquery)), IN (((subquery))), and so forth, are equivalent to IN (subquery), which is always interpreted as a table subquery (so that it is allowed to return more than one row). MySQL was treating the over-parenthesized subquery as a single-row subquery and rejecting it if it returned more than one row. This bug primarily affected automatically generated code (such as queries generated by Hibernate), because humans rarely write the over-parenthesized forms. (Bug#21904)
- For MERGE tables defined on underlying tables that contained a short VARCHAR column (shorter than four characters), using ALTER TABLE on at least one but not all of the underlying tables caused the table definitions to be considered different from that of the MERGE table, even if the ALTER TABLE did not change the definition. (Bug#26881)
- If a thread previously serviced a connection that was killed, excessive memory and CPU use by the thread occurred if it later serviced a connection that had to wait for a table lock. (Bug#25966)
- CURDATE() is less than NOW(), either when comparing CURDATE() directly (CURDATE() < NOW() is true) or when casting CURDATE() to DATE (CAST(CURDATE() AS DATE) < NOW() is true). However, storing CURDATE() in a DATE column and comparing col_name < NOW() incorrectly yielded false. This is fixed by comparing a DATE column as DATETIME for comparisons to a DATETIME constant. (Bug#21103)
- A view on a join is insertable for INSERT statements that store values into only one table of the join. However, inserts were being rejected if the inserted-into table was used in a self-join because MySQL incorrectly was considering the insert to modify multiple tables of the view. (Bug#25122)
- Expressions involving SUM(), when used in an ORDER BY clause, could lead to out-of-order results. (Bug#25376)
- LOAD DATA INFILE sent an okay to the client before writing the binary log and committing the changes to the table had finished, thus violating ACID requirements. (Bug#26050)
- Views that used a scalar correlated subquery returned incorrect results. (Bug#26560)
- IF(expr, unsigned_expr, unsigned_expr) was evaluated to a signed result, not unsigned. This has been corrected. The fix also affects constructs of the form IS [NOT] {TRUE|FALSE}, which were transformed internally into IF() expressions that evaluated to a signed result. (Bug#24532)
For existing views that were defined using IS [NOT] {TRUE|FALSE} constructs, there is a related implication. The definitions of such views were stored using the IF() expression, not the original construct. This is manifest in that SHOW CREATE VIEW shows the transformed IF() expression, not the original one. Existing views will evaluate correctly after the fix, but if you want SHOW CREATE VIEW to display the original construct, you must drop the view and re-create it using its original definition. New views will retain the construct in their definition.
- BENCHMARK() did not work correctly for expressions that produced a DECIMAL result. (Bug#26093)
- For some values of the position argument, the INSERT() function could insert a NUL byte into the result. (Bug#26281)
- Inserting utf8 data into a TEXT column that used a single-byte character set could result in spurious warnings about truncated data. (Bug#25815)
- EXPLAIN EXTENDED did not show WHERE conditions that were optimized away. (Bug#22331)
- INSERT DELAYED statements inserted incorrect values into BIT columns. (Bug#26238)
- For expr IN(value_list), the result could be incorrect if BIGINT UNSIGNED values were used for expr or in the value list. (Bug#19342)
- When a TIME_FORMAT() expression was used as a column in a GROUP BY clause, the expression result was truncated. (Bug#20293)
- For SUBSTRING() evaluation using a temporary table, when SUBSTRING() was used on a LONGTEXT column, the max_length metadata value of the result was incorrectly calculated and set to 0. Consequently, an empty string was returned instead of the correct result. (Bug#15757)
- Use of a GROUP BY clause that referred to a stored function result together with WITH ROLLUP caused incorrect results. (Bug#25373)
- Use of a subquery containing GROUP BY and WITH ROLLUP caused a server crash. (Bug#26830)
- Use of a subquery containing a UNION with an invalid ORDER BY clause caused a server crash. (Bug#26661)
- In certain cases it could happen that deleting a row corrupted an RTREE index. This affected indexes on spatial columns. (Bug#25673)
- SSL connections failed on Windows. (Bug#26678)
- Added support for --debugger=dbx for mysql-test-run.pl and fixed support for --debugger=devenv, --debugger=DevEnv, and --debugger=/path/to/devenv. (Bug#26792)
- X() IS NULL and Y() IS NULL comparisons failed when X() and Y() returned NULL. (Bug#26038)
- UNHEX() IS NULL comparisons failed when UNHEX() returned NULL. (Bug#26537)
- The REPEAT() function did not allow a column name as the count parameter. (Bug#25197)
- On 64-bit Windows, large timestamp values could be handled incorrectly. (Bug#26536)
- In some error messages, inconsistent format specifiers were used for the translations in different languages. comp_err (the error message compiler) now checks for mismatches. (Bug#26571)
- On Windows, the server exhibited a file-handle leak after reaching the limit on the number of open file descriptors. (Bug#25222)
- A reference to a non-existent column in the ORDER BY clause of an UPDATE ... ORDER BY statement could cause a server crash. (Bug#25126)
- A multiple-row delayed insert with an auto increment column could cause duplicate entries to be created on the slave in a replication environment. (Bug#25507, Bug#26116)
- Duplicating the usage of a user variable in a stored procedure or trigger would not be replicated correctly to the slave. (Bug#25167)
- User defined variables used within stored procedures and triggers are not replicated correctly when operating in statement-based replication mode. (Bug#20141, Bug#14914)
- Loading data using LOAD DATA INFILE may not replicate correctly (due to character set incompatibilities) if the character_set_database variable is set before the data is loaded. (Bug#15126)
- DROP TRIGGER statements would not be filtered on the slave when using the replication-wild-do-table option. (Bug#24478)
- MySQL would not compile when configured using --without-query-cache. (Bug#25075)
- When using certain server SQL modes, the mysql.proc table was not created by mysql_install_db. In addition, the creation of this and other MySQL system tables was not checked for by mysql-test-run.pl. (Bug#23669, Bug#20166)
- VIEW restrictions were applied to SELECT statements after a CREATE VIEW statement failed, as though the CREATE had succeeded. (Bug#25897)
- An INSERT trigger invoking a stored routine that inserted into a table other than the one on which the trigger was defined would fail with a Table '...' doesn't exist referring to the second table when attempting to delete records from the first table. (Bug#21825)
- A stored procedure that made use of cursors failed when the procedure was invoked from a stored function. (Bug#25345)
- When nesting stored procedures within a trigger on a table, a false dependency error was thrown when one of the nested procedures contained a DROP TABLE statement. (Bug#22580)
- When attempting to call a stored procedure creating a table from a trigger on a table tbl in a database db, the trigger failed with ERROR 1146 (42S02): Table 'db.tbl' doesn't exist. However, the actual reason that such a trigger fails is due to the fact that CREATE TABLE causes an implicit COMMIT, and so a trigger cannot invoke a stored routine containing this statement. A trigger which does so now fails with ERROR 1422 (HY000): Explicit or implicit commit is not allowed in stored function or trigger, which makes clear the reason for the trigger's failure. (Bug#18914)
- Local variables in stored routines or triggers, when declared as the BIT type, were interpreted as strings. (Bug#12976)
- When a stored routine attempted to execute a statement accessing a nonexistent table, the error was not caught by the routine's exception handler. (Bug#8407, Bug#20713)
- NOW() returned the wrong value in statements executed at server startup with the --init-file option. (Bug#23240)
- Instance Manager did not remove the angel PID file on a clean shutdown. (Bug#22511)
- The server could crash if two or more threads initiated query cache resize operation at moments very close in time. (Bug#23527)
- The conditions checked by the optimizer to allow use of indexes in IN predicate calculations were unnecessarily tight and were relaxed. (Bug#20420)
- Several deficiencies in resolution of column names for INSERT ... SELECT statements were corrected. (Bug#25831)
- Indexes on TEXT columns were ignored when ref accesses were evaluated. (Bug#25971)
- The update columns for INSERT ... SELECT ... ON DUPLICATE KEY UPDATE could be assigned incorrect values if a temporary table was used to evaluate the SELECT. (Bug#16630)
- CONNECTION is no longer treated as a reserved word. (Bug#12204)
- A user-defined variable could be assigned an incorrect value if a temporary table was employed in obtaining the result of the query used to determine its value. (Bug#24010)
- Queries that used a temporary table for the outer query when evaluating a correlated subquery could return incorrect results. (Bug#23800)
- For index reads, the BLACKHOLE engine did not return end-of-file (which it must because BLACKHOLE tables contain no rows), causing some queries to crash. (Bug#19717)