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  • how to set up mysql master slave replication
    how to set up mysql master slave replication
    The key to setting up MySQL master-slave replication is configuration synchronization, permission allocation and network interoperability. 1. Preparation includes ensuring that the two MySQL instances are running normally, with the consistent version, clear IP, and opening the 3306 port and firewall settings; 2. Configuring the main library requires enabling binary logs, setting a unique server-id, creating a copy account and authorizing it, and recording the file and Position of the main library status; 3. Configuring the slave library requires setting different server-ids, configuring relay logs, connecting to the main library and starting the replication process; 4. Frequently asked questions should check the network, user permissions, server-id uniqueness, binlog and relaylog settings and password correctness, combined with SHOWSLAVESTA
    Mysql Tutorial . Database 1013 2025-07-15 02:20:10
  • how to reset mysql root password
    how to reset mysql root password
    To reset MySQL's root password, you need to follow the following steps: 1. Stop MySQL service and use commands suitable for your system, such as sudosystemctlstopmysql or brewservicesstopmysql; 2. Start MySQL in --skip-grant-tables mode, such as sudomysqld_safe-skip-grant-tables&; 3. After logging in to MySQL, modify the password according to the version, use UPDATE statements for MySQL5.7 and earlier versions, use the ALTERUSER command for MySQL8.0 and above; 4. Exit MySQL and correct
    Mysql Tutorial . Database 633 2025-07-15 02:15:10
  • Using window functions for analytical queries in MySQL 8
    Using window functions for analytical queries in MySQL 8
    WindowfunctionsinMySQL8 enabledetaileddataanalysiswhilepreservingindividualrowcontext.Theysupportrunningtotals,rankings,andmovingaverageswithoutcollapsingdata.KeyfunctionsincludeRANK(),ROW_NUMBER(),DENSE_RANK(),andaggregatewindowfunctionslikeSUM()and
    Mysql Tutorial . Database 840 2025-07-15 02:12:21
  • mysql last_day function
    mysql last_day function
    MySQL's LAST_DAY() function is used to return the last day of the month where the specified date is. For example, inputting '2024-03-15' will return '2024-03-31'; common uses include: 1. Use DAY() function to calculate the total number of days in a certain month. For example, SELECTDAY(LAST_DAY('2024-02-01')) to determine that there are 29 days in February 2024; 2. Filter the records of the date field as the last day of the month in the query, such as WHEREorder_date=LAST_DAY(order_date); 3. Note that the input must be in a legal date format, otherwise NULL will be returned, and data validity must be ensured or ISNOTNU is used.
    Mysql Tutorial . Database 597 2025-07-15 02:01:01
  • how to calculate a running total in mysql
    how to calculate a running total in mysql
    TocalculatearunningtotalinMySQL,usewindowfunctionsinMySQL8.0 orsimulatewithvariablesinolderversions.InMySQL8.0 ,applytheSUM()functionwithanOVER()clausetocomputethecumulativesum,optionallysimplifyingthewindowframespecification.Forolderversions,initial
    Mysql Tutorial . Database 229 2025-07-15 01:57:10
  • Strategies for Improving Write Performance in MySQL
    Strategies for Improving Write Performance in MySQL
    Optimizing MySQL write performance requires starting from multiple aspects. 1. Use batch insertion to merge multiple pieces of data into one INSERT statement to execute. It is recommended to control it to 500 to 1,000 pieces each time. 2. Adjust the transaction commit frequency, wrap multiple operations in one transaction and submit them uniformly, and set innodb_flush_log_at_trx_commit=2 to reduce disk I/O. 3. Adopt appropriate indexing strategies to avoid unnecessary indexes, delete unnecessary indexes before importing data and rebuild after importing. It is recommended to use self-incremental integers for the primary key. 4. Rationally configure InnoDB parameters, such as increasing innodb_buffer_pool_size, innodb_log_file_s
    Mysql Tutorial . Database 353 2025-07-15 01:55:01
  • mysql getting the first record in each group
    mysql getting the first record in each group
    TogetthefirstrecordineachgroupinMySQL,usewindowfunctionsinMySQL8.0 oraselfjoininolderversions.1.InMySQL8.0 ,useROW_NUMBER()OVER(PARTITIONBYgroup_columnORDERBYsort_column)inasubqueryandfilterforrn=1.2.Inpre-8.0versions,performaselfjoinbyselectingthemi
    Mysql Tutorial . Database 371 2025-07-15 01:54:41
  • Essential Security Measures for MySQL Database Servers
    Essential Security Measures for MySQL Database Servers
    To ensure the security of MySQL database server, the following key measures need to be taken: 1. Close unnecessary services and ports, ensure that MySQL only listens to intranet or local loopback addresses, and restricts access sources through firewalls or security groups; 2. Set up a strong password and reasonably allocate user permissions, disable anonymous users and remote root logins to avoid excessive authorization; 3. Establish a regular backup mechanism and store the backup files in an independent location, and enable various logs for monitoring; 4. Timely update the MySQL and operating system version, pay attention to the official patches and test them before launching. These basic but important steps can effectively improve database security.
    Mysql Tutorial . Database 137 2025-07-15 01:50:10
  • how to kill a process in mysql
    how to kill a process in mysql
    MySQL provides a method to terminate running a connection or query. First, check the active thread through SHOWPROCESSLIST to obtain the thread ID; then use KILL[thread_id] to terminate the specified thread, but pay attention to permissions, termination delay and data consistency issues; it is recommended to regularly check abnormal connections with monitoring tools, and set a timeout mechanism in automated scripts to avoid blockage.
    Mysql Tutorial . Database 537 2025-07-15 01:30:50
  • mysql right join example
    mysql right join example
    RIGHTJOIN is used in MySQL to return all records in the right table. Even if there is no matching row on the left table, the left table field is displayed as NULL. Its syntax is the SELECT column name FROM left table RIGHTJOIN right table ON condition, which is suitable for finding data of "right table has but left table has no", such as finding customers who have not placed an order. When using it, you need to pay attention to the field alias, filtering conditions position and performance differences. You can also use LEFTJOIN to achieve the same effect by changing table order.
    Mysql Tutorial . Database 405 2025-07-15 01:19:20
  • Adding, Modifying, or Deleting Columns with ALTER TABLE in MySQL
    Adding, Modifying, or Deleting Columns with ALTER TABLE in MySQL
    MySQL's ALTERTABLE statement is used to adjust the table structure and supports adding, modifying and deleting columns. 1. Use ADDCOLUMN to add a new column, and you can specify the location; 2. Use MODIFYCOLUMN to modify the column, and you need to pay attention to data conversion and dependency objects; 3. Use DROPCOLUMN to delete the column, and the operation is irreversible and the dependency will be cleared; 4. Multiple operations can be performed at once, and it is recommended to check the structure through DESCRIBE or SHOWCREATETABLE. Verify it in the test environment before operating in the production environment.
    Mysql Tutorial . Database 979 2025-07-15 01:14:41
  • mysql rename column
    mysql rename column
    MySQL8.0 uses RENAMECOLUMN to modify the column name, and the syntax is ALTERTABLE table name RENAMECOLUMN old column name TO new column name; 1. When the version is lower than 8.0, you need to use ALTERTABLE table name CHANGE old column name new column name column name column type to achieve renaming; 2. When using RENAMECOLUMN, please note that AS or CHANGE keywords cannot be used; 3. The CHANGE method must specify the data type of the column; 4. The operation must have ALTER permission and the table will be locked, and the operation of large tables should avoid peak periods; 5. The index, foreign key, and triggers of the original column are still valid after renaming, but the field comments need to be updated manually.
    Mysql Tutorial . Database 137 2025-07-15 01:13:41
  • mysql json data type query examples
    mysql json data type query examples
    MySQL supports JSON data types since 5.7, which facilitates the storage and operation of unfixed or nested data. 1. Query the JSON field value and can be used -> or JSON_EXTRACT(), such as profile->'$.address.city' to extract the city; 2. Conditional query can be used ->>Unquoted marks or JSON_CONTAINS to determine the inclusion relationship, such as filtering users living in Beijing; 3. Update JSON to modify some content using functions such as JSON_SET, JSON_REPLACE, etc., such as adding mobile phone numbers or modifying city information. Mastering these common operations can efficiently process JSON data.
    Mysql Tutorial . Database 919 2025-07-15 00:57:20
  • mysql change column data type
    mysql change column data type
    Modify MySQL field type with ALTERTABLE...MODIFY or CHANGE statement 1.MODIFY is used to change the type only, such as ALTERTABLEusersMODIFYageVARCHAR(10); 2. CHANGE can be changed at the same time, such as ALTERTABLEusersCHANGEageuser_ageVARCHAR(10); pay attention to data conversion risks, such as INT to VARCHAR lossless, otherwise an error may occur; the original constraints such as NOTNULL, DEFAULT, etc. must be added during operation; modifying the type may lock table reconstruction, affecting performance, and it is recommended to execute at low peaks; common scenarios include VA
    Mysql Tutorial . Database 420 2025-07-14 02:39:31

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