The difference between SQL and PLSQL

Modifying the default root password, deleting anonymous users, banning remote root login, removing test databases, and restricting access ports are key steps in MySQL security hardening. First, use the ALTERUSER command to set a strong password and avoid using the root account to connect to the application; secondly, delete anonymous users'@'localhost' and ''@'your_hostname' through DROPUSER; then check and delete the 'root'@'%' account that allows remote login, or create a restricted dedicated account instead; then delete unnecessary test databases and other irrelevant data; finally restrict port 3306 access through firewall tools, or set bind-addres in the configuration file

MySQL indexes are not as fast as possible, and they need to be used reasonably according to the query scenario. 1. The WHERE condition medium value query (=) has the best effect. The range query must comply with the principle of leftmost prefix. Fuzzy match LIKE'abc%' can be indexed, LIKE'�c' is not available, and functions or expressions are avoided in the condition. 2. ORDERBY needs to use indexes to avoid file sorting. It requires that the sorting columns have indexes and the WHERE and ORDERBY columns are in the same order to form a joint index, but range query may cause the sorting to be invalid. 3. GROUPBY recommends using an existing index structure, which prioritizes indexes covering equivalent conditions. Discontinuous columns or inappropriate order will add additional overhead. In addition, the EXPLAIN tool should be paid attention to the implementation plan

Common solutions to the MySQL master-slave synchronization problem are as follows: 1. Check whether the master-slave connection is normal, check the error information of the Last_IO_Error and Last_SQL_Error fields to ensure that the main library port is open and the slave library account has REPLICATIONSLAVE permission; 2. Check whether there are SQL execution errors, if the table does not exist or the field type does not match, skip the error and continue synchronization if necessary; 3. Fix data inconsistency, resynchronize full amount through mysqldump or PerconaXtraBackup, or use pt-table-checksum to detect and repair differences; 4. Optimize configuration and adjust sync_binlog and slave_parall

InnoDB is suitable for scenarios where transactions, foreign keys, and row-level locks are required. 2. MyISAM is suitable for scenarios where more reads, less writes, and 3. Modern MySQL recommends using InnoDB by default. InnoDB supports transaction processing, crash recovery, foreign key constraints and row-level locking, and is suitable for scenarios with high data consistency requirements such as financial transactions and order processing, with good concurrency performance and high reliability; MyISAM is simple in design and fast query speed, suitable for scenarios where reading operations are mainly based on log statistics and report analysis, but write operations will lock the entire table, affecting concurrency performance; Since MySQL5.5, InnoDB has become the default engine, and continues to obtain new functions and is more applicable. Unless there are special needs, it is recommended to choose InnoDB to avoid late migration costs.

MySQL master-slave replication issues are usually caused by improper configuration of replication user rights. 1. Make sure that the replica user has REPLICATIONSLAVE permissions, which can be checked through SHOWGRANTS and added with the GRANT command; 2. Avoid over-authorization and only grant necessary permissions such as REPLICATIONSLAVE and REPLICATIONCLIENT; 3. Check whether the permissions are effective, confirm that there are no spelling errors, FLUSHPRIVILEGES has been executed, the database modification is correct, and MySQL restart is restarted; 4. If the error "Accessdeniedforuser" is reported, the user name and password host should be confirmed, the user existence, firewall and port connectivity should be confirmed.

TooptimizeMySQLforsocialmediaplatforms,startwithindexingstrategies,schemadesign,queryoptimization,andconnectionhandling.1)Usecompositeandcoveringindexeswiselytospeedupquerieswithoutslowingdownwrites.2)Normalizecoredataforconsistencyanddenormalizesele

TooptimizeMySQLforgamingleaderboardsandplayerstats,useproperdatatypesandindexing,optimizequerieswithwindowfunctions,implementcaching,andconsiderpartitioningorshardingatscale.First,useINTorBIGINTforscoresandDECIMALforfractionalvalues,andapplycompoundi

To avoid exposing the management interface to the public network, it should be accessed through SSH tunnels or intranets; 2. Use a dedicated account and strictly control permissions, disable root remote login; 3. Enable SSL encryption transmission, set strong password policies and cookie authentication; 4. Regularly update the MySQL version and monitor log audit operations. If the MySQL management interface is not protected properly, it should restrict access methods, strengthen authentication, encrypt communications and continuously monitor security status.