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  • how to get current quarter from date in mysql
    how to get current quarter from date in mysql
    The function to get the quarter where the date is in MySQL is QUARTER(). Use QUARTER(date) to directly return quarterly values ??between 1 and 4; you can also use CURDATE() to obtain the current quarter; if you need to be compatible with other databases or manually calculate, you can extract the month by MONTH(date) and calculate the quarter through formula (month 2) DIV3.
    Mysql Tutorial . Database 114 2025-07-09 00:50:51
  • when should i create an index in mysql
    when should i create an index in mysql
    The timing of creating an index includes: 1. Query frequently uses a certain field as a filtering condition, especially when it can significantly reduce the result set, it is suitable to add single columns or composite indexes, but avoid fields with low distinction; 2. Fields that are often used for JOIN operations should be indexed, and the index order should be consistent with the JOIN order; 3. Indexes can be used to avoid additional sorting, pay attention to index direction and order matching; 4. Overwriting indexes are suitable for scenes where all fields are included in the index, reducing back-to-table query, and improving reading efficiency.
    Mysql Tutorial . Database 817 2025-07-09 00:48:51
  • Updating Existing Records in a MySQL Table with Specific Conditions
    Updating Existing Records in a MySQL Table with Specific Conditions
    The key to safely and efficiently updating records in MySQL is to use WHERE conditions and reasonable structures accurately. 1. Use the WHERE clause to limit the update scope to ensure accurate conditions. Use SELECT to check the matching data before update; 2. During batch updates, you can use the CASEWHEN structure to achieve differentiated updates of multiple records to improve efficiency; 3. Pay attention to performance issues, such as adding indexes, avoiding full table scanning, using LIKE and functions with caution, and it is recommended that the test environment be verified first.
    Mysql Tutorial . Database 193 2025-07-09 00:46:21
  • mysql find and replace in string
    mysql find and replace in string
    In MySQL, the REPLACE() function can replace the string in the field. The syntax is UPDATE table name SET field name =REPLACE (field name, 'old content', 'new content'); 1. This operation is replaced globally and case-sensitive; 2. It is recommended to backup or add WHERE conditional test before execution; 3. The replacement effect can be previewed in SELECT; 4. Pay attention to avoiding error substitution, performance impact and data backup problems.
    Mysql Tutorial . Database 815 2025-07-09 00:44:20
  • how to get last inserted id in mysql
    how to get last inserted id in mysql
    The core method for getting the last inserted ID in MySQL is to use the LAST_INSERT_ID() function, which returns the autoincrement ID generated by the last insertion in the current connection. 1. Get the ID directly after insertion: call LAST_INSERT_ID() immediately after executing the INSERT statement, which is suitable for tables with auto-incremental primary keys; 2. Used in programming languages: For example, PDO extension of PHP calls the function through lastInsertId() and Python's mysql-connector through lastrowid package; 3. Performance when inserting multiple lines: Return the ID of the first insert record, not the last; 4. Notes include: Connection isolation ensures that it is not affected.
    Mysql Tutorial . Database 606 2025-07-09 00:23:40
  • mysql data types explained
    mysql data types explained
    ChoosingtherightMySQLdatatypeimprovesstorage,performance,andquerybehavior.1.UseINTforgeneralwholenumbers,TINYINTforsmallranges,DECIMALforexactprecision(e.g.,financialdata),FLOAT/DOUBLEforapproximatescientificvalues,andavoidoverusingBIGINT.2.ChooseCHA
    Mysql Tutorial . Database 649 2025-07-09 00:04:50
  • Working with JSON data type in MySQL
    Working with JSON data type in MySQL
    MySQL supports JSON data types introduced since version 5.7 to handle structured and semi-structured data. 1. When inserting JSON data, you must use a legal format. You can use JSON_OBJECT or JSON_ARRAY functions to construct, or pass in the correct JSON string; 2. Updates should use JSON_SET, JSON_REPLACE, JSON_REMOVE to modify some fields instead of the entire replacement; 3. Query can extract fields through JSON_CONTAINS, -> operators, and note that the string value needs to be double quoted; 4. It is recommended to create a generated column and index to improve performance when using JSON type.
    Mysql Tutorial . Database 742 2025-07-08 02:57:21
  • Understanding the MySQL optimizer's behavior
    Understanding the MySQL optimizer's behavior
    The MySQL query optimizer selects the optimal execution plan based on statistical information. The core mechanism is a cost-based model (CBO), which estimates I/O and CPU costs to determine the execution path; 1. Perform ANALYZETABLE regularly to ensure the accuracy of statistical information; 2. Indexes are not always used, such as querying large amounts of data or function operations may fail; 3. It is recommended to use EXPLAIN to view the execution plan, create overlay indexes, and avoid implicit type conversion; 4. The optimizer can be booted through USEINDEX or FORCEINDEX, but be cautious; 5. Rewriting the SQL structure and controlling the connection order can also affect the optimization results. Mastering these logic and combining tool analysis can help to optimize efficiently.
    Mysql Tutorial . Database 909 2025-07-08 02:56:01
  • Using JSON Data Type and Functions in MySQL 5.7 and Later
    Using JSON Data Type and Functions in MySQL 5.7 and Later
    MySQL5.7 natively supports JSON data types, improving the efficiency of processing unstructured data. 1. Use the JSON type to automatically verify the data format and provide special function operation content; 2. When querying, field values ??can be extracted through -> or JSON_EXTRACT(), supporting array element extraction; 3. Use functions such as JSON_SET(), JSON_REPLACE(), JSON_REMOVE() to modify data; 4. You can optimize the query performance of JSON fields by generating virtual columns and establishing indexes; 5. Although it is flexible, JSON type should not be abused, and it needs to be used in combination with actual scenarios.
    Mysql Tutorial . Database 312 2025-07-08 02:53:40
  • Using triggers for database automation in MySQL
    Using triggers for database automation in MySQL
    A trigger is an automatically executed database object in MySQL that is used to perform predefined SQL operations when a specific event occurs. It can automatically update timestamps, verify or record data changes, maintain redundant fields, implement cascading operations, etc. To create a trigger, you need to specify the trigger timing (BEFORE/AFTER), event type (INSERT/UPDATE/DELETE) and execution logic, such as automatically populating the created_at field with BEFOREINSERT. When using it, you should pay attention to problems such as debugging difficulties, performance impact, high maintenance costs and inapplicability to distributed systems. It is recommended to keep the logic simple and make comments. Common scenarios include recording modification logs, restricting illegal operations, synchronous update of statistics tables and automatic filling
    Mysql Tutorial . Database 412 2025-07-08 02:53:20
  • Grouping Data with GROUP BY and Aggregate Functions in MySQL
    Grouping Data with GROUP BY and Aggregate Functions in MySQL
    To extract summary information from the database, use GROUPBY and aggregate functions. GROUPBY can group data by field, and is often used in combination with aggregate functions such as SUM, COUNT, AVG, MAX, MIN, etc.; non-aggregated fields must appear in GROUPBY after SELECT; multi-field grouping is combined in order; HAVING is used to filter grouping results, such as filtering users with a total order amount of more than 1,000.
    Mysql Tutorial . Database 395 2025-07-08 02:52:01
  • Handling character sets and collations issues in MySQL
    Handling character sets and collations issues in MySQL
    Character set and sorting rules issues are common when cross-platform migration or multi-person development, resulting in garbled code or inconsistent query. There are three core solutions: First, check and unify the character set of database, table, and fields to utf8mb4, view through SHOWCREATEDATABASE/TABLE, and modify it with ALTER statement; second, specify the utf8mb4 character set when the client connects, and set it in connection parameters or execute SETNAMES; third, select the sorting rules reasonably, and recommend using utf8mb4_unicode_ci to ensure the accuracy of comparison and sorting, and specify or modify it through ALTER when building the library and table.
    Mysql Tutorial . Database 498 2025-07-08 02:51:00
  • Implementing Transactions and Understanding ACID Properties in MySQL
    Implementing Transactions and Understanding ACID Properties in MySQL
    MySQL supports transaction processing, and uses the InnoDB storage engine to ensure data consistency and integrity. 1. Transactions are a set of SQL operations, either all succeed or all fail to roll back; 2. ACID attributes include atomicity, consistency, isolation and persistence; 3. The statements that manually control transactions are STARTTRANSACTION, COMMIT and ROLLBACK; 4. The four isolation levels include read not committed, read submitted, repeatable read and serialization; 5. Use transactions correctly to avoid long-term operation, turn off automatic commits, and reasonably handle locks and exceptions. Through these mechanisms, MySQL can achieve high reliability and concurrent control.
    Mysql Tutorial . Database 308 2025-07-08 02:50:41
  • Designing a Robust MySQL Database Backup Strategy
    Designing a Robust MySQL Database Backup Strategy
    To design a reliable MySQL backup solution, 1. First, clarify RTO and RPO indicators, and determine the backup frequency and method based on the acceptable downtime and data loss range of the business; 2. Adopt a hybrid backup strategy, combining logical backup (such as mysqldump), physical backup (such as PerconaXtraBackup) and binary log (binlog), to achieve rapid recovery and minimum data loss; 3. Test the recovery process regularly to ensure the effectiveness of the backup and be familiar with the recovery operations; 4. Pay attention to storage security, including off-site storage, encryption protection, version retention policy and backup task monitoring.
    Mysql Tutorial . Database 648 2025-07-08 02:45:21

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