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Technical Articles

Database

How to perform a search with regular expressions (regex) in SQL?

MySQL and MariaDB use REGEXP or RLIKE operators for regular matching, such as WHEREcolumn_nameREGEXP'^A'; 2. PostgreSQL uses ~ (case sensitive) and ~* (insensitive) operators to support full POSIX rules, such as WHEREcolumn_name~'^\d{3}-\d{3}-\d{4}$'; 3. Oracle and MySQL8.0 use REGEXP_LIKE functions, such as WHEREREGEXP_LIKE(column_name,'^john','i') to support flag bits; 4. SQLite does not support regular by default, and requires

Aug 11, 2025 pm 12:47 PM

How to create a view in SQL

The syntax for creating a view is the CREATEVIEWview_nameASSELECT statement; 2. The view does not store actual data, but is based on the real-time query results of the underlying table; 3. The view can be modified using CREATEORREPLACEVIEW; 4. The view can be deleted through DROPVIEW; 5. The view is suitable for simplifying complex queries, providing data access control, and maintaining interface consistency, but attention should be paid to performance and logic, and finally ends with a complete sentence.

Aug 11, 2025 pm 12:40 PM

sql view

How to compare two tables for differences in MySQL

To compare the differences between two tables in MySQL, different operations need to be performed according to the structure, data or both: 1. When comparing the table structure, use DESCRIBE or query INFORMATION_SCHEMA.COLUMNS to find columns that exist only in one table through UNIONALL and subqueries; 2. When comparing table data, use LEFTJOIN combined with ISNULL conditions to find rows that exist only in table1 or table2, and use UNIONALL to merge the results with UNIONALL; 3. When comparing rows with the same primary key but different data, use JOIN to connect the two tables and use NULL safe comparison operator to detect the difference in the values of each column; 4. You can first perform row count statistics checks and compare them through COUNT(*)

Aug 11, 2025 pm 12:14 PM

What is the 'score' in a Sorted Set?

ThescoreinaRedisSortedSetisanumericalvaluethatdeterminestheelement'spositionwithintheset.Unlikeregularsets,whichareunordered,SortedSetsusescorestomaintainanautomaticorderfromsmallesttolargest.Eachmemberisassociatedwithascore,enablingdynamicrankingand

Aug 11, 2025 am 11:55 AM

score

How to get the identity of the last inserted row in SQL?

InSQLServer,useSCOPE_IDENTITY()togetthelastinsertedidentityvaluewithinthesamescope,avoidingissueswithtriggers;2.InMySQL,useLAST_INSERT_ID()immediatelyafterINSERT,whichisconnection-specificandreliable;3.InPostgreSQL,usetheRETURNINGclauseintheINSERTsta

Aug 11, 2025 am 11:50 AM

sql Insert row

How do you perform pattern matching using the LIKE operator in SQL?

Use the LIKE operator to perform pattern matching in SQL. 1.% wildcards match any number of characters (including zeros), such as 'A%' to find strings starting with A; 2. The _wildcards match a single character, such as '_a%' to find strings with the second character a; 3. You can use wildcards in combination, such as 'J__n%' to find strings starting with J and the fourth bit n; 4. Pay attention to the difference in case sensitivity of different databases. MySQL and SQLServer are usually case-insensitive, and PostgreSQL distinguishes, and ILIKE is required to achieve indistinguishability; 5. Use ESCAPE keywords to escape special characters, such as '\%' to match the percent sign of the literal, and '\_' to match the underscore, so as to accurately find % containing %

Aug 11, 2025 am 11:48 AM

Connecting to MongoDB with Python

Install PyMongo: Use pipinstallpymongo to install the driver. 2. Connect to local MongoDB: Connect through MongoClient('mongodb://localhost:27017/'), the default URI is the local instance. 3. Connect to MongoDBAtlas: Use an SRV connection string containing the username, password and cluster URL, such as mongodb srv://user:pass@cluster.host/dbname. 4. Security configuration: Set a network whitelist in Atlas and store credentials through environment variables. 5. Perform CRUD operation: Use insert_one

Aug 11, 2025 am 11:32 AM

Optimizing MySQL for High-Throughput Message Queues

TouseMySQLefficientlyasamessagequeueunderhigh-throughputworkloads,followthesesteps:1)UseInnoDBwithproperindexing—createcompositeindexesonselectivefieldslikequeue_nameandstatus,avoidexcessiveindexestomaintaininsertperformance.2)Usebatchoperations—inse

Aug 11, 2025 am 11:26 AM

An Introduction to MongoDB Atlas

MongoDBAtlasistheofficialfullymanagedclouddatabaseserviceforMongoDBthatsimplifiesdeployment,management,andscalingofdatabases.1.Itenablesone-clickdeploymentacrossAWS,GoogleCloud,orAzurewithafreetieravailableforlearningandsmallprojects.2.Securityfeatur

Aug 11, 2025 am 11:10 AM

nosql database

How to use ROW_NUMBER() in SQL?

ROW_NUMBER() is a window function in SQL for assigning unique serial numbers, suitable for ranking, paging, and deduplication. 1. The basic usage is ROW_NUMBER()OVER(ORDERBYcolumn_name), which can be sorted and numbered in the specified column; 2. Support grouping numbering, and the syntax is ROW_NUMBER()OVER(PARTITIONBYgroup_columnORDERBYorder_column), such as order amounts sorted and numbered after grouping by sales personnel; 3. It is often used to deduplicate, keep the first record in each group, such as grouping through mailbox and keeping the earliest registration record; 4. Paging query can be implemented to obtain specific page data through the number range; 5

Aug 11, 2025 am 11:07 AM

How to use variables in phpMyAdmin query

UseMySQLuser-definedvariables(e.g.,@variable)tostoreandreusevaluesinphpMyAdmin;2.RunmultiplestatementstogetherinoneSQLwindowwithsemicolons,ensuring"Allowmultiplequeries"isenabled;3.Optionallyusevariablesinpreparedstatementsfordynamicqueries

Aug 11, 2025 am 10:43 AM

variable

How to back up a database in MySQL

Using mysqldump is the most common and effective way to back up MySQL databases. It can generate SQL scripts containing table structure and data. 1. The basic syntax is: mysqldump-u[user name]-p[database name]>backup_file.sql. After execution, enter the password to generate a backup file. 2. Back up multiple databases with --databases option: mysqldump-uroot-p--databasesdb1db2>multiple_dbs_backup.sql. 3. Back up all databases with --all-databases: mysqldump-uroot-p

Aug 11, 2025 am 10:40 AM

mysql database backup

Navicat alternatives: security options

Navicatalternativesofferrobustsecurityoptions:1)DBeaverprovidesSSL/TLSencryption,RBAC,andauditlogging;2)HeidiSQLsupportsSSL/TLSwithbasicaccesscontrol;3)pgAdminoffersSSL/TLS,RBAC,detailedauditlogging,androw-levelsecurity.

Aug 11, 2025 am 10:34 AM

Security Options Database Tools

phpMyAdmin set a primary key

TosetaprimarykeyinphpMyAdmin,firstdetermineifyou'recreatinganewtableormodifyinganexistingone.1.Whencreatingatable,entercolumndetailsandcheckthe"Primary"checkboxforthedesiredcolumn,optionallyenabling"A_I"forauto-increment.2.Foranex

Aug 11, 2025 am 10:33 AM