General MySQL Oracle SQL Server

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What Is a SELECT Query Statement in MySQL
What Is a SELECT Query Statement in MySQL? The SELECT statement is also called the query statement. It is the most frequently used SQL statement in any database application. A SELECT statement allows you to retrieve data from one or more tables or views, with different selection criteria, grouping c... 2017-11-05, 2379🔥, 0💬

Selecting Columns in a Query in MySQL
How To Select Some Columns from a Table in MySQL? If you want explicitly tell the query to return some columns, you can specify the column names in the SELECT clause. The following select statement returns only two columns, "id" and "url" from the table "fyi_links": mysql&gt; SELECT id, url FROM... 2017-11-05, 2377🔥, 0💬

Using LIKE Conditions in MySQL
How To Use LIKE Conditions in MySQL? A LIKE condition is also called pattern patch. There are 3 main rules on using LIKE condition: '_' is used in the pattern to match any one character. '%' is used in the pattern to match any zero or more characters. ESCAPE clause is used to provide the escape char... 2018-03-24, 2372🔥, 0💬

Running MySQL Server on a Specific Port in MySQL
How To Run MySQL Server on a Different Port in MySQL? By default, MySQL will listen at port number 3306 for any client connections. But you can change this by starting the server with "--port=portNumber" option. The tutorial exercise shows you how to start the server to listen to a different port nu... 2017-11-29, 2369🔥, 0💬

Using Group Functions in the ORDER BY Clause in MySQL
Can Group Functions Be Used in the ORDER BY Clause in MySQL? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many links were created in each year in each tag. The group output is sorted by the c... 2017-12-31, 2350🔥, 0💬

SESSION_USER() - Synonym for USER()
What's the difference between SESSION_USER() and USER() functions? SESSION_USER() is a synonym for the USER() function. Related MySQL functions: USER() - Login Name of Current User SESSION_USER() - Synonym for USER() SYSTEM_USER() - Synonym for USER() CURRENT_USER() - Authentication Name of Current ... 2025-01-07, 2345🔥, 0💬

JSON_VALID() - Validating JSON Value
How to verify if value is a JSON (JavaScript Object Notation) value using the JSON_VALID() function? JSON_VALID(val) is a MySQL built-in function that returns 1 if the given value is a valid JSON value. For example: SELECT JSON_VALID('hello'), JSON_VALID('"hello"'); -- +---------------------+------- ... 2023-12-17, 2344🔥, 0💬

MySQL Functions for Miscellaneous Purposes
Where to find reference information and tutorials on MySQL database functions for Miscellaneous Purposes? I want to know how to use CAST(), SLEEP() and other miscellaneous functions. Here is a collection of reference information and tutorials on MySQL database functions for Miscellaneous Purposes co... 2026-03-22, 2330🔥, 0💬

Inserting Rows with a SELECT Statement in MySQL
How To Insert Multiple Rows with a SELECT Statement in MySQL? If want to insert rows into a table based on data rows from other tables, you can use a sub-query inside the INSERT statement as shown in the following script example: &lt;?php include "mysql_connection.php"; $sql = "INSERT INTO fyi_l... 2017-09-20, 2323🔥, 0💬

DENSE_RANK() - Density Rank of Sorted Values
How to calculate the density rank of the sorting field expression in the current result set window using the DENSE_RANK() function? DENSE_RANK() is a MySQL built-in window function that calculates the density rank of the sorting field expression in the current result set window. For example: SELECT ... 2024-09-28, 2179🔥, 0💬

JSON_STORAGE_FREE() - Free Space in JSON Value
How to obtain the free space size in a JSON table column using the JSON_STORAGE_FREE() function? JSON_STORAGE_FREE(json) is a MySQL built-in function that returns the free space size in a JSON table column. Free space occurs when JSON table column is partially updated with less data. For example: CR... 2024-12-18, 2114🔥, 0💬

FORMAT_PICO_TIME() - Formatting Picoseconds in Readable Units
How to format a number of picoseconds in a human-readable unit using the FORMAT_PICO_TIME() function? FORMAT_PICO_TIME(con) is a MySQL built-in function that converts a number of picoseconds in a human-readable unit of ps, ns, ms, s, min, h, or d. For example: SELECT FORMAT_PICO_TIME(9), FORMAT_PICO... 2025-09-24, 2113🔥, 0💬

INET6_NTOA() - IPv6 Address Number to String
How to convert an IPv6 address from number format to string using the INET6_NTOA() function? INET6_NTOA(int) is a MySQL built-in function that converts an IPv6 address from number format to string. For example: SET @ipv6 = UNHEX('FDFE0000000000005A55CAF FFEFA9089');SELECT HEX(@ipv6), INET6_NTOA(@ipv... 2026-02-02, 2100🔥, 0💬

JSON_SCHEMA_VALID() - JSON Schema Validation
How to validate a JSON value against a JSON schema using the JSON_SCHEMA_VALID() function? JSON_SCHEMA_VALID(schema, json) is a MySQL built-in function that validates a JSON value against a given JSON schema. For example: SET @schema = '{ "id": "http://json-schema.org/geo", "$schema": "http://json-s... 2024-11-23, 2048🔥, 0💬

UNCOMPRESSED_LENGTH() - Uncompressed Data Length
How to calculate the original data length of a compressed byte string using the UNCOMPRESSED_LENGTH() function? UNCOMPRESSED_LENGTH(str) is a MySQL built-in function that returns the original data length of a given compressed byte string. For example: SET @bin = x'37000000789C738BF44C4ECD2B49 2DD24BC... 2024-12-18, 2041🔥, 0💬

LAG() - N-Row before Current Row within Window
How to evaluate a field expression on n-row before the current row in the current result set window using the LAG() function? LAG(exp, n, default) is a MySQL built-in window function that evaluates a field expression on n-row before the current row in the current result set window. For example: SELE... 2024-09-28, 2017🔥, 0💬

MySQL Functions on Character String Values
Where to find reference information and tutorials on MySQL database functions on string values? I want to know how to use SUBSTRING(), REPLACE() and other character string related functions. Here is a collection of reference information and tutorials on MySQL database functions on string values comp... 2023-11-10, 1953🔥, 0💬

VALUES() - Column Value for "ON DUPLICATE KEY UPDATE"
How to obtain the inserting value of given column in the "ON DUPLICATE KEY UPDATE" clause using the VALUES() function? VALUES(col) is a MySQL built-in function that returns the inserting value of a given column and use it in the "ON DUPLICATE KEY UPDATE" clause. For example: CREATE TABLE MyTable (id... 2025-10-24, 1945🔥, 0💬

JSON_QUOTE() - Quoting JSON String
How to convert a regular character string into a JSON (JavaScript Object Notation) string using the JSON_QUOTE() function? JSON_QUOTE(str) is a MySQL built-in function that converts a regular character string into a JSON string by quoting the string with double quotes. It replaces the double-quote c... 2023-12-10, 1904🔥, 0💬

FIRST_VALUE() - First Value of Result Set Window
How to obtain the first value of a field expression in the current result set window using the FIRST_VALUE() function? FIRST_VALUE(exp) is a MySQL built-in window function that returns the first value of a field expression in the current result set window. For example: SELECT help_topic_id AS tip, h... 2024-09-28, 1888🔥, 0💬

MySQL Functions on System Information
Where to find reference information and tutorials on MySQL database functions on System Information? I want to know how to use DATABASE(), VERSION() and other functions. Here is a collection of reference information and tutorials on MySQL database functions on System Information compiled by FYIcente... 2024-07-15, 1833🔥, 0💬

LAST_VALUE() - Last Value of Result Set Window
How to obtain the last value of a field expression in the current result set window using the LAST_VALUE() function? LAST_VALUE(exp) is a MySQL built-in window function that returns the last value of a field expression in the current result set window. For example: SELECT help_topic_id AS tip, help_... 2024-09-28, 1830🔥, 0💬

Removed: DES_ENCRYPT() - DES Data Encryption
How to encrypt data with the DES (Data Encryption Standard) algorithm using the DES_ENCRYPT() function? DES_ENCRYPT(clear, key) is a MySQL built-in function that encrypts data with the DES (Data Encryption Standard) algorithm. Note that DES_ENCRYPT() is no longer supported. It was: Introduced MySQL ... 2024-10-14, 1803🔥, 0💬

CRC32() - Cyclic Redundancy Check 32-Bit
How to calculate the 32-bit CRC (Cyclic Redundancy Check) value using the CRC32() function? CRC32(str) is a MySQL built-in function that calculates the 32-bit CRC (Cyclic Redundancy Check) value of a given character string and returns it as an integer. For example: SELECT CRC32('MySQL'), HEX(CRC32('... 2024-07-15, 1803🔥, 0💬

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General MySQL Oracle SQL Server