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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, 404🔥, 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, 350🔥, 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, 338🔥, 0💬

LEAD() - N-Row after Current Row within Window
How to evaluate a field expression on n-row after the current row in the current result set window using the LEAD() function? LEAD(exp, n, default) is a MySQL built-in window function that evaluates a field expression on n-row after the current row in the current result set window. For example: SELE...
2024-09-28, 335🔥, 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, 333🔥, 0💬

NTILE() - Dividing Window into N Tiles
How to divid result set window into N tiles and return the tile position using the NTILE() function? NTILE(n) is a MySQL built-in window function that divides result set window into n tiles and returns the tile position of the current row. For example: SELECT help_topic_id AS tip, help_category_id A...
2024-09-12, 521🔥, 0💬

NTH_VALUE() - N-th Value of Result Set Window
How to obtain the n-th value of a field expression in the current result set window using the NTH_VALUE() function? NTH_VALUE(exp, n) is a MySQL built-in window function that returns the n-th value of a field expression in the current result set window. For example: SELECT help_topic_id AS tip, help...
2024-09-12, 376🔥, 0💬

PERCENT_RANK() - Rank Percentage of Sorted Values
How to calculate the rank percentage of the sorting field expression in the current result set window using the PERCENT_RANK() function? PERCENT_RANK(n) is a MySQL built-in window function that calculates the rank percentage of the sorting field expression in the current result set window. For examp...
2024-09-12, 359🔥, 0💬

RANK() - Vale Rank of Sorted Values
How to calculate the value rank of the sorting field expression in the current result set window using the RANK() function? RANK(n) is a MySQL built-in window function that calculates the value rank of the sorting field expression in the current result set window. For example: SELECT help_topic_id A...
2024-09-12, 358🔥, 0💬

ROW_NUMBER() - Row Position in Result Set Window
How to obtain the row position of the current row in the current result set window using the ROW_NUMBER() function? ROW_NUMBER(n) is a MySQL built-in window function that returns the row position of the current row in the current result set window. For example: SELECT help_topic_id AS tic, help_cate...
2024-09-12, 348🔥, 0💬

BENCHMARK() - Repeating Expression Evaluation
How to evaluate an expression repeatedly for benchmark testing using the BENCHMARK() function? BENCHMARK(count, exp) is a MySQL built-in function that evaluates an expression repeatedly for benchmark testing and returns 0. For example: SELECT BENCHMARK(1000000, AES_ENCRYPT('hello','goodbye') );-- +-...
2024-07-17, 463🔥, 2💬

💬 2024-07-17 Iqra Technology: This is a great overview of the `BENCHMARK()` function in MySQL! Your examples clearly illustrate how it can be used to evaluate...

CURRENT_ROLE() - Current Role of Logged-In User
How to obtain the current role of the logged-in user using the CURRENT_ROLE() function? CURRENT_ROLE() is a MySQL built-in function that returns the current role of the logged-in user. For example: SELECT CURRENT_ROLE(); -- +----------------+ -- | CURRENT_ROLE() | -- +----------------+ -- | NONE | -...
2024-07-15, 1353🔥, 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, 463🔥, 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, 450🔥, 0💬

CONNECTION_ID() - Thread ID of Current Connection
How to obtain the connection ID of the current connection using the CONNECTION_ID() function? CONNECTION_ID() is a MySQL built-in function that returns the connection ID of the current connection. The connection ID is also referred as thread ID or process ID. For example: SELECT CONNECTION_ID(); -- ...
2024-07-15, 412🔥, 0💬

Removed: PASSWORD() - Generating Password Hash
How to convert a password into a hash value with the default hashing algorithm using the PASSWORD() function? PASSWORD(password) is a MySQL built-in function that converts a password into a hash value with the default hashing algorithm. Note that PASSWORD() is no longer supported. It was: Introduced...
2024-05-15, 544🔥, 0💬

Window Functions
What Are Window Functions? A Window Function is a function that can perform calculations over a window of rows referenced from the current row in query result. A window function is called with a OVER clause in the following syntax: window_function(...) OVER window where window is one of the followin...
2024-05-15, 508🔥, 0💬

MySQL Functions on Result Set Windows
Where to find reference information and tutorials on MySQL database functions on Result Set Windows? I want to know how to use FIRST_VALUE(), ROW_NUMBER() and other window functions. Here is a collection of reference information and tutorials on MySQL database functions on Result Set Windows compile...
2024-05-15, 465🔥, 0💬

CUME_DIST() - Cumulative Distribution of Sorted Values
How to calculate the cumulative distribution of the sorting field expression in the current result set window using the CUME_DIST() function? CUME_DIST() is a MySQL built-in window function that calculates the cumulative distribution of the sorting field expression in the current result set window. ...
2024-05-15, 441🔥, 0💬

Removed: ENCRYPT() - Unix crypt() Hash Algorithm
How to generate a hash value with the Unix crypt() algorithm using the ENCRYPT() function? ENCRYPT(bytes) is a MySQL built-in function that generates a hash value with the Unix crypt() algorithm. Note that ENCRYPT() is no longer supported. It was: Introduced MySQL 4.0. Removed in MySQL 8.0. Related ...
2024-05-15, 422🔥, 0💬

RELEASE_LOCK() - Release Lock Instance
How to release an instance of a given lock associated with the current connection session using the RELEASE_LOCK() function? RELEASE_LOCK(lock) is a MySQL built-in function that releases an instance of a given lock associated with the current connection session. It returns 1 if released Successfully...
2023-12-20, 411🔥, 0💬

RELEASE_ALL_LOCKS() - Release All Locks
How to release all locks associated with the current connection session using the RELEASE_ALL_LOCKS() function? RELEASE_ALL_LOCKS(lock) is a MySQL built-in function that releases all locks associated with the current connection session. It returns the number of locks released. For example: SELECT GE...
2023-12-20, 458🔥, 0💬

IS_USED_LOCK() - Checking Lock Owner
How to check the owner of a user defined lock using the IS_USED_LOCK() function? IS_USED_LOCK(lock) is a MySQL built-in function that returns the connection id the lock associated with if the lock is in use, NULL otherwise. For example: SELECT GET_LOCK('MyLock', 60), IS_USED_LOCK('MyLock'); -- +----...
2023-12-20, 403🔥, 0💬

GET_LOCK() - Requesting User Defined Lock
How to request a user defined lock using the GET_LOCK() function? GET_LOCK(lock, timeout) is a MySQL built-in function that tries to obtain a user defined lock within a timeout period. It returns 1 if successful, 0 if failed. For example: SELECT GET_LOCK('MyLock', 60), IS_FREE_LOCK('MyLock'), IS_USE...
2023-12-20, 522🔥, 0💬

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