MySQL có nhiều chức năng tích hợp sẵn.
Tham chiếu này chứa chuỗi, số, ngày tháng và một số hàm nâng cao trong MySQL.
| Function |
Description |
| ASCII |
Returns the ASCII value for the specific character |
| CHAR_LENGTH |
Returns the length of a string (in characters) |
| CHARACTER_LENGTH |
Returns the length of a string (in characters) |
| CONCAT |
Adds two or more expressions together |
| CONCAT_WS |
Adds two or more expressions together with a separator |
| FIELD |
Returns the index position of a value in a list of values |
| FIND_IN_SET |
Returns the position of a string within a list of strings |
| FORMAT |
Formats a number to a format like "#,###,###.##", rounded to a
specified number
of decimal places |
| INSERT |
Inserts a string within a string at the specified position and for a certain
number of characters |
| INSTR |
Returns the position of the first occurrence of a string in another string |
| LCASE |
Converts a string to lower-case |
| LEFT |
Extracts a number of characters from a string (starting from left) |
| LENGTH |
Returns the length of a string (in bytes) |
| LOCATE |
Returns the position of the first occurrence of a substring in a string |
| LOWER |
Converts a string to lower-case |
| LPAD |
Left-pads a string with another string, to a certain length |
| LTRIM |
Removes leading spaces from a string |
| MID |
Extracts a substring from a string (starting at any position) |
| POSITION |
Returns the position of the first occurrence of a substring in a string |
| REPEAT |
Repeats a string as many times as specified |
| REPLACE |
Replaces all occurrences of a substring within a string, with a new
substring |
| REVERSE |
Reverses a string and returns the result |
| RIGHT |
Extracts a number of characters from a string (starting from right) |
| RPAD |
Right-pads a string with another string, to a certain length |
| RTRIM |
Removes trailing spaces from a string |
| SPACE |
Returns a string of the specified number of space characters |
| STRCMP |
Compares two strings |
| SUBSTR |
Extracts a substring from a string (starting at any position) |
| SUBSTRING |
Extracts a substring from a string (starting at any position) |
| SUBSTRING_INDEX |
Returns a substring of a string before a specified number of
delimiter occurs |
| TRIM |
Removes leading and trailing spaces from a string |
| UCASE |
Converts a string to upper-case |
| UPPER |
Converts a string to upper-case |
| Function |
Description |
| ABS |
Returns the absolute value of a number |
| ACOS |
Returns the arc cosine of a number |
| ASIN |
Returns the arc sine of a number |
| ATAN |
Returns the arc tangent of one or two numbers |
| ATAN2 |
Returns the arc tangent of two numbers |
| AVG |
Returns the average value of an expression |
| CEIL |
Returns the smallest integer value that is >= to a number |
| CEILING |
Returns the smallest integer value that is >= to a number |
| COS |
Returns the cosine of a number |
| COT |
Returns the cotangent of a number |
| COUNT |
Returns the number of records returned by a select query |
| DEGREES |
Converts a value in radians to degrees |
| DIV |
Used for integer division |
| EXP |
Returns e raised to the power of a specified number |
| FLOOR |
Returns the largest integer value that is <= to a number |
| GREATEST |
Returns the greatest value of the list of arguments |
| LEAST |
Returns the smallest value of the list of arguments |
| LN |
Returns the natural logarithm of a number |
| LOG |
Returns the natural logarithm of a number, or the logarithm of a number to a
specified base |
| LOG10 |
Returns the natural logarithm of a number to base 10 |
| LOG2 |
Returns the natural logarithm of a number to base 2 |
| MAX |
Returns the maximum value in a set of values |
| MIN |
Returns the minimum value in a set of values |
| MOD |
Returns the remainder of a number divided by another number |
| PI |
Returns the value of PI |
| POW |
Returns the value of a number raised to the power of another number |
| POWER |
Returns the value of a number raised to the power of another number |
| RADIANS |
Converts a degree value into radians |
| RAND |
Returns a random number |
| ROUND |
Rounds a number to a specified number of decimal places |
| SIGN |
Returns the sign of a number |
| SIN |
Returns the sine of a number |
| SQRT |
Returns the square root of a number |
| SUM |
Calculates the sum of a set of values |
| TAN |
Returns the tangent of a number |
| TRUNCATE |
Truncates a number to the specified number of decimal places |
| Function |
Description |
| ADDDATE |
Adds a time/date interval to a date and then returns the date |
| ADDTIME |
Adds a time interval to a time/datetime and then returns the time/datetime |
| CURDATE |
Returns the current date |
| CURRENT_DATE |
Returns the current date |
| CURRENT_TIME |
Returns the current time |
| CURRENT_TIMESTAMP |
Returns the current date and time |
| CURTIME |
Returns the current time |
| DATE |
Extracts the date part from a datetime expression |
| DATEDIFF |
Returns the number of days between two date values |
| DATE_ADD |
Adds a time/date interval to a date and then returns the date |
| DATE_FORMAT |
Formats a date |
| DATE_SUB |
Subtracts a time/date interval from a date and then returns the date |
| DAY |
Returns the day of the month for a given date |
| DAYNAME |
Returns the weekday name for a given date |
| DAYOFMONTH |
Returns the day of the month for a given date |
| DAYOFWEEK |
Returns the weekday index for a given date |
| DAYOFYEAR |
Returns the day of the year for a given date |
| EXTRACT |
Extracts a part from a given date |
| FROM_DAYS |
Returns a date from a numeric datevalue |
| HOUR |
Returns the hour part for a given date |
| LAST_DAY |
Extracts the last day of the month for a given date |
| LOCALTIME |
Returns the current date and time |
| LOCALTIMESTAMP |
Returns the current date and time |
| MAKEDATE |
Creates and returns a date based on a year and a number of days value |
| MAKETIME |
Creates and returns a time based on an hour, minute, and second value |
| MICROSECOND |
Returns the microsecond part of a time/datetime |
| MINUTE |
Returns the minute part of a time/datetime |
| MONTH |
Returns the month part for a given date |
| MONTHNAME |
Returns the name of the month for a given date |
| NOW |
Returns the current date and time |
| PERIOD_ADD |
Adds a specified number of months to a period |
| PERIOD_DIFF |
Returns the difference between two periods |
| QUARTER |
Returns the quarter of the year for a given date value |
| SECOND |
Returns the seconds part of a time/datetime |
| SEC_TO_TIME |
Returns a time value based on the specified seconds |
| STR_TO_DATE |
Returns a date based on a string and a format |
| SUBDATE |
Subtracts a time/date interval from a date and then returns the date |
| SUBTIME |
Subtracts a time interval from a datetime and then returns the time/datetime |
| SYSDATE |
Returns the current date and time |
| TIME |
Extracts the time part from a given time/datetime |
| TIME_FORMAT |
Formats a time by a specified format |
| TIME_TO_SEC |
Converts a time value into seconds |
| TIMEDIFF |
Returns the difference between two time/datetime expressions |
| TIMESTAMP |
Returns a datetime value based on a date or datetime value |
| TO_DAYS |
Returns the number of days between a date and date "0000-00-00" |
| WEEK |
Returns the week number for a given date |
| WEEKDAY |
Returns the weekday number for a given date |
| WEEKOFYEAR |
Returns the week number for a given date |
| YEAR |
Returns the year part for a given date |
| YEARWEEK |
Returns the year and week number for a given date |
| Function |
Description |
| BIN |
Returns a binary representation of a number |
| BINARY |
Converts a value to a binary string |
| CASE |
Goes through conditions and return a value when the first condition is
met |
| CAST |
Converts a value (of any type) into a specified datatype |
| COALESCE |
Returns the first non-null value in a list |
| CONNECTION_ID |
Returns the unique connection ID for the current connection |
| CONV |
Converts a number from one numeric base system to another |
| CONVERT |
Converts a value into the specified datatype or character set |
| CURRENT_USER |
Returns the user name and host name for the MySQL account that the server
used to authenticate the current client |
| DATABASE |
Returns the name of the current database |
| IF |
Returns a value if a condition is TRUE, or another value if a condition is FALSE |
| IFNULL |
Return a specified value if the expression is NULL, otherwise return the
expression |
| ISNULL |
Returns 1 or 0 depending on whether an expression is NULL |
| LAST_INSERT_ID |
Returns the AUTO_INCREMENT id of the last row that has been inserted in a table |
| NULLIF |
Compares two expressions and returns NULL if they are equal. Otherwise, the
first expression is returned |
| SESSION_USER |
Returns the current MySQL user name and host name |
| SYSTEM_USER |
Returns the current MySQL user name and host name |
| USER |
Returns the current MySQL user name and host name |
| VERSION |
Returns the current version of the MySQL database |
