Funzioni MySQL
MySQL ha molte funzioni integrate.
Questo riferimento contiene stringhe, numeri, date e alcune funzioni avanzate in MySQL.
Funzioni di stringa 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 |
Funzioni numeriche MySQL
| 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 |
Funzioni di data MySQL
| 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 |
Funzioni avanzate di MySQL
| 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 or updated 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 |