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MySQL- functies


MySQL heeft veel ingebouwde functies.

Deze referentie bevat string, numeriek, datum en enkele geavanceerde functies in MySQL.


MySQL-tekenreeksfuncties

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


Numerieke MySQL-functies

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

MySQL-datumfuncties

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

Geavanceerde MySQL-functies

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