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오라클 GROUP_ID() GROUP_ID() - grouping 할 때... group_id 를 숫자로 부여. - 음... 처음보지만 필요한 함수다. GROUP_ID() 의 형태 GROUP_ID distinguishes duplicate groups resulting from a GROUP BY sepcification. It is useful in filtering out duplicate groupings from the query result. It returns an Oracle NUMBER to uniquely identify duplicate groups. This function is applicable only in a SELECT statement that contains a GROUP..

STR_TO_DATE(), TIME_FORMAT(), UNIX_TIMESTAMP(), DATE_FORMAMT() 와 같은 날짜 함수에서 연, 월, 일등의 지정자로서는 아래와 같은 것들이 있다. The specifiers shown in the following table may be used in the format string. The % character is required before format specifier characters. The specifiers apply to other functions as well: STR_TO_DATE(), TIME_FORMAT(), UNIX_TIMESTAMP() Specifier Description %a Abbreviated weekday name (S..

MySQL 날짜 함수 같은데서 INTERVAL unit 으로 쓸 수 있는 것들 unit value Expected expr Format MICROSECOND MICROSECONDS SECOND SECONDS MINUTE MINUTES HOUR HOURS DAY DAYS WEEK WEEKS MONTH MONTHS QUARTER QUARTERS YEAR YEARS SECOND_MICROSECOND 'SECONDS.MICROSECONDS' MINUTE_MICROSECOND 'MINUTES:SECONDS.MICROSECONDS' MINUTE_SECOND 'MINUTES:SECONDS' HOUR_MICROSECOND 'HOURS:MINUTES:SECONDS.MICROSECONDS' HOUR_SECOND 'HOUR..

오라클 GREATEST() GREATEST returns the greatest of a list of one more expressions. Oracle Database uses the first expr to determine the return type. If the first expr is numeric, then Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that data type before the comparsion, and returns that data type. If the first expr is not numeric, th..

오라클 FLOOR() FLOOR(n) FLOOR returns the largest integer equal to or less than n. The number n can always be written as the sum of an integer k and a positive fraction f such that 0 SELECT FLOOR(15.7) FROM DUAL ; --> 15

오라클 FIRST() 이런 함수가 있는지 처음 알았다. FIRST AND LAST are very similar functions. Both are aggregate and analytic functions that operate on a set of values from a set of rows that rank as the FIRST or LAST with respect to a given sorting specification. If only row ranks as FIRST or LAST, then the aggregate operates on the set with only one element. If you omit the OVER caluse, then the FIRST and LAST fu..

오라클 EXTRACT() EXTRACT(datetime_filed FROM expr) datetime_field 에는 YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, TIMEZONE_HOUR, TIMEZONE_MINUTE, TIMEZONE_REGION, TIMEZONE_ABBR 이 올 수 있다. EXTRACT extracts and returns the value of a specified datetime field from a datetime or interval expression. The expr can be any expression that evaluates to a datetime or interval data type compatible with the request ..

오라클 EXP() 지수함수 정도 ? EXP returns a raised to the nth power, where e=2.71828183... . The function returns a value of the same type as the argument. This function takes as an argument any numeric data type or any nonnumeric data type that can be implicitly converted to a numeric data type. If the argument is BINARY_FLOAT, then the function returns BINARY_DOUBLE. Otherwise the functionk returns the ..