The smart IT organization should be proactive and prepare now for larger data volumes and more analytics activity by tuning their big data application for high performance
MySQL :: MySQL 5.0 Reference Manual :: 12.7 Date and Time Functions
Date arithmetic also can be performed using INTERVAL together with the + or - operator: date + INTERVAL expr unit date - INTERVAL expr unit INTERVAL expr unit is permitted on either side of the + operator if the expression on the other side is a date or datetime value. Since the last login is to be updated only if an hour or more has passed since the last login this was a big problem!The problem is that PHP takes DST into account and MySQL does not (as far as I know) and I was entering the time using MySQL's NOW() function and then comparing the value returned by PHP's time() function.A very simple solution to this is the following
So if an application always inputs time as CST (no matter when inputted throughout the year), the time can then be associated with UTC -6 and UTC -5 applied to it, giving CDT but never mentioning CST or CDT as both are not supported within oracle
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If you do not specify indexes in the bind call, and two different binds in a statement specify tables that contain a different number of elements, then the number of elements actually used is the minimum number between all tables. For example, after creating this procedure, you could make the following call: exec('create table acct(c1 integer)'); You could even call this procedure remotely, as shown in the following example
Dates in Oracle Dates part of SQL for Web Nerds by Philip Greenspun, updated June 13, 2003 When representing date-time information in Oracle it becomes absolutely critical to know with which version of the Oracle server you are working. These are cleaner and more powerful than the older Oracle-specific way of doing things and further will make it easier to port your application to another RDBMS if necessary
The article is intended for SQL coders, who for might be not be using analytic functions due to unfamiliarity with its cryptic syntax or uncertainty about its logic of operation. What about when you have a data set that contains records with timestamps and you would like to roll them up to the second and then look at a sliding window to find, say the busiest 5 minutes of the day? It is trivial to create the query to aggregate the data into per-second blocks but I cannot figure out the syntax to put a window around it
SQL Functions
Table 3-10 The Format Models with the ROUND Date Function Formal Model Rounding Unit CC or SCC Century YYYY, SYYYY, YEAR, SYEAR, YYY, YY, Y Year (rounds up on July 1) IYYY, IYY, IY, I ISO Year Q Quarter (rounds up in the sixteenth day of the second month of the quarter) MONTH, MON, MM, RM Month (rounds up on the sixteenth day) WW Same day of the week as the first day of the year IW Same day of the week as the first day of the ISO year W Same day of the week as the first day of the month DDD, DD, J Day DAY, DY, D Starting day of the week. Oracle Lite evaluates each search value only before comparing it to the expression, rather than evaluating all search values before comparing any of them with the expression
Think twice, for example, before reading a TIMESTAMP value from a table into a DATE variable, because you might lose information (in this case, the fractional seconds and perhaps the time zone). Unlike strings and numbers, dates are quite complicated: not only are they highly formatted data, but there are also many rules for determining valid values and valid calculations (leap days and years, daylight saving time changes, national and company holidays, date ranges, and so on)
SQL FAQ - Oracle FAQ
COMMIT - save work done SAVEPOINT - identify a point in a transaction to which you can later roll back ROLLBACK - undo the modification I made since the last COMMIT SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use SET ROLE - set the current active roles DML are not auto-commit. If you include the SAMPLE clause within a multi-table or remote query, you will get a parse error or "ORA-30561: SAMPLE option not allowed in statement with multiple table references"
If the format parameter is omitted, the TRUNC function will truncate the date to the day value, so that any hours, minutes, or seconds will be truncated off
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