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daily 06/30/2015

    • We were defeated by one thing only – by the inferior science of our enemies. I repeat – by the inferior science of our enemies.
    • Malvar’s leadership had been responsible, more than any other single factor, for the efficiency and power of our weapons.
    • “Frankly, gentlemen,” said Norden, “I doubt it. Our existing weapons have practically reached finality. I don’t wish to criticize my predecessor, or the excellent work done by the Research Staff in the last few generations, but do you realize that there has been no basic change in armaments for over a century?
    • And to add insult to injury, the JSF flier discovered he couldn’t even comfortably move his head inside the radar-evading jet’s cramped cockpit. “The helmet was too large for the space inside the canopy to adequately see behind the aircraft.” That allowed the F-16 to sneak up on him.
    • The last time dog fighting was considered obsolete was Vietnam. Many pilots died because of that thinking.
    • Perhaps you have a situation where you only want to produce a report when a set of circumstances arise.
    • If they forgot to submit a batch of orders a manager would want to know this and resolve quickly. The time a batch is submitted is stored in a submitted_date column. A select statement looking for null values in this column would give you one or more rows when this exception occurred.
    • So how could we automate this query and only send an email to the manager when a clerk did not submit their orders? To accomplish this task we are going to use the Row Count variable and If Condition Activity.
    • Of course the real problem with this query is the sales data. All rows of the sales table will be fetched back to Intelligence Central, and then many will simply be discarded because they are excluded by the join to the customer data. Depending upon how many years of sales records are kept, together with the volume of sales annually, this table could potentially contain tens of millions of rows in a real production environment.
    • Therefore, adding filters directly to the sales table will make a huge difference to the performance of this query. This revised edition adds a country name filter directly to the sales table:
    • In a normal RDBMS, adding the same WHERE clause condition to multiple tables is redundant because the relational join will naturally propagate restrictions on one table to each other table in the query.

Posted from Diigo. The rest of my favorite links are here.

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