Database Administration Questions

Error-first callbacks are used to pass errors and data as well. You have to pass the error as the first parameter, and it has to be checked to see if something went wrong. Additional arguments are used to pass data.

fs.readFile(filePath, function(err, data) {
if (err) {
// handle the error, the return is important here
// so execution stops here
return console.log(err)
}
// use the data object
console.log(data)
})

Immutable classes are Java classes whose objects can not be modified once created. Any modification in Immutable object result in new object. For example is String is immutable in Java. Mostly Immutable are also final in Java, in order to prevent sub class from overriding methods in Java which can compromise Immutability. You can achieve same functionality by making member as non final but private and not modifying them except in constructor.

This is only possible when that doctor is boy's mother.

Two main measures for the efficiency of an algorithm are Time and Space.

The network layer concerns with the packets. It brings the packets from the source to the destination.

The sentence which contains both an adverb and a conjunction is "Adam crept silently up the stairs, but couldn't slow his heartbeat."

Here, Adverb - Silently and Conjunction - But.

High level data models provide the concepts that are close to the way many users perceive data

Answer 1)  

1/3 x (54 x 150 + 60 x 300 + 36 x 450)

= 1/3 x 42300

= 14100.

Answer 2)

Required ratio of chairs = 64 x 450 + 56 x 50036 x 450 + 44 x 500

= 56800/38200

= 284/191.

Answer 3)

Required number of chairs =  35 x 12100 x 50000
= 3600.