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MySQL Error 1215: Cannot add foreign key constraint
...uessing that Clients.Case_Number and/or Staff.Emp_ID are not exactly the same data type as Clients_has_Staff.Clients_Case_Number and Clients_has_Staff.Staff_Emp_ID.
Perhaps the columns in the parent tables are INT UNSIGNED?
They need to be exactly the same data type in both tables.
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How was the first compiler written?
...t lists them with the matching assembly instructions, and hand-determining memory addresses/offsets for things like jumps.
The first programs were done in exactly this fashion - hand-written opcodes.
However, most of the time it's simpler to use an assembler to "compile" assembly code, which autom...
What is a clearfix?
Recently I was looking through some website's code, and saw that every <div> had a class clearfix .
9 Answers
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Concept behind these four lines of tricky C code
...representation uses binary exponent and mantissa, doubling the number increments the exponent by one. Your program does it precisely 771 times, so the exponent which started at 1075 (decimal representation of 10000110011) becomes 1075 + 771 = 1846 at the end; binary representation of 1846 is 1110011...
Initialize class fields in constructor or at declaration?
....
Prefer initialization in declaration if you don't have a constructor parameter that changes the value of the field.
If the value of the field changes because of a constructor parameter put the initialization in the constructors.
Be consistent in your practice (the most important rule).
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Check if element is visible in DOM
Is there any way that I can check if an element is visible in pure JS (no jQuery) ?
18 Answers
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Set keyboard caret position in html textbox
...ou wish:
function setCaretPosition(elemId, caretPos) {
var elem = document.getElementById(elemId);
if(elem != null) {
if(elem.createTextRange) {
var range = elem.createTextRange();
range.move('character', caretPos);
range.select();
}
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How do I calculate someone's age in Java?
I want to return an age in years as an int in a Java method.
What I have now is the following where getBirthDate() returns a Date object (with the birth date ;-)):
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What is the optimal length for user password salt? [closed]
...e size and security. Is a random 10 character salt enough? Or do I need something longer?
5 Answers
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Abstract Class vs Interface in C++ [duplicate]
...use an interface instead of an abstract class in C++? Could you give some examples?
5 Answers
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