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SQL: How to properly check if a record exists
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It's better to use either of the following:
-- Method 1.
SELECT 1
FROM table_name
WHERE unique_key = value;
-- Method 2.
SELECT COUNT(1)
FROM table_name
WHERE unique_key = value;
The first alternative should give you no result or one result, the second count should be zero or one.
How old is...
How to make join queries using Sequelize on Node.js
...sted, but what it does is basically just aliasing all columns of the users table to make sure they are placed into the correct model when returned and not mixed up with the posts model
Other than that you'll notice that it does a JOIN instead of selecting from two tables, but the result should be t...
Too many 'if' statements?
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If you cannot come up with a formula, you can use a table for such a limited number of outcomes:
final int[][] result = new int[][] {
{ 0, 0, 1, 2 },
{ 0, 0, 2, 1 },
{ 2, 1, 3, 3 },
{ 1, 2, 3, 3 }
};
return result[one][two];
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What's faster, SELECT DISTINCT or GROUP BY in MySQL?
If I have a table
15 Answers
15
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Change the Right Margin of a View Programmatically?
... As per your NOTE: I have doubt. If the textview or a button is inside a table row? Then what should I use instead of Relative Layout, Table Layout?
– tejas
Jun 27 '13 at 4:19
1
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How to find all serial devices (ttyS, ttyUSB, ..) on Linux without opening them?
... entries for drivers and line disciplines in
this directory, as shown in Table 1-11.
Table 1-11: Files in /proc/tty
..............................................................................
File Content
drivers list of drivers and the...
WCF vs ASP.NET Web API [closed]
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this table is meaningless. "JQuery" (scare quotes for the capital J) is a protocol and/or format?
– hyankov
Sep 2 '17 at 18:39
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What can you use Python generator functions for?
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Real World Example
Let's say you have 100 million domains in your MySQL table, and you would like to update Alexa rank for each domain.
First thing you need is to select your domain names from the database.
Let's say your table name is domains and column name is domain.
If you use SELECT domai...
What is the difference between “text” and new String(“text”)?
...al is needed, use of this constructor is unnecessary since strings are immutable.
Related questions
Java Strings: “String s = new String(”silly“);”
Strings are objects in Java, so why don’t we use ‘new’ to create them?
What referential distinction means
Examine the follow...
Benefits of inline functions in C++?
...t chooses not to use it.
I could see a situation like this making a detectable difference:
inline int aplusb_pow2(int a, int b) {
return (a + b)*(a + b) ;
}
for(int a = 0; a < 900000; ++a)
for(int b = 0; b < 900000; ++b)
aplusb_pow2(a, b);
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