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MySQL 'create schema' and 'create database' - Is there any difference
...asn't been allocated to any particular schema, you can do something like:
SELECT *
FROM your_table
which is equivalent to:
SELECT *
FROM dbo.your_table
Now, SQL server allows the creation of different schema, which gives you the possibility of grouping tables that share a similar purpose. That...
Do I need to create indexes on foreign keys on Oracle?
...ance of an index may be unacceptable.
Most salient here would seem to be selectivity: if the values in the index would be highly duplicated then it may give better performance to drop the index (if possible) and allow a table scan.
...
How to select the first element with a specific attribute using XPath
The XPath bookstore/book[1] selects the first book node under bookstore .
9 Answers
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How do MySQL indexes work?
...be faster to go through the pages one by one (in a database, this is "poor selectivity").
For a 10-page book, it makes no sense to make an index, as you may end up with a 10-page book prefixed by a 5-page index, which is just silly - just scan the 10 pages and be done with it.
The index also needs t...
OR is not supported with CASE Statement in SQL Server
...sions anywhere in the SQL queries. CASE expressions can be used within the SELECT statement, WHERE clauses, Order by clause, HAVING clauses, Insert, UPDATE and DELETE statements.
A CASE expression has the following two formats:
Simple CASE expression
CASE expression
WHEN expression1 THEN Result1...
What is a word boundary in regex?
...oundary, in most regex dialects, is a position between \w and \W (non-word char), or at the beginning or end of a string if it begins or ends (respectively) with a word character ([0-9A-Za-z_]).
So, in the string "-12", it would match before the 1 or after the 2. The dash is not a word character.
...
Is there a ternary conditional operator in T-SQL?
...
Use case:
select *
from table
where isExternal = case @type when 2 then 1 else 0 end
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How can I get enum possible values in a MySQL database?
... This solution works on codeigniter github.com/thiswolf/codeigniter-enum-select-boxes
– You Know Nothing Jon Snow
Jul 7 '13 at 16:28
3
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How can I get WebStorm to recognize Jasmine methods?
...ed JS library stubs in Webstorm/PHPStorm/Idea
Open File > Settings...
Select Languages & Frameworks > JavaScript > Libraries
Click on Download...
Swich to TypeScript community stubs
Find karma-jasmine (originally under the name jasmine) (If this does not work, try jasmine instead...
Extracting specific columns from a data frame
...r package, if your data.frame is called df1:
library(dplyr)
df1 %>%
select(A, B, E)
This can also be written without the %>% pipe as:
select(df1, A, B, E)
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