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difference between primary key and unique key
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Primary Key:
There can only be one primary key in a table
In some DBMS it cannot be NULL - e.g. MySQL adds NOT NULL
Primary Key is a unique key identifier of the record
Unique Key:
Can be more than one unique key in one table
Unique key can have NULL values
It can be a can...
Rails :include vs. :joins
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.joins will just joins the tables and brings selected fields in return. if you call associations on joins query result, it will fire database queries again
:includes will eager load the included associations and add them in memory. :includes loads all...
How to store a list in a column of a database table
...hrdad's answer to a related question , I get it that a "proper" database table column doesn't store a list. Rather, you should create another table that effectively holds the elements of said list and then link to it directly or through a junction table. However, the type of list I want to creat...
In SQL, how can you “group by” in ranges?
Suppose I have a table with a numeric column (lets call it "score").
15 Answers
15
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How to change MySQL column definition?
I have a mySQL table called test:
3 Answers
3
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resizes wrong; appears to have unremovable `min-width: min-content`
...nge the display property of the fieldset to one of the following values:
table-cell (recommended)
table-column
table-column-group
table-footer-group
table-header-group
table-row
table-row-group
Of these, I recommend table-cell. Both table-row and table-row-group prevent you from changing width, ...
Why is rbindlist “better” than rbind?
I am going through documentation of data.table and also noticed from some of the conversations over here on SO that rbindlist is supposed to be better than rbind .
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PostgreSQL query to list all table names?
Is there any query available to list all tables in my Postgres DB.
7 Answers
7
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Google Docs/Drive - number the headings
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If you want something more easy, there is a Google Add-On called "Table of Contents" that will allow you to number your headings.
To install this add-on:
Click on the Add-Ons > Get Add-Ons.
Click on the "Table of Contents" icon or search for this addon to install it
Then your ...
Best way to strip punctuation from a string
...g.punctuation))
It's performing raw string operations in C with a lookup table - there's not much that will beat that but writing your own C code.
If speed isn't a worry, another option though is:
exclude = set(string.punctuation)
s = ''.join(ch for ch in s if ch not in exclude)
This is faster...