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Python Pandas merge only certain columns
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This is to merge selected columns from two tables.
If table_1 contains t1_a,t1_b,t1_c..,id,..t1_z columns,
and table_2 contains t2_a, t2_b, t2_c..., id,..t2_z columns,
and only t1_a, id, t2_a are required in the final table, then
mergedCSV = table_1[['t1_a','id']].m...
Why do my list item bullets overlap floating elements
...e CSS below to make the list work alongside the floated content.
display: table; works alongside floated content (filling the gap) but without hiding content behind it. Much like a table does :-)
.img {
float: left;
}
.table {
display: table;
}
<img class="img" src="https://via....
Automatically deleting related rows in Laravel (Eloquent ORM)
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You can actually set this up in your migrations:
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
Source: http://laravel.com/docs/5.1/migrations#foreign-key-constraints
You may also specify the desired action for the "on delete...
Difference between HashSet and HashMap?
... functions. This is critical because HashMap uses power-of two length hash tables." weblogs.java.net/blog/2005/06/18/hashmap-implementation - however, if you look at the doc you'll see that this hash distributes things over "buckets", so in the end I believe two things can get mapped the same bucket...
@UniqueConstraint and @Column(unique = true) in hibernate annotation
...hould have unique values. The same aplies for group.
On the other hand,
@Table(
name = "product_serial_group_mask",
uniqueConstraints = {@UniqueConstraint(columnNames = {"mask", "group"})}
)
Implies that the values of mask + group combined should be unique. That means you can have, for ex...
PostgreSQL Crosstab Query
... create crosstab queries in PostgreSQL?
For example I have the following table:
6 Answers
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Convert Unix timestamp into human readable date using MySQL
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Use FROM_UNIXTIME():
SELECT
FROM_UNIXTIME(timestamp)
FROM
your_table;
See also: MySQL documentation on FROM_UNIXTIME().
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How do I check if a SQL Server text column is empty?
I am using SQL Server 2005. I have a table with a text column and I have many rows in the table where the value of this column is not null, but it is empty. Trying to compare against '' yields this response:
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jQuery document.createElement equivalent?
...is.$OuterDiv = $('<div></div>')
.hide()
.append($('<table></table>')
.attr({ cellSpacing : 0 })
.addClass("text")
)
;
Update: I thought I'd update this post since it still gets quite a bit of traffic. In the comments below there's some discussi...
how do I query sql for a latest record date for each user
I have a table that is a collection entries as to when a user was logged on.
22 Answers
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