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Access an arbitrary element in a dictionary in Python
..., since dictionaries have no guaranteed order (they're implemented as hash tables). If you want, for example, the value corresponding to the smallest key, thedict[min(thedict)] will do that. If you care about the order in which the keys were inserted, i.e., by "first" you mean "inserted earliest",...
How do SQL EXISTS statements work?
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For 'each' row from Suppliers, check if there 'exists' a row in the Order table that meets the condition Suppliers.supplier_id (this comes from Outer query current 'row') = Orders.supplier_id. When you find the first matching row, stop right there - the WHERE EXISTS has been satisfied.
The magic ...
Get full path of the files in PowerShell
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Get-ChildItem -Recurse *.txt | Format-Table FullName
That is what I used. I feel it is more understandable as it doesn't contain any loop syntax.
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PostgreSQL - how to quickly drop a user with existing privileges
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Doing: CREATE TABLE foo(bar SERIAL); ALTER TABLE foo OWNER TO postgres; CREATE USER testuser; GRANT ALL ON foo TO testuser; DROP USER testuser gave the error messages: ERROR: role "testuser" cannot be dropped because some objects depend...
How do you delete a column by name in data.table?
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Any of the following will remove column foo from the data.table df3:
# Method 1 (and preferred as it takes 0.00s even on a 20GB data.table)
df3[,foo:=NULL]
df3[, c("foo","bar"):=NULL] # remove two columns
myVar = "foo"
df3[, (myVar):=NULL] # lookup myVar contents
# Method 2a ...
Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
...g a little trouble understanding the pass-by-reference properties of data.table . Some operations seem to 'break' the reference, and I'd like to understand exactly what's happening.
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Get Folder Size from Windows Command Line
...Shell I usually look for how you can decompose the high-level goal into suitable lower-level operations.
– Joey
Oct 10 '12 at 8:13
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What is InnoDB and MyISAM in MySQL?
...er on their locking implementation: InnoDB locks the particular row in the table, and MyISAM locks the entire MySQL table.
You can specify the type by giving MYISAM OR InnoDB while creating a table in DB.
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avoid page break inside row of table
I want to avoid page break inside row of table in html, when I convert html to PDF by wkhtmltopdf. I use page-break-inside:avoid with table- its works, but I have so many rows,
then not work.
If set display of tr as block or some thing else then it change the formatting of table and insert double...
How can I tell when a MySQL table was last updated?
...updated the xx/xx/200x" with this date being the last time a certain mySQL table has been updated.
15 Answers
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