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Convert Datetime column from UTC to local time in select statement
I'm doing a few SQL select queries and would like to convert my UTC datetime column into local time to be displayed as local time in my query results. Note, I am NOT looking to do this conversion via code but rather when I am doing manual and random SQL queries against my databases.
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Duplicating a MySQL table, indices, and data
...ese 2 queries:
CREATE TABLE newtable LIKE oldtable;
INSERT INTO newtable SELECT * FROM oldtable;
To copy just structure and data use this one:
CREATE TABLE tbl_new AS SELECT * FROM tbl_old;
I've asked this before:
Copy a MySQL table including indexes
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Cast int to varchar
...datatype, there is no varchar datatype that you can cast/convert data to:
select CAST(id as CHAR(50)) as col1
from t9;
select CONVERT(id, CHAR(50)) as colI1
from t9;
See the following SQL — in action — over at SQL Fiddle:
/*! Build Schema */
create table t9 (id INT, name VARCHAR(55));
ins...
Postgres manually alter sequence
...
The parentheses are misplaced:
SELECT setval('payments_id_seq', 21, true); # next value will be 22
Otherwise you're calling setval with a single argument, while it requires two or three.
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Javascript Equivalent to C# LINQ Select
...always add custom methods to the array prototype as well:
Array.prototype.select = function(expr){
var arr = this;
//do custom stuff
return arr.map(expr); //or $.map(expr);
};
var ids = this.fruits.select(function(v){
return v.Id;
});
An extended version that uses the function ...
How do I wrap a selection with an HTML tag in Visual Studio?
...Studio 2015 comes with a new shortcut, Shift+Alt+W, that wraps the current selection with a div. This shortcut leaves the text "div" selected, making it seamlessly changeable to any desired tag. This coupled with the automatic end tag replacement makes for a quick solution.
UPDATE
This shortcut is a...
postgresql list and order tables by size
...
select table_name, pg_relation_size(quote_ident(table_name))
from information_schema.tables
where table_schema = 'public'
order by 2
This shows you the size of all tables in the schema public if you have multiple schemas, y...
what is the difference between GROUP BY and ORDER BY in sql
... SUM, COUNT, AVG, etc).
TABLE:
ID NAME
1 Peter
2 John
3 Greg
4 Peter
SELECT *
FROM TABLE
ORDER BY NAME
=
3 Greg
2 John
1 Peter
4 Peter
SELECT Count(ID), NAME
FROM TABLE
GROUP BY NAME
=
1 Greg
1 John
2 Peter
SELECT NAME
FROM TABLE
GROUP BY NAME
HAVING Count(ID) > 1
=
Peter
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How important is the order of columns in indexes?
I've heard that you should put columns that will be the most selective at the beginning of the index declaration. Example:
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Count table rows
...
SELECT COUNT(*) FROM fooTable;
will count the number of rows in the table.
See the reference manual.
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