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How do I perform the SQL Join equivalent in MongoDB?
...s bear in mind that MongoDB collections are not equivalent to relational tables; each serves a unique design objective. A normalized table provides an atomic, isolated chunk of data. A document, however, more closely represents an object as a whole. In the case of a social news site, it can be argue...
Best way to select random rows PostgreSQL
...erves nicely.
The query below does not need a sequential scan of the big table, only an index scan.
First, get estimates for the main query:
SELECT count(*) AS ct -- optional
, min(id) AS min_id
, max(id) AS max_id
, max(id) - min(id) AS id_span
FROM big;
The on...
How to create a DataTable in C# and how to add rows?
How do create a DataTable in C#?
13 Answers
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How to drop unique in MySQL?
...you can use the following SQL Script to delete the index in MySQL:
alter table fuinfo drop index email;
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Select count(*) from multiple tables
How can I select count(*) from two different tables (call them tab1 and tab2 ) having as result:
18 Answers
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How to add a WiX custom action that happens only on uninstall (via MSI)?
...ly on uninstalls - not upgrades, not repairs or modifies. According to the table above I had to use
<Custom Action='CA_ID' Before='other_CA_ID'>
(NOT UPGRADINGPRODUCTCODE) AND (REMOVE="ALL")</Custom>
And it worked!
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Convert Rows to columns using 'Pivot' in SQL Server
I have read the stuff on MS pivot tables and I am still having problems getting this correct.
8 Answers
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What is the difference between partitioning and bucketing a table in Hive ?
I know both is performed on a column in the table but how is each operation different.
8 Answers
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How do I import CSV file into a MySQL table?
...alized events-diary CSV from a client that I'm trying to load into a MySQL table so that I can refactor into a sane format. I created a table called 'CSVImport' that has one field for every column of the CSV file. The CSV contains 99 columns , so this was a hard enough task in itself:
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SQLAlchemy: cascade delete
...relationship doesn't dictate the parent-child setup. Using ForeignKey on a table is what sets it up as the child. It doesn't matter if the relationship is on the parent or child.
– d512
Aug 4 '16 at 2:04
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