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How do I create a foreign key in SQL Server?
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create table question_bank
(
question_id uniqueidentifier primary key,
question_exam_id uniqueidentifier not null,
question_text varchar(1024) not null,
question_point_value decimal,
constraint fk_questionbank_ex...
MySQL select 10 random rows from 600K rows fast
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SELECT column FROM table
ORDER BY RAND()
LIMIT 10
Not the efficient solution but works
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How can foreign key constraints be temporarily disabled using T-SQL?
... database just run this code:
-- disable all constraints
EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"
To switch them back on, run: (the print is optional of course and it is just listing the tables)
-- enable all constraints
exec sp_MSforeachtable @command1="print '?'", @command...
How to 'insert if not exists' in MySQL?
I started by googling, and found this article which talks about mutex tables.
10 Answers
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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
Let's say I have the following data.table in R :
3 Answers
3
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Rails migration for change column
We have script/generate migration add_fieldname_to_tablename fieldname:datatype syntax for adding new columns to a model.
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Best practices for SQL varchar column length [closed]
Every time is set up a new SQL table or add a new varchar column to an existing table, I am wondering one thing: what is the best value for the length .
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How to make a JTable non-editable
How to make a JTable non-editable? I don't want my users to be able to edit the values in cells by double-clicking them.
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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 ...
How to see the values of a table variable at debug time in T-SQL?
Can we see the values (rows and cells) in a table valued variable in SQL Server Management Studio (SSMS) during debug time? If yes, how?
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