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Is there a MySQL option/feature to track history of changes to records?
...i AFTER INSERT ON MyDB.data FOR EACH ROW
INSERT INTO MyDB.data_history SELECT 'insert', NULL, NOW(), d.*
FROM MyDB.data AS d WHERE d.primary_key_column = NEW.primary_key_column;
CREATE TRIGGER MyDB.data__au AFTER UPDATE ON MyDB.data FOR EACH ROW
INSERT INTO MyDB.data_history SELECT 'up...
Transaction isolation levels relation with locks on table
... writes data and commit/rollback (depending on results). B just executes a SELECT statement to read data. C reads and updates data. All these process work on the same table T.
READ UNCOMMITTED - no lock on the table. You can read data in the table while writing on it. This means A writes data (unc...
Move entire line up and down in Vim
...;A-down> but when I try those keys in vim in visual running in tmux the selection disappears and the cursor moves line up; without moving the selected lines.
– Konrad
Dec 27 '16 at 9:49
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Rails: How can I set default values in ActiveRecord?
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See Paul Russell's comment on this answer for more details
If you're only selecting a subset of columns for a model (ie; using select in a query like Person.select(:firstname, :lastname).all) you will get a MissingAttributeError if your init method accesses a column that hasn't been included in the...
Does the join order matter in SQL?
...t matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.
For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.
First, outer joins are not commutative, so a LEFT JOIN b is no...
Entity Framework - Include Multiple Levels of Properties
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For EF 6
using System.Data.Entity;
query.Include(x => x.Collection.Select(y => y.Property))
Make sure to add using System.Data.Entity; to get the version of Include that takes in a lambda.
For EF Core
Use the new method ThenInclude
query.Include(x => x.Collection)
.ThenIncl...
How do I use cascade delete with SQL Server?
...elete" to an existing foreign key in SQL Server Management Studio:
First, select your Foreign Key, and open it's "DROP and Create To.." in a new Query window.
Then, just add ON DELETE CASCADE to the ADD CONSTRAINT command:
And hit the "Execute" button to run this query.
By the way, to get a l...
how to edit .csproj file
...these simple steps:
Right click on your project in solution explorer and select Unload Project
Right click on the project (tagged as unavailable in solution explorer) and click "Edit yourproj.csproj". This will open up your CSPROJ file for editing.
After making any changes you want, save and clos...
What is the >>>= operator in C?
...s a boolean it's true, so 0xFULL ? '\0' : -1 evaluates to '\0', which is a character literal whose numerical value is simply 0.
Meanwhile, 0X.1P1 is a hexadecimal floating point literal equal to 2/16 = 0.125. In any case, being non-zero, it's also true as a boolean, so negating it twice with !! ag...
IntelliJ not recognizing a particular file correctly, instead its stuck as a text file
...te the file, I encountered the error 'Unable to parse template "Interface" Selected class file name mapped to not java'. Couldn't find that error message anywhere in Google, so posting it here in case someone else needs it.
– Knetic
Sep 22 '14 at 17:08
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