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How to use count and group by at the same select statement
...atement.
Is there a way for this directly from sql?
For example, having a table with users I want to select the different towns and the total number of users
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Sending a message to nil in Objective-C
...gt; 0 )
or this:
return [myArray count]; // say for number of rows in a table
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The entity type is not part of the model for the current context
...g(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Estate>().ToTable("Estate");
}
If your tables are not created on startup, this is why. You need to tell the DbContext about them in the OnModelCreating method override.
You can either do custom per-entity mappings here, or separate t...
SQLite - replace part of a string
Is it possible using SQL in an SQLite table to replace part of a string?
3 Answers
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Why is std::map implemented as a red-black tree?
...d red black probably only remains for historical reasons.
Why not a hash table?
A type only requires < operator (comparison) to be used as a key in a tree. However, hash tables require that each key type has a hash function defined. Keeping type requirements to a minimum is very important for ...
#1071 - Specified key was too long; max key length is 767 bytes
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767 bytes is the stated prefix limitation for InnoDB tables in MySQL version 5.6 (and prior versions). It's 1,000 bytes long for MyISAM tables. In MySQL version 5.7 and upwards this limit has been increased to 3072 bytes.
You also have to be aware that if you set an index on a...
Which @NotNull Java annotation should I use?
...nt approaches. Some packages use JLS 9.6.4.1 style contexts. The following table gives an overview:
FIELD METHOD PARAMETER LOCAL_VARIABLE
android.support.annotation X X X
edu.umd.cs.findbugs.annotations X X X X
org.jetbra...
How to change a nullable column to not nullable in a Rails migration?
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This causes problems when the table already has null values. See my answer
– Rick Smith
Aug 8 '14 at 20:27
5
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Debugging sqlite database on the device
... debuggable, you can use the shell run-as command to run a command or executable as a specific user/application or just switch to the UID of your application so you can access its data directory.
So if you wish to pull your application database from the device you should run the debug build of the...
Auto margins don't center image in page
...d for margin:auto to center an item in the flow. (display:block or display:table, position:static or position:relative, etc.)
– Phrogz
Apr 20 '11 at 17:26
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