I have a table which contains two columns (A and B).column A has default value of 1 or 0. I want to add new column C, its default value is 0 and C'values depends on A'value.
How can I do that using migration in ASP.NET Core.
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2Read the part about computed columns here.user18387401– user183874012022-07-02 11:14:45 +00:00Commented Jul 2, 2022 at 11:14
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"add new column C, its default value is 0 and C'values depends on A'value."Do you mean copy data from one column to another in the same table? If so, see this answerQing Guo– Qing Guo2022-07-05 01:59:18 +00:00Commented Jul 5, 2022 at 1:59
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2 Answers
At first define your columns in a class for example named "Sample", than define a dbSet property in your application context , something like this
public DbSet<Sample> Contacts { get; set; }
If you want to set default value for your columns you can override OnModelCreating method in your application context and set a default value for your columns , like this:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Sample>()
.Propery(p => p.A)
.HasDefaultValue(0);
}
In above code "A" is your intended column name .
Than write Add-Migration in command console to create new migration , than write Update-Database .
Hope it will be useful for you
Comments
try something like this :
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.AddColumn<bool>(
name: "C",
table: "MyTableName",
nullable: false);
migrationBuilder.Sql("UPDATE MyTableName SET C=CASE
WHEN A = 0 THEN 0
WHEN B = 1 THEN 1
...
ELSE 0
END WHERE ...);
}
use whatever condition you need in migrationBuilder
