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Create code first, many to many, with additional fields in association table
... not possible to create a many-to-many relationship with a customized join table. In a many-to-many relationship EF manages the join table internally and hidden. It's a table without an Entity class in your model. To work with such a join table with additional properties you will have to create actu...
Is there a typical state machine implementation pattern?
...
I prefer to use a table driven approach for most state machines:
typedef enum { STATE_INITIAL, STATE_FOO, STATE_BAR, NUM_STATES } state_t;
typedef struct instance_data instance_data_t;
typedef state_t state_func_t( instance_data_t *data );
s...
What is a stored procedure?
...ut the user will not need to have read/write permissions on the underlying tables. This is a good first step against SQL injection.
Stored procedures do come with downsides, basically the maintenance associated with your basic CRUD operation. Let's say for each table you have an Insert, Update, Del...
Inserting data into a temporary table
After having created a temporary table and declaring the data types like so;
12 Answers
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Grid of responsive squares
...bove.
With this technique, you can make any other aspect ratio, here is a table giving the values of bottom padding according to the aspect ratio and a 30% width.
Aspect ratio | padding-bottom | for 30% width
------------------------------------------------
1:1 | = width |...
Why use multiple columns as primary keys (composite primary key)
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Another example of compound primary keys are the usage of Association tables. Suppose you have a person table that contains a set of people and a group table that contains a set of groups. Now you want to create a many to many relationship on person and group. Meaning each person can belong t...
Entity Framework Migrations renaming tables and columns
...eign keys with the new column name.
public override void Up()
{
RenameTable("ReportSections", "ReportPages");
RenameTable("ReportSectionGroups", "ReportSections");
RenameColumn("ReportPages", "Group_Id", "Section_Id");
}
public override void Down()
{
RenameColumn("ReportPages", "Se...
A migration to add unique constraint to a combination of columns
...o apply unique constraint to a combination of columns. i.e. for a people table, a combination of first_name , last_Name and Dob should be unique.
...
How can I insert values into a table, using a subquery with more than one result?
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If you are inserting one record into your table, you can do
INSERT INTO yourTable
VALUES(value1, value2)
But since you want to insert more than one record, you can use a SELECT FROM in your SQL statement.
so you will want to do this:
INSERT INTO prices (group,...
Find most frequent value in SQL column
How can I find the most frequent value in a given column in an SQL table?
9 Answers
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