LINQPad：如何使用SQLite整数主键自动分配

Question

In SQLite:

If a table contains a column of type INTEGER PRIMARY KEY, then that column becomes an alias for the ROWID.

When a new row is inserted into an SQLite table, the ROWID can either be specified as part of the INSERT statement or it can be assigned automatically by the database engine.

If no ROWID is specified on the insert, or if the specified ROWID has a value of NULL, then an appropriate ROWID is created automatically.

I created a table in SQLite with an integer primary key, and then opened the file in LINQPad. I'm trying to insert a new row into the table via C#:

var episode = new RateableItem()
{
    SourceId = "tal",
    Edition = episodeNum.ToString(),
    Name = episodeName,
    Consumed = false
};

RateableItems.InsertOnSubmit(episode);
SubmitChanges();

In the above example, I haven't specified the pimary key. This fails because LINQPad has mapped the primary key to a non-nullable int, so the generated SQL inserts a 0 into the primary key, which fails because a row with PK 0 already exists.

Is there a way to configure LINQPad with SQLite so that it passes a null for the PK, allowing SQLite to automatically assign the PK value?

Answer 1

Thanks to the sample database that @sgmoore posted in comments, I was able to find that declaring the table primary key as AUTOINCREMENT solves my issue.

CREATE TABLE RateableItem (
  RateableItemId INTEGER PRIMARY KEY AUTOINCREMENT,
  SourceId NVARCHAR(32) NOT NULL,
  Name NVARCHAR(255),
  Edition NVARCHAR(16),
  Consumed BOOLEAN NOT NULL
);

When I added AUTOINCREMENT to my table definition, I was able to create a new object without specifying the key. LINQPad's Schema Explorer doesn't show any difference between a primay key with AUTOINCREMENT versus without, but my script compiles and SQLite assigns a value on SubmitChanges() .

There are some differences in primary key behavior with AUTOINCREMENT. Fortunately these are fine in my scenario.

Answer 2

 var episode = new RateableItem()
 {
     PrimaryKey = null,
     SourceId = "tal",
     Edition = episodeNum.ToString(),
     Name = episodeName,
     Consumed = false
 };

How does that work?