SQLite：插入到身份列

Question

I'm new to SQLite and I'm trying to run the following code:

using (var cn = new SQLiteConnection("Data Source=:memory:;Version=3;")) {
    cn.Open();

    var cmd = cn.CreateCommand();
    cmd.CommandText = "CREATE TABLE [ContentItems] ([Id] [int] IDENTITY(1,1) NOT NULL, [Title] [nvarchar](100) NOT NULL, CONSTRAINT [PK_ContentItems] PRIMARY KEY ([Id]))";
    cmd.ExecuteNonQuery();

    var cmd2 = cn.CreateCommand();
    cmd2.CommandText = "INSERT INTO [ContentItems] (Title) VALUES ('Test 1')";
    cmd2.ExecuteNonQuery();
}

But this gives the error:

Abort due to constraint violation ContentItems.Id may not be NULL

I've had a look through the documentation but based on my past SQL experience i cannot see why this doesn't work. I'd appreciate the help. Thanks

Answer 1

SQLite creates what you're thinking of as an IDENTITY column using the AUTOINCREMENT keyword. In your example, the ID column is not created with AUTOINCREMENT and, since it is declared NOT NULL, you must supply a value.

The CREATE statement you're after is:

 CREATE TABLE [ContentItems] (
    [Id] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, 
    [Title] TEXT NOT NULL, 
    CONSTRAINT [PK_ContentItems] PRIMARY KEY ([Id])
 )

Note that SQLite uses the TEXT data type (although it will map anything containing "CHAR" to that datatype) and doesn't need or respect maximum field lengths.