![]() Foreign Key: A field or group of fields in a record that must match a key in another table.In most cases, you can leave this to the default value. Other options are NOCASE, which is case-insensitive, and RTRIM, which ignores trailing white space. Collation: Sqlite can use different methods of string comparison.For example, you might check that the value in a phone number field has at least 10 characters. Check: A field can have a check performed on it when a record is added.Default: A default value will be provided if a record is added that has no value in this field.U (Unique): This field in each record must hold a unique value, meaning there can't be any duplicates in this field in the table.We used this in the "id" field in the example we covered above. AI (Auto-Incrementing): Numeric fields can be automatically filled in, with the next highest unused value.There can only be one primary key in a table. In a table of user accounts, though, it might be a username. This might be a simple numeric value, like the auto-incrementing integer fields we covered above. PK (Primary Key): A field (or group of fields) that provides a unique identifier for the records in the table.If you try to add a record without providing a value for this field, it will be rejected. NN (Not Null): When this option is set, the field can't be left empty.You can make sure the command does what you think it's going to before you hard-code some SQL into your application. Browse and search for database records.Create, edit, and delete tables and indexes. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |