Question : When I want a column to have distinct values, I can either use a constraint create table t1( […]
Tag: constraint
Can’t add Foreign Key Constraint
Question : As far as I can tell it should work, I went through other similar questions but it seemed […]
How to set unique columns combination
Question : see this table: CREATE TABLE IF NOT EXISTS `default_messages_users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `message_id` int(11) NOT […]
CHECK constraint for array column to verify length > 0
Question : I’m playing with postgres table validation rules and trying to set a CHECK constraint for an array column. […]
How to name a constraint which was unnamed during the table creation?
Question : I had created the table by specifying the columns as primary key and not null without giving them […]
Validating the GST Identification Number (GSTIN)
Question : The following image describes the format of the GST Identification Number: The first 2 digits denote the unique […]
Why does MySQL increment the auto_increment value when there’s a constraint violation?
Question : I have a table in a MySQL database with one column id, which has auto_increment and the Primary […]
Mutually exclusive many-to-many relationships
Question : I have a table containers that can have a many-to-many relationships to several tables, let’s say those are […]
Unique Contraint/Index Based On Values
Question : I have a table that has the following column definitions: ID (INT, PK) Name (VarChar) Active (Bit) Bunch_of […]
Postgres: Can I associate index with FK constraint?
Question : Postgres FK constraint and index are independent. Recently I was looked for unused indexes and found trick to […]