Question

Say I defined a char column Type. I want to strict its value to say for example (Black, White, Red, Blue) Only…

How can I do that??

All i know, this is easy in Access 😛

Answer 1

If there are just a few permitted values then you can use a CHECK constraint:

ALTER TABLE dbo.Your_Table ADD CONSTRAINT CK_YourTable_YourColumn     CHECK (Your_Column IN ('Black', 'White', 'Red', 'Blue')) 

If there are more values then you can use a lookup table and a FOREIGN KEY constraint:

CREATE TABLE dbo.Lookup_Colours (Colour VARCHAR(10)) -- then populate Lookup_Colours with all permitted values  ALTER TABLE dbo.Your_Table ADD CONSTRAINT FK_YourTable_YourColumn     FOREIGN KEY (Your_Column)     REFERENCES dbo.Lookup_Colours (Colour)