问题
I'm trying to add the NOT_NULL constraint to a column in an SQL h2 database, using
ALTER TABLE CHARACTERS ADD CONSTRAINT nn_PID NOT_NULL (PLAYER_ID);
This follows the pattern I found here:
ALTER TABLE Persons ADD CONSTRAINT pk_PersonID PRIMARY KEY (P_Id,LastName)
Except I change the constraint, table and column names. But I get this error:
Syntax error in SQL statement "ALTER TABLE CHARACTERS ADD CONSTRAINT NN_PID NOT_NULL[*] (PLAYER_ID) "; expected "., COMMENT, PRIMARY, INDEX, KEY, CHECK, UNIQUE, FOREIGN"; SQL statement: ALTER TABLE CHARACTERS ADD CONSTRAINT nn_PID NOT_NULL (PLAYER_ID) [42001-168] 42001/42001 (Help)
How can I add the NOT_NULL constraint?
回答1:
From H2 SQL Grammar:
ALTER TABLE TEST ALTER COLUMN NAME SET NOT NULL;
So we can use:
ALTER TABLE CHARACTERS ALTER PLAYER_ID SET NOT NULL;
来源：https://stackoverflow.com/questions/11672498/adding-the-not-null-constraint-to-an-sql-column