Home
SQL programmingYou can use the HCL OneDB™ implementation of the SQL language to develop applications for HCL OneDB™ database servers.
Guide to SQL: SyntaxThe HCL OneDB™ Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the HCL OneDB™ dialect of the SQL language.
SQL statementsThis chapter describes the syntax and semantics of SQL statements that are recognized by HCL OneDB™.
ALTER TABLE statementUse the ALTER TABLE statement to modify the schema of an existing table.
ADD Column ClauseUse the ADD Column clause to add a column to a table, and to define constraints on the new column. This clause can also associate a security policy with a table that has no security policy, or can specify a security label for the new column, if the table already has a security policy.
Single-Column Constraint FormatUse the Single-Column Constraint Format to associate one or more constraints with a single column when you alter a table.
Using NOT NULL Constraints with ADD COLUMNIf a table contains data, when you add a column with a NOT NULL constraint you must also include a DEFAULT clause.

Using NOT NULL Constraints with ADD COLUMN

If a table contains data, when you add a column with a NOT NULL constraint you must also include a DEFAULT clause.

If the table is empty, however, you can add a column and apply only the NOT NULL constraint. The following statement is valid whether or not the table contains data:

ALTER TABLE items
   ADD (item_weight DECIMAL(6,2) 
   DEFAULT 2.0 NOT NULL
      BEFORE total_price);