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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.
Default Column for the References Clause

Default Column for the References Clause

If the referenced table is different from the referencing table, you do not need to specify the referenced column; the default column is the primary-key column (or columns) of the referenced table. If the referenced table is the same as the referencing table, you must specify the referenced column.

The following example creates a new column in the cust_calls table, ref_order. The ref_order column is a foreign key that references the order_num column in the orders table.

ALTER TABLE cust_calls 
   ADD ref_order INTEGER 
   REFERENCES orders (order_num) 
   BEFORE user_id;

When you place a referential constraint on a column or set of columns, and a duplicate or unique index already exists on that column or set of columns, the index is shared.