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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.
Restrictions on Referential Constraints

Restrictions on Referential Constraints

You must have the REFERENCES privilege to create a referential constraint.

The following restrictions apply to the column that is specified (the referenced column) in the REFERENCES clause:

The referenced and referencing tables must be in the same database.
The referenced column (or set of columns) must have a unique or primary-key constraint.
The referencing and referenced columns must be the same data type.
The only exceptions are that a referencing column must be an integer data type if the referenced column is a serial data type:
- For BIGSERIAL referenced columns, use BIGINT referencing columns.
- For SERIAL referenced columns, use INT referencing columns.
- For SERIAL8 referenced columns, use INT8 referencing columns.
You cannot place a referential constraint on a BYTE or TEXT column.
You cannot place a constraint on any column of a RAW table.
Constraints uses the collation in effect at their time of creation.
A column-level REFERENCES clause can include only a single column name.
Maximum number of columns in a table-level REFERENCES clause is 16.
The total length of the columns in a table-level REFERENCES clause cannot exceed 390 bytes.

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