SQL Language Enhancements

but not:

INSERT INTO t VALUES (1, NULL);

/* fails because all corresponding non-null segments match */

It means that the PRIMARY KEY constraint doesn't allow NULLs whilst the UNIQUE constraint and unique indexes allow an arbitrary number of NULLs. For multi-column result sets of ( SELECT UCL FROM TN ), the common rules for NULLs are applied, i.e. (1, NULL) is distinct from (NULL, 1) and one (NULL, NULL) is distinct from any other (NULL, NULL).

(1.0) DROP GENERATOR

Enables unused generators to be removed from the database. Storage will be freed for re-use upon the next RESTORE. Available in SQL and DSQL.

Syntax Pattern

DROP GENERATOR <generator name>;

From Firebird v.1.0.x

The following were implemented in Firebird 1.0. They are described again here for the convenience of the reader.

(1.0) RECREATE PROCEDURE

This new DDL command lets you create a new stored procedure with the same name as an existing procedure, replacing the old procedure, without needing to drop the old procedure first. The syntax is identical to CREATE PROCEDURE.

Available in SQL and DSQL.

(1.0) RECREATE TABLE

This new DDL command lets you create a new structure for an existing table without needing to drop the old table first. The syntax is identical to CREATE TABLE.

Note

Observe that RECREATE TABLE does not preserve the data in the old table.

Available in SQL and DSQL.

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