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robocop 2010-01-15 05:13:43 +00:00
parent 6105f4a154
commit d74b3f4774
1 changed files with 2 additions and 2 deletions
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4
doc/sql.extensions/README.identity_columns.txt
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@ -21,10 +21,10 @@ Syntax rules:
Notes:
- You cannot alter a identity column to normal column and vice versa.
- Identity columns are implicitly NOT NULL.
- Identity columns doesn't enforce uniqueness automatically. Use UNIQUE or PRIMARY key for that.
- Identity columns don't enforce uniqueness automatically. Use UNIQUE or PRIMARY key for that.
Implementation:
Two columns has been inserted in RDB$RELATION_FIELDS: RDB$GENERATOR_NAME and RDB$IDENTITY_TYPE.
Two columns have been inserted in RDB$RELATION_FIELDS: RDB$GENERATOR_NAME and RDB$IDENTITY_TYPE.
RDB$GENERATOR_NAME stores the automatically created generator for the column. In RDB$GENERATORS,
the value of RDB$SYSTEM_FLAG of that generator will be 6. RDB$IDENTITY_TYPE will currently
always store the value 0 (by default) for identity columns and NULL for non-identity columns.