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Diffstat (limited to 'doc')
-rw-r--r-- | doc/manual.xhtml | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/doc/manual.xhtml b/doc/manual.xhtml index 6257cf7..e14f2cf 100644 --- a/doc/manual.xhtml +++ b/doc/manual.xhtml @@ -13261,10 +13261,13 @@ SHOW integer_datetimes <p>In Oracle empty <code>VARCHAR2</code> and <code>NVARCHAR2</code> strings are represented as <code>NULL</code> values. As a result, - in the generated schema, columns of these types are always - declared as <code>NULL</code>, even if explicitly declared as + in the generated schema, columns of these types are declared as + <code>NULL</code> even if explicitly declared as <code>NOT NULL</code> with the <code>db not_null</code> pragma - (<a href="#12.4.5">Section 12.4.5, "<code>null/not_null</code>"</a>).</p> + (<a href="#12.4.5">Section 12.4.5, "<code>null/not_null</code>"</a>), + except for primary key columns. This also means that for object ids + that are mapped to these Oracle types, an empty string is an invalid + value.</p> <p>The Oracle ODB runtime library also provides support for mapping the <code>std::string</code> type to the Oracle <code>CHAR</code>, |