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+<!-- keywords: sqlite3_vtab_rhs_value -->
+<div class=nosearch>
+<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
+<h2>Constraint values in xBestIndex()</h2>
+</div>
+<blockquote><pre>
+int sqlite3_vtab_rhs_value(sqlite3_index_info*, int, sqlite3_value **ppVal);
+</pre></blockquote>
+<p>
+This API may only be used from within the <a href="../vtab.html#xbestindex">xBestIndex method</a>
+of a <a href="../vtab.html">virtual table</a> implementation. The result of calling this interface
+from outside of an xBestIndex method are undefined and probably harmful.</p>
+
+<p>When the sqlite3_vtab_rhs_value(P,J,V) interface is invoked from within
+the <a href="../vtab.html#xbestindex">xBestIndex</a> method of a <a href="../vtab.html">virtual table</a> implementation, with P being
+a copy of the <a href="../c3ref/index_info.html">sqlite3_index_info</a> object pointer passed into xBestIndex and
+J being a 0-based index into P->aConstraint[], then this routine
+attempts to set *V to the value of the right-hand operand of
+that constraint if the right-hand operand is known. If the
+right-hand operand is not known, then *V is set to a NULL pointer.
+The sqlite3_vtab_rhs_value(P,J,V) interface returns SQLITE_OK if
+and only if *V is set to a value. The sqlite3_vtab_rhs_value(P,J,V)
+inteface returns SQLITE_NOTFOUND if the right-hand side of the J-th
+constraint is not available. The sqlite3_vtab_rhs_value() interface
+can return an result code other than SQLITE_OK or SQLITE_NOTFOUND if
+something goes wrong.</p>
+
+<p>The sqlite3_vtab_rhs_value() interface is usually only successful if
+the right-hand operand of a constraint is a literal value in the original
+SQL statement. If the right-hand operand is an expression or a reference
+to some other column or a <a href="../c3ref/bind_blob.html">host parameter</a>, then sqlite3_vtab_rhs_value()
+will probably return <a href="../rescode.html#notfound">SQLITE_NOTFOUND</a>.</p>
+
+<p>Some constraints, such as <a href="../c3ref/c_index_constraint_eq.html">SQLITE_INDEX_CONSTRAINT_ISNULL</a> and
+<a href="../c3ref/c_index_constraint_eq.html">SQLITE_INDEX_CONSTRAINT_ISNOTNULL</a>, have no right-hand operand. For such
+constraints, sqlite3_vtab_rhs_value() always returns SQLITE_NOTFOUND.</p>
+
+<p>The <a href="../c3ref/value.html">sqlite3_value</a> object returned in *V is a protected sqlite3_value
+and remains valid for the duration of the xBestIndex method call.
+When xBestIndex returns, the sqlite3_value object returned by
+sqlite3_vtab_rhs_value() is automatically deallocated.</p>
+
+<p>The "_rhs_" in the name of this routine is an abbreviation for
+"Right-Hand Side".
+</p><p>See also lists of
+ <a href="../c3ref/objlist.html">Objects</a>,
+ <a href="../c3ref/constlist.html">Constants</a>, and
+ <a href="../c3ref/funclist.html">Functions</a>.</p>
+