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I want to specify that either fieldname or freetext must always be present in XML files that apply to this XSD. Is there a way to do that?
<xs:complexType name="tSome">
<xs:sequence>
<!-- either one of the two below has to be present. -->
<xs:element name="fieldname" type="xs:string" />
<xs:element name="freetext" type="xs:string" />
<!-- this one below must always be present -->
<xs:element name="dbtablename" type="xs:string" />
</xs:sequence>
</xs:complexType>
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The "use" property in the XSD definition is used to specify if the attribute is optional or mandatory. To specify that an attribute must be present, use="required" (Note: use may also be set to "prohibited", but we'll come to that later).
The line above: xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" tells the XML parser that this document should be validated against a schema. The line: xsi:noNamespaceSchemaLocation="shiporder. xsd" specifies WHERE the schema resides (here it is in the same folder as "shiporder. xml").
xs:all specifies that the child elements can appear in any order.
A complex element is an XML element that contains other elements and/or attributes.
It can be one of the types included in the XML Schema definition (boolean, string, date, etc.), or it can be a custom type that you can define yourself. You can also add restrictions (facets) to a data type in order to limit its content, or you can require the data to match a specific pattern.
There is a Choice Indicator in XML Schema, which allows you to take one of the contained elements, but not two or more. If you want any 2 of 3, I suggest doing something like this:
<xs:choice>
<xs:element name="fieldname" type="xs:string" minOccurs="0" maxOccurs="1" />
<xs:element name="freetext" type="xs:string" minOccurs="0" maxOccurs="1" />
<xs:element name="dbtablename" type="xs:string" minOccurs="0" maxOccurs="1" />
</xs:choice>
<xs:choice>
<xs:element name="fieldname" type="xs:string" minOccurs="0" maxOccurs="1" />
<xs:element name="freetext" type="xs:string" minOccurs="0" maxOccurs="1" />
<xs:element name="dbtablename" type="xs:string" minOccurs="0" maxOccurs="1" />
</xs:choice>
(Maybe maxOccurs will prevent you from choosing one and the same element twice.)
If that does not work, nothing will I think.
Edited: I didn't correctly understand the question the first time. If you want dbtablename to always be present with any one of fieldname or freetext, then this is the answer:
<xs:complexType name="tSome">
<xs:sequence>
<xs:choice>
<xs:element name="fieldname" type="xs:string" />
<xs:element name="freetext" type="xs:string" />
</xs:choice>
<xs:element name="dbtablename" type="xs:string" />
</xs:sequence>
</xs:complexType>
So, you want either fieldname or freetext and not both? or maybe both? and then dbtablename optionally?
Here is 1 or 2 of the elements:
<xs:choice minOccurs="1" maxOccurs="2">
<xs:element name="fieldname" type="xs:string"/>
<xs:element name="freetext" type="xs:string"/>
<xs:element name="dbtablename" type="xs:string"/>
</xs:choice>
Is this what you want? or did you want dbtablename to be separate?
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