如何通过SQL查询提取SysML值属性的默认初始值？

修改SQL查询关联t_xref表获取初始值 #

SysML值属性的初始（默认）值在EA数据库中通常存储在t_xref表，对应Type为PropertyDefault的条目，Client字段关联值属性的ea_guid。以下是修改后的查询，兼容你当前的筛选逻辑：

SELECT 
    property.ea_guid AS CLASSGUID, 
    property.Object_Type AS CLASSTYPE, 
    property.Name, 
    property.Note as [Notes], 
    classifier.Name AS TYPE,
    -- 针对默认.qeax（Jet数据库）的初始值提取逻辑
    CASE 
        WHEN xref.Description LIKE '%<DefaultValue>%' THEN
            MID(xref.Description, INSTR(xref.Description, '<DefaultValue>') + 15, INSTR(xref.Description, '</DefaultValue>') - INSTR(xref.Description, '<DefaultValue>') - 15)
        ELSE
            xref.Description
    END AS [Default Value]
FROM t_object property   
LEFT JOIN t_object classifier ON property.PDATA1 = classifier.ea_guid   
LEFT JOIN t_object block on property.ParentID = block.Object_ID
-- 关联t_xref筛选初始值条目
LEFT JOIN t_xref xref ON property.ea_guid = xref.Client AND xref.Type = 'PropertyDefault' AND xref.Name = 'DefaultValue'
WHERE block.Object_ID = #OBJECTID# AND property.Object_Type = 'Part' AND classifier.Object_Type = 'DataType'  
ORDER BY property.Name

迁移至Windows数据库（SQL Server）后的适配 #

如果切换到SQL Server，可改用XML解析逻辑提升可靠性：

SELECT 
    property.ea_guid AS CLASSGUID, 
    property.Object_Type AS CLASSTYPE, 
    property.Name, 
    property.Note as [Notes], 
    classifier.Name AS TYPE,
    -- SQL Server下解析XML格式的初始值
    CASE 
        WHEN xref.Description IS NOT NULL THEN
            CAST(xref.Description AS XML).value('(DefaultValue)[1]', 'NVARCHAR(MAX)')
        ELSE
            NULL
    END AS [Default Value]
FROM t_object property   
LEFT JOIN t_object classifier ON property.PDATA1 = classifier.ea_guid   
LEFT JOIN t_object block on property.ParentID = block.Object_ID
LEFT JOIN t_xref xref ON property.ea_guid = xref.Client AND xref.Type = 'PropertyDefault' AND xref.Name = 'DefaultValue'
WHERE block.Object_ID = #OBJECTID# AND property.Object_Type = 'Part' AND classifier.Object_Type = 'DataType'  
ORDER BY property.Name

模板内容选择器优化建议 #

如果之前用模板内容选择器无法筛选值属性，可尝试添加以下匹配条件：

• 匹配ObjectType为Part
• 匹配Classifier.ObjectType为DataType
• 直接使用上述修改后的SQL查询作为内容源，比选择器更灵活可控

内容的提问来源于stack exchange，提问作者Lisa Morgan