Database Program Translation - Information Systems Reengineering, Integration and Normalization - page 218

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Case Study of Translating an SQL Query into XPath Query
Case studies of queries for security trading client statement are used to illustrate
query translation between XPath and SQL.
Table record sequence number column
For any table to be used for query translation, an extra column— seqno is
required. These columns are used by the XML gateway and therefore the following
paragraphs first explain the usage and maintenance of these columns.
For each table, the last column is seqno . This seqno columns are used to ensure
the records returned from database is in right order and this column is used for
translation XQL location index functions (e.g., position()).