| 摘要 |
A method and apparatus accepts a query to update or delete rows in a temporal table of a database. The query may describe which rows are to be updated, a calculation for the value to be used to update each row of the table, and a period of validity, during which the changes are to take place. The method and apparatus creates a sequence of queries and SQL program elements that together can make up an SQL program that will execute the query received. The SQL program can split any row of the table to be updated into multiple rows so that each of the multiple rows of the table to be changed have an effective period during which no changes occur in the table to be changed or any other tables referenced in the query received and no effective periods span the beginning or the end of the period of validity. The specified change may then be made to the resulting rows, and rows that are adjacent in time with identical values may be collapsed into a single row. The result is inserted into the table to be changed and the corresponding original rows in the table to be changed are deleted. The method and apparatus operates for queries received to update or delete a table.
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