tristaZero commented on issue #4852: Add start-index and stop-index assertion for OrderByItem URL: https://github.com/apache/incubator-shardingsphere/issues/4852#issuecomment-601115961 This issue is to count the `start-index` and `stop-index` to assert `IndexOrderByItem ` and `ExpressionOrderByItem` ### How to find the targets to be fixed? 1. Open class `OrderByItemAssert` and clear the comment of `SQLSegmentAssert.assertIs(assertContext, actual, expected)` in `assertIndexOrderByItem` and `assertExpressionOrderByItem`. 2. run `SQLParserParameterizedTest` 3. All the SQL cases which have the error assertion results are our targets to be fixed. ### How to fix the above assertion results? 1. Look at the exception log and find the corresponding `SQL Case ID` and `SQL`. 2. Find out the `parsing result` of this `SQL Case ID` in `./incubator-shardingsphere/shardingsphere-sql-parser/shardingsphere-sql-parser-test/src/test/resources/sql/dml` 3. Calculate the correct `start-index` and `stop-index` of `index-item` and `expression-item` segments of this `SQL`. 4. Add the calculated `start-index` and `stop-index` labels of `index-item` and `expression-item` segments to `parsing result` of this `SQL Case ID`, like ``` <index-item index="2" order-direction="DESC" start-index="10" stop-index="11" /> ``` 5. Add the correct `literal-start-index` and `literal-stop-index` of `index-item` and `expression-item` segments to `parsing result` of this `SQL Case ID` when it is necessary, like ``` <index-item index="2" order-direction="DESC" literal-start-index="10" literal-stop-index="11" /> ``` 6. Run `SQLParserParameterizedTest` again to check whether this `SQL Case ID` does not stay in the list of `SQL` with `bad assertion result`. ### Note 1. What are the definitions of `index-item` and `expression-item` segments? For instance, here is a SQL, > SELECT user_id, SUM(order_id) AS orders_sum FROM t_order GROUP BY user_id ORDER BY SUM(order_id) LIMIT 5 The value of `SUM(order_id)` is a `expression-item`, which always locates behind `order by` or `group by` clause. > SELECT user_id, SUM(order_id) AS orders_sum FROM t_order ORDER BY 1 The value of `1` is `index-item`, which means item index used for `order by` or `group by`. 2. What is the difference between `literal-start-index` and `start-index`? When a SQL does not contain parameter maker, i.e.,`?`, this SQL only has one form; Otherwise, you will see two forms of this SQL, i.e, a SQL form filled with parameter and a SQL form only with parameter marks. For instance, ``` Case1 One SQL without parameter mark, select * from table where id = 1; Case2 One SQL with parameter mark, Original SQL: select * from table where id = ?; SQL filled with Parameter: select * from table where id = 1; ``` Replace `the parameter mark` with `the actual parameter` will change the position of the segment. Therefore we need to add `start-index` to represent the start position of a segment for `Original SQL`, and `literal-start-index` is used to represent the start position of a segment for `SQL filled with Parameter`.
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