thswlsqls opened a new issue, #39096:
URL: https://github.com/apache/shardingsphere/issues/39096

   ## Bug Report
   
   ### Which version of ShardingSphere did you use?
   master @ 620e40a33c3
   
   ### Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy?
   Both
   
   ### Expected behavior
   `PrestoFunctionOption.getIfNullFunctionName()` should return the 
null-coalescing function that Presto/Trino actually provides, namely `COALESCE`.
   
   ### Actual behavior
   It returns `IFNULL`, a function that does not exist in Presto/Trino. The 
dialect exposes a function name the target database cannot execute.
   
   ### Reason analyze (If you can)
   `PrestoFunctionOption.getIfNullFunctionName()` 
(`database/connector/dialect/presto/src/main/java/org/apache/shardingsphere/database/connector/presto/metadata/database/option/PrestoFunctionOption.java`
 line 35-37) returns the `IFNULL` default inherited from PR #38350. 
Presto/Trino conditional-expression docs list only `COALESCE` for null 
coalescing; there is no `IFNULL`. The sibling 
`PostgreSQLFunctionOption.getIfNullFunctionName()` faces the same absence and 
already returns `COALESCE` (PR #38466), with a committer TODO stating 
IFNULL-less dialects should map onto `COALESCE`. Presto was left uncorrected.
   
   ### Steps to reproduce the behavior, such as: SQL to execute, sharding rule 
configuration, when exception occur etc.
   N/A. The incorrect value is returned directly by the dialect metadata 
capability; see the reason analysis above.
   
   ### Example codes for reproduce this issue (such as a github link).
   N/A
   
   


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