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https://issues.apache.org/jira/browse/CALCITE-3210?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Danny Chan resolved CALCITE-3210.
---------------------------------
Fix Version/s: (was: next)
1.21.0
Resolution: Fixed
Fixed in
[e863294|https://github.com/apache/calcite/commit/e863294ccfbed9dd520c999f75ed0bbe03f9fb1d],
thanks for your PR, [~wangweidong] !
> JDBC adapter should generate "CAST(NULL AS type)" rather than "NULL"
> --------------------------------------------------------------------
>
> Key: CALCITE-3210
> URL: https://issues.apache.org/jira/browse/CALCITE-3210
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.21.0
> Environment: mac os
> Reporter: Wang Weidong
> Assignee: Wang Weidong
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.21.0
>
> Time Spent: 9h 40m
> Remaining Estimate: 0h
>
> I have as sql as follows:
> {code:java}
> select cast(null as varchar) as a{code}
> The process step is :
> # parse sql to SqlNode;
> # convert SqlNode to RelNode;
> # convert RelNode to SqlNode;
> # convert SqlNode to string.
> The result string is:
> {code:java}
> "SELECT NULL AS `A`\n"
> + "FROM (VALUES (0)) AS `t` (`ZERO`)"{code}
> Finally, I found that the result string is absent of cast statement for
> "null" which causes the result sql to be invalid.
> Actually, the result I expect is like:
> {code:java}
> "SELECT CAST(NULL AS VARCHAR) AS `A`\n"
> + "FROM (VALUES (0)) AS `t` (`ZERO`)"{code}
>
> Testing code is as follows
> {code:java}
> // code placeholder
> @Test
> public void testSeletNull() throws SqlParseException {
> String sql = "select cast(null as varchar) as a";
> SqlNode sqlNode = parserContext.parseStmt(sql);
> RelNode relNode =
> parserContext.getSqlToRelConverter().convertQuery(sqlNode, true, true).rel;
> SqlNode sqlNodeNew = toSqlNode(relNode);
> Assert.assertEquals(sqlNodeNew.toString(), "SELECT NULL AS `A`\n"
> + "FROM (VALUES (0)) AS `t` (`ZERO`)");
> }
> private static SqlNode toSqlNode(RelNode root) {
> SqlDialect dialect = MysqlSqlDialect.DEFAULT;
> RelToSqlConverter converter = new RelToSqlConverter(dialect == null ?
> dialect : dialect);
> return converter.visitChild(0, root).asStatement();
> }
> {code}
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