morningman commented on a change in pull request #3135: support subquery in
case when statement
URL: https://github.com/apache/incubator-doris/pull/3135#discussion_r393729725
##########
File path: fe/src/main/java/org/apache/doris/analysis/SelectStmt.java
##########
@@ -1244,6 +1213,46 @@ public void rewriteExprs(ExprRewriter rewriter) throws
AnalysisException {
orderByElem.setExpr(rewriter.rewrite(orderByElem.getExpr(),
analyzer));
}
}
+ if (subqueryInCase) {
+ for (SelectListItem item : selectList.getItems()) {
+ if (!(item.getExpr() instanceof CaseExpr)) {
+ continue;
+ }
+ if
(!item.getExpr().contains(Predicates.instanceOf(Subquery.class))) {
+ continue;
+ }
+ item.setExpr(rewriteSubquery(item.getExpr()));
+ }
+ }
+ }
+
+
+ private Expr rewriteSubquery(Expr expr) throws AnalysisException {
+ if (expr instanceof Subquery) {
+ if (!(((Subquery) expr).getStatement() instanceof SelectStmt) ) {
+ throw new AnalysisException("only support select subquery in
case statement.");
+ }
+ SelectStmt subquery = (SelectStmt)((Subquery) expr).getStatement();
+ if (subquery.getSelectList().getItems().size() != 1) {
+ throw new AnalysisException("only support scala select
subquery in case statement.");
+ }
+ String alias = getTableAliasGenerator().getNextAlias();
+ String colAlias = getColumnAliasGenerator().getNextAlias();
+ InlineViewRef inlineViewRef = new InlineViewRef(alias, subquery,
Arrays.asList(colAlias));
+ try {
+ inlineViewRef.analyze(analyzer);
+ } catch (UserException e) {
+ throw new AnalysisException(e.getMessage());
+ }
+ fromClause_.add(inlineViewRef);
+ expr = new SlotRef(new TableName(null, alias), colAlias);
Review comment:
```suggestion
expr = new SlotRef(new TableName(null, alias), colAlias);
```
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