[empire-db] branch master updated: EMPIREDB-398 DBCommand: omit parent tables in FROM clause

[doebele]

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doebele pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/empire-db.git


The following commit(s) were added to refs/heads/master by this push:
     new d42b3433 EMPIREDB-398 DBCommand: omit parent tables in FROM clause
d42b3433 is described below

commit d42b3433f772594e7b52d59b715525880936bb3a
Author: Rainer Döbele <doeb...@apache.org>
AuthorDate: Mon Dec 12 14:07:30 2022 +0100

    EMPIREDB-398 DBCommand: omit parent tables in FROM clause
---
 .../main/java/org/apache/empire/db/DBCommand.java  | 25 +++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/empire-db/src/main/java/org/apache/empire/db/DBCommand.java 
b/empire-db/src/main/java/org/apache/empire/db/DBCommand.java
index 147566b1..7e23997b 100644
--- a/empire-db/src/main/java/org/apache/empire/db/DBCommand.java
+++ b/empire-db/src/main/java/org/apache/empire/db/DBCommand.java
@@ -78,6 +78,8 @@ public abstract class DBCommand extends DBCommandExpr
     protected List<DBCompareExpr>  where           = null;
     protected List<DBCompareExpr>  having          = null;
     protected List<DBColumnExpr>   groupBy         = null;
+    
+    protected Set<DBRowSet>        parentTables    = null; // omit parent 
tables in subqueries
 
     // Parameters for prepared Statements generation
     protected boolean              autoPrepareStmt = false;
@@ -257,6 +259,22 @@ public abstract class DBCommand extends DBCommandExpr
                removeCommandParams(cmp);
         }
     }
+    
+    /**
+     * Set parent tables for subquery command generation.
+     * Parent tables will be omitted to the FROM clause.
+     * @param rowSets
+     */
+    public void setParentTables(DBRowSet... rowSets)
+    {
+        if (rowSets.length>0)
+        {   // add all rowsets
+            this.parentTables = new HashSet<DBRowSet>(rowSets.length);
+            for (DBRowSet r : rowSets)
+                this.parentTables.add(r);
+        }
+        else this.parentTables = null;
+    }
 
     /**
      * Returns true if the this command has either Select or Set expressions
@@ -1352,6 +1370,7 @@ public abstract class DBCommand extends DBCommandExpr
     public void clear()
     {
         cmdParams.clear(0);
+        parentTables = null;
         clearSelectDistinct();
         clearSelect();
         clearSet();
@@ -1821,8 +1840,12 @@ public abstract class DBCommand extends DBCommandExpr
         }
         for (int i=0; i<tables.size(); i++)
         {
+            DBRowSet t = tables.get(i);
+            // check whether it's a parent table
+            if (this.parentTables!=null && this.parentTables.contains(t))
+                continue; // yes, ignore
+            // append
             if (sep) sql.append(", ");
-            DBRowSet t = tables.get(i); 
             t.addSQL(sql, CTX_DEFAULT|CTX_ALIAS);
             sep = true;
         }