Merge pull request #909 from katzyn/derived_column_list

Derived column list

h2/src/docsrc/help/help.csv

@@ -2256,7 +2256,8 @@ ID + 20
 "
 
 "Other Grammar","Table Expression","
-{ [ schemaName. ] tableName | ( select ) | valuesExpression } [ [ AS ] newTableAlias ]
+{ [ schemaName. ] tableName | ( select ) | valuesExpression }
+[ [ AS ] newTableAlias [ ( columnName [,...] ) ] ]
 [ USE INDEX ([ indexName [,...] ]) ]
 [ { { LEFT | RIGHT } [ OUTER ] | [ INNER ] | CROSS | NATURAL }
     JOIN tableExpression [ ON expression ] ]

h2/src/main/org/h2/command/Parser.java

@@ -1374,6 +1374,10 @@ public class Parser {
                 alias = readFromAlias(null);
                 if (alias != null) {
                     top.setAlias(alias);
+                    ArrayList<String> derivedColumnNames = readDerivedColumnNames();
+                    if (derivedColumnNames != null) {
+                        top.setDerivedColumns(derivedColumnNames);
+                    }
                 }
                 return top;
             }
@@ -1426,6 +1430,7 @@ public class Parser {
                 table = readTableOrView(tableName);
             }
         }
+        ArrayList<String> derivedColumnNames = null;
         IndexHints indexHints = null;
         // for backward compatibility, handle case where USE is a table alias
         if (readIf("USE")) {
@@ -1433,10 +1438,12 @@ public class Parser {
                 indexHints = parseIndexHints(table);
             } else {
                 alias = "USE";
+                derivedColumnNames = readDerivedColumnNames();
             }
         } else {
             alias = readFromAlias(alias);
             if (alias != null) {
+                derivedColumnNames = readDerivedColumnNames();
                 // if alias present, a second chance to parse index hints
                 if (readIf("USE")) {
                     read("INDEX");
@@ -1448,8 +1455,12 @@ public class Parser {
         if (table.isView() && table.isTableExpression() && alias == null) {
             alias = table.getName();
         }
-        return new TableFilter(session, table, alias, rightsChecked,
+        TableFilter filter = new TableFilter(session, table, alias, rightsChecked,
                 currentSelect, orderInFrom++, indexHints);
+        if (derivedColumnNames != null) {
+            filter.setDerivedColumns(derivedColumnNames);
+        }
+        return filter;
     }
 
     private IndexHints parseIndexHints(Table table) {
@@ -1485,6 +1496,18 @@ public class Parser {
         return readFromAlias(alias, excludeIdentifiers);
     }
 
+    private ArrayList<String> readDerivedColumnNames() {
+        if (readIf("(")) {
+            ArrayList<String> derivedColumnNames = New.arrayList();
+            do {
+                derivedColumnNames.add(readAliasIdentifier());
+            } while (readIf(","));
+            read(")");
+            return derivedColumnNames;
+        }
+        return null;
+    }
+
     private Prepared parseTruncate() {
         read("TABLE");
         Table table = readTableOrView();

h2/src/main/org/h2/command/dml/Select.java

@@ -737,8 +737,9 @@ public class Select extends Query {
             if (filter.isNaturalJoinColumn(c)) {
                 continue;
             }
+            String name = filter.getDerivedColumnName(c);
             ExpressionColumn ec = new ExpressionColumn(
-                    session.getDatabase(), null, alias, c.getName());
+                    session.getDatabase(), null, alias, name != null ? name : c.getName());
             expressions.add(index++, ec);
         }
         return index;

h2/src/main/org/h2/command/dml/SelectListColumnResolver.java

@@ -52,6 +52,11 @@ public class SelectListColumnResolver implements ColumnResolver {
         return columns;
     }
 
+    @Override
+    public String getDerivedColumnName(Column column) {
+        return null;
+    }
+
     @Override
     public String getSchemaName() {
         return null;

h2/src/main/org/h2/expression/ExpressionColumn.java

@@ -33,7 +33,7 @@ public class ExpressionColumn extends Expression {
     private final Database database;
     private final String schemaName;
     private final String tableAlias;
-    private final String columnName;
+    private String columnName;
     private ColumnResolver columnResolver;
     private int queryLevel;
     private Column column;
@@ -89,7 +89,10 @@ public class ExpressionColumn extends Expression {
             return;
         }
         for (Column col : resolver.getColumns()) {
-            String n = col.getName();
+            String n = resolver.getDerivedColumnName(col);
+            if (n == null) {
+                n = col.getName();
+            }
             if (database.equalsIdentifiers(columnName, n)) {
                 mapColumn(resolver, col, level);
                 return;
@@ -253,6 +256,12 @@ public class ExpressionColumn extends Expression {
     @Override
     public String getAlias() {
         if (column != null) {
+            if (columnResolver != null) {
+                String name = columnResolver.getDerivedColumnName(column);
+                if (name != null) {
+                    return name;
+                }
+            }
             return column.getName();
         }
         if (tableAlias != null) {

h2/src/main/org/h2/table/ColumnResolver.java

@@ -30,6 +30,14 @@ public interface ColumnResolver {
      */
     Column[] getColumns();
 
+    /**
+     * Get derived column name, or {@code null}.
+     *
+     * @param column column
+     * @return derived column name, or {@code null}
+     */
+    String getDerivedColumnName(Column column);
+
     /**
      * Get the list of system columns, if any.
      *

h2/src/main/org/h2/table/SingleColumnResolver.java

@@ -42,6 +42,11 @@ public class SingleColumnResolver implements ColumnResolver {
         return new Column[] { column };
     }
 
+    @Override
+    public String getDerivedColumnName(Column column) {
+        return null;
+    }
+
     @Override
     public String getSchemaName() {
         return null;

h2/src/main/org/h2/table/TableBase.java

@@ -39,7 +39,7 @@ public abstract class TableBase extends Table {
         if (data.tableEngineParams != null) {
             this.tableEngineParams = data.tableEngineParams;
         } else {
-            this.tableEngineParams = Collections.EMPTY_LIST;
+            this.tableEngineParams = Collections.emptyList();
         }
         setTemporary(data.temporary);
         Column[] cols = data.columns.toArray(new Column[0]);

h2/src/main/org/h2/table/TableFilter.java

@@ -6,6 +6,7 @@
 package org.h2.table;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.HashSet;
 import org.h2.api.ErrorCode;
 import org.h2.command.Parser;
@@ -117,6 +118,8 @@ public class TableFilter implements ColumnResolver {
     private final int hashCode;
     private final int orderInFrom;
 
+    private HashMap<Column, String> derivedColumnMap;
+
     /**
      * Create a new table filter object.
      *
@@ -992,6 +995,12 @@ public class TableFilter implements ColumnResolver {
         return table.getColumns();
     }
 
+    @Override
+    public String getDerivedColumnName(Column column) {
+        HashMap<Column, String> map = derivedColumnMap;
+        return map != null ? map.get(column) : null;
+    }
+
     /**
      * Get the system columns that this table understands. This is used for
      * compatibility with other databases. The columns are only returned if the
@@ -1056,6 +1065,30 @@ public class TableFilter implements ColumnResolver {
         this.alias = alias;
     }
 
+    /**
+     * Set derived column list.
+     *
+     * @param derivedColumnNames names of derived columns
+     */
+    public void setDerivedColumns(ArrayList<String> derivedColumnNames) {
+        Column[] columns = getColumns();
+        int count = columns.length;
+        if (count != derivedColumnNames.size()) {
+            throw DbException.get(ErrorCode.COLUMN_COUNT_DOES_NOT_MATCH);
+        }
+        HashMap<Column, String> map = new HashMap<>(count);
+        for (int i = 0; i < count; i++) {
+            String alias = derivedColumnNames.get(i);
+            for (int j = 0; j < i; j++) {
+                if (alias.equals(derivedColumnNames.get(j))) {
+                    throw DbException.get(ErrorCode.DUPLICATE_COLUMN_NAME_1, alias);
+                }
+            }
+            map.put(columns[i], alias);
+        }
+        this.derivedColumnMap = map;
+    }
+
     @Override
     public Expression optimize(ExpressionColumn expressionColumn, Column column) {
         return expressionColumn;

h2/src/test/org/h2/test/db/TestIndex.java

@@ -712,7 +712,7 @@ public class TestIndex extends TestBase {
 
     public static ResultSet testFunctionIndexFunction() {
         // There are additional callers like JdbcConnection.prepareCommand() and
-        // CommandContainer.recompileIfReqired()
+        // CommandContainer.recompileIfRequired()
         for (StackTraceElement element : Thread.currentThread().getStackTrace()) {
             if (element.getClassName().startsWith(Select.class.getName())) {
                 testFunctionIndexCounter++;

h2/src/test/org/h2/test/scripts/TestScript.java

@@ -82,6 +82,7 @@ public class TestScript extends TestBase {
         reconnectOften = !config.memory && config.big;
 
         testScript("testScript.sql");
+        testScript("derived-column-names.sql");
         testScript("joins.sql");
         testScript("altertable-index-reuse.sql");
         testScript("query-optimisations.sql");

h2/src/test/org/h2/test/scripts/derived-column-names.sql

+-- Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
+-- and the EPL 1.0 (http://h2database.com/html/license.html).
+-- Initial Developer: H2 Group
+--
+
+SELECT * FROM (VALUES(1, 2));
+> C1 C2
+> -- --
+> 1  2
+> rows: 1
+
+SELECT * FROM (VALUES(1, 2)) AS T;
+> C1 C2
+> -- --
+> 1  2
+> rows: 1
+
+SELECT * FROM (VALUES(1, 2)) AS T(A, B);
+> A B
+> - -
+> 1 2
+> rows: 1
+
+SELECT A AS A1, B AS B1 FROM (VALUES(1, 2)) AS T(A, B);
+> A1 B1
+> -- --
+> 1  2
+> rows: 1
+
+SELECT A AS A1, B AS B1 FROM (VALUES(1, 2)) AS T(A, B) WHERE A <> B;
+> A1 B1
+> -- --
+> 1  2
+> rows: 1
+
+SELECT A AS A1, B AS B1 FROM (VALUES(1, 2)) AS T(A, B) WHERE A1 <> B1;
+> exception
+
+SELECT * FROM (VALUES(1, 2)) AS T(A);
+> exception
+
+SELECT * FROM (VALUES(1, 2)) AS T(A, a);
+> exception
+
+SELECT * FROM (VALUES(1, 2)) AS T(A, B, C);
+> exception
+
+SELECT V AS V1, A AS A1, B AS B1 FROM (VALUES (1)) T1(V) INNER JOIN (VALUES(1, 2)) T2(A, B) ON V = A;
+> V1 A1 B1
+> -- -- --
+> 1  1  2
+> rows: 1
+
+CREATE TABLE TEST(I INT, J INT);
+> ok
+
+CREATE INDEX TEST_I_IDX ON TEST(I);
+> ok
+
+INSERT INTO TEST VALUES (1, 2);
+> update count: 1
+
+SELECT * FROM (TEST) AS T(A, B);
+> A B
+> - -
+> 1 2
+> rows: 1
+
+SELECT * FROM TEST AS T(A, B);
+> A B
+> - -
+> 1 2
+> rows: 1
+
+SELECT * FROM TEST AS T(A, B) USE INDEX (TEST_I_IDX);
+> A B
+> - -
+> 1 2
+> rows: 1
+
+DROP TABLE TEST;
+> ok

h2/src/tools/org/h2/build/doc/dictionary.txt

@@ -765,4 +765,4 @@ jacoco xdata invokes sourcefiles classfiles duplication crypto stacktraces prt d
 interpolated thead
 
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-london dfs weekdays intermittent looked msec tstz africa monrovia asia tokyo weekday
+london dfs weekdays intermittent looked msec tstz africa monrovia asia tokyo weekday joi callers