| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * GroupResult.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | */ |
| 33 | package smallsql.database; |
| 34 | |
| 35 | import java.sql.*; |
| 36 | |
| 37 | /** |
| 38 | * @author Volker Berlin |
| 39 | * |
| 40 | */ |
| 41 | class GroupResult extends MemoryResult{ |
| 42 | |
| 43 | private Expression currentGroup; //Validate if the current row of cmd is part of the current group |
| 44 | private RowSource from; |
| 45 | private Expressions groupBy; // the list of Expressions in the GROUP BY clause |
| 46 | private Expressions expressions = new Expressions(); // List of Expression |
| 47 | private Expressions internalExpressions = new Expressions(); // a list of Aggregate Function and ColNames from SELECT, GROUP BY and HAVING |
| 48 | |
| 49 | /** |
| 50 | * Constructor for Grouping a Result from a CommandSelect |
| 51 | */ |
| 52 | GroupResult(CommandSelect cmd, RowSource from, Expressions groupBy, Expression having, Expressions orderBy) throws SQLException{ |
| 53 | this.from = from; |
| 54 | this.groupBy = groupBy; |
| 55 | |
| 56 | if(groupBy != null){ |
| 57 | for(int i=0; i<groupBy.size(); i++){ |
| 58 | Expression left = groupBy.get(i); |
| 59 | int idx = addInternalExpressionFromGroupBy( left ); |
| 60 | ExpressionName right = new ExpressionName(null); |
| 61 | right.setFrom(this, idx, new ColumnExpression(left)); |
| 62 | Expression expr = new ExpressionArithmetic( left, right, ExpressionArithmetic.EQUALS_NULL); |
| 63 | currentGroup = (currentGroup == null) ? |
| 64 | expr : |
| 65 | new ExpressionArithmetic( currentGroup, expr, ExpressionArithmetic.AND ); |
| 66 | } |
| 67 | } |
| 68 | expressions = internalExpressions; |
| 69 | for(int c=0; c<expressions.size(); c++){ |
| 70 | addColumn(new ColumnExpression(expressions.get(c))); |
| 71 | } |
| 72 | |
| 73 | patchExpressions( cmd.columnExpressions ); |
| 74 | if(having != null) having = patchExpression( having ); |
| 75 | patchExpressions( orderBy ); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Add a expression to the internal expression list if not exist in this list. |
| 80 | * It will be added named columns in the GROUP BY clause. |
| 81 | * @param expr The expression to added. |
| 82 | * @return the position in the internal list |
| 83 | */ |
| 84 | final private int addInternalExpressionFromGroupBy(Expression expr) throws SQLException{ |
| 85 | int type = expr.getType(); |
| 86 | if(type >= Expression.GROUP_BEGIN){ |
| 87 | throw Utils.createSQLException("Aggregate function are not valid in the GROUP BY clause. ("+expr+")"); |
| 88 | }else{ |
| 89 | int idx = internalExpressions.indexOf(expr); |
| 90 | if(idx >= 0) return idx; |
| 91 | internalExpressions.add(expr); |
| 92 | return internalExpressions.size()-1; |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | |
| 97 | /** |
| 98 | * Add a expression to the internal expression list if not exist in this list. |
| 99 | * It will be added aggregate functions from the SELECT, HAVING and ORDER BY clause. |
| 100 | * @param expr The expression to added. |
| 101 | * @return the position in the internal list |
| 102 | */ |
| 103 | final private int addInternalExpressionFromSelect(Expression expr) throws SQLException{ |
| 104 | int type = expr.getType(); |
| 105 | if(type == Expression.NAME){ |
| 106 | int idx = internalExpressions.indexOf(expr); |
| 107 | if(idx >= 0) return idx; |
| 108 | throw Utils.createSQLException("Expression '" + expr + "' is not part of a aggregate function or GROUP BY clause."); |
| 109 | }else |
| 110 | if(type >= Expression.GROUP_BEGIN){ |
| 111 | int idx = internalExpressions.indexOf(expr); |
| 112 | if(idx >= 0) return idx; |
| 113 | internalExpressions.add(expr); |
| 114 | return internalExpressions.size()-1; |
| 115 | }else{ |
| 116 | //if a function or aritmethik expresion is already in the group by the it is ok |
| 117 | int idx = internalExpressions.indexOf(expr); |
| 118 | if(idx >= 0) return idx; |
| 119 | Expression[] params = expr.getParams(); |
| 120 | if(params != null){ |
| 121 | for(int p=0; p<params.length; p++){ |
| 122 | addInternalExpressionFromSelect( params[p]); |
| 123 | } |
| 124 | } |
| 125 | return -1; |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | |
| 130 | /** |
| 131 | * Patch all external ExpressionName in the list (SELECT clause) |
| 132 | * that it link to the the internal RowSource. |
| 133 | */ |
| 134 | final private void patchExpressions(Expressions exprs) throws SQLException{ |
| 135 | if(exprs == null) return; |
| 136 | for(int i=0; i<exprs.size(); i++){ |
| 137 | exprs.set(i, patchExpression(exprs.get(i))); |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | |
| 142 | final private void patchExpressions(Expression expression) throws SQLException{ |
| 143 | Expression[] params = expression.getParams(); |
| 144 | if(params == null) return; |
| 145 | for(int i=0; i<params.length; i++){ |
| 146 | expression.setParamAt( patchExpression(params[i]), i); |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | |
| 151 | /** |
| 152 | * Patch a single Expression. The caller need to replace the original Object |
| 153 | * if the return value return another object. |
| 154 | * @param expr the Expression to patch |
| 155 | * @return on simple columns and Aggregatfunction the original Expression is return as patch. |
| 156 | */ |
| 157 | final private Expression patchExpression(Expression expr) throws SQLException{ |
| 158 | //find the index in the internalExpression list |
| 159 | int idx = addInternalExpressionFromSelect( expr ); |
| 160 | if(idx>=0){ |
| 161 | Expression origExpression = expr; |
| 162 | ExpressionName exprName; |
| 163 | if(expr instanceof ExpressionName){ |
| 164 | exprName = (ExpressionName)expr; |
| 165 | }else{ |
| 166 | // this can only occur if in the GROUP BY clause are a function or arithmetic expression |
| 167 | // and a equals expression is used in SELECT, GROUP BY or HAVING |
| 168 | expr = exprName = new ExpressionName(expr.getAlias()); |
| 169 | } |
| 170 | // patch the expression and set a new DataSource |
| 171 | Column column = exprName.getColumn(); |
| 172 | if(column == null){ |
| 173 | column = new Column(); |
| 174 | exprName.setFrom(this, idx, column); |
| 175 | switch(exprName.getType()){ |
| 176 | case Expression.MAX: |
| 177 | case Expression.MIN: |
| 178 | case Expression.FIRST: |
| 179 | case Expression.LAST: |
| 180 | case Expression.SUM: |
| 181 | Expression baseExpression = exprName.getParams()[0]; |
| 182 | column.setPrecision(baseExpression.getPrecision()); |
| 183 | column.setScale(baseExpression.getScale()); |
| 184 | break; |
| 185 | default: |
| 186 | column.setPrecision(origExpression.getPrecision()); |
| 187 | column.setScale(origExpression.getScale()); |
| 188 | } |
| 189 | column.setDataType(exprName.getDataType()); |
| 190 | }else{ |
| 191 | exprName.setFrom(this, idx, column); |
| 192 | } |
| 193 | }else{ |
| 194 | patchExpressions(expr); |
| 195 | } |
| 196 | return expr; |
| 197 | } |
| 198 | |
| 199 | |
| 200 | |
| 201 | final void execute() throws Exception{ |
| 202 | super.execute(); |
| 203 | from.execute(); |
| 204 | NextRow: |
| 205 | while(from.next()){ |
| 206 | beforeFirst(); |
| 207 | while(next()){ |
| 208 | if(currentGroup == null || currentGroup.getBoolean()){ |
| 209 | accumulateRow(); |
| 210 | continue NextRow; |
| 211 | } |
| 212 | } |
| 213 | // add a new row to the GroupResult |
| 214 | addGroupRow(); |
| 215 | accumulateRow(); |
| 216 | } |
| 217 | |
| 218 | if(getRowCount() == 0 && groupBy == null){ |
| 219 | //special handling for SELECT count(*) FROM table |
| 220 | //without GROUP BY and without any rows |
| 221 | addGroupRow(); |
| 222 | } |
| 223 | // reset the row counter |
| 224 | beforeFirst(); |
| 225 | } |
| 226 | |
| 227 | |
| 228 | |
| 229 | /** |
| 230 | * Add a new Row to the MemoryResult. This occur because the |
| 231 | * GROUP BY clause of the current row not relate to an exists row. |
| 232 | * |
| 233 | */ |
| 234 | final private void addGroupRow(){ |
| 235 | // add a new row to the GroupResult |
| 236 | ExpressionValue[] newRow = currentRow = new ExpressionValue[ expressions.size()]; |
| 237 | for(int i=0; i<newRow.length; i++){ |
| 238 | Expression expr = expressions.get(i); |
| 239 | int type = expr.getType(); |
| 240 | if(type < Expression.GROUP_BEGIN) type = Expression.GROUP_BY; |
| 241 | newRow[i] = new ExpressionValue( type ); |
| 242 | } |
| 243 | addRow(newRow); |
| 244 | } |
| 245 | |
| 246 | |
| 247 | final private void accumulateRow() throws Exception{ |
| 248 | for(int i=0; i<currentRow.length; i++){ |
| 249 | Expression src = expressions.get(i); |
| 250 | currentRow[i].accumulate(src); |
| 251 | } |
| 252 | } |
| 253 | } |