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1 package com.quadcap.sql;
2
3
40
41 import java.io.IOException  ;
42
43 import java.util.ArrayList ;
44 import java.util.Enumeration ;
45 import java.util.HashMap ;
46 import java.util.Iterator ;
47 import java.util.Map ;
48
49 import java.sql.SQLException ;
50
51 import com.quadcap.sql.file.BlockFile;
52 import com.quadcap.sql.file.ByteUtil;
53
54 import com.quadcap.sql.index.Btree;
55 import com.quadcap.sql.index.BCursor;
56
57 import com.quadcap.util.Debug;
58
59
64
65 public class StmtDropTable implements Stmt {
66 Map deleted;
67 String tableName;
68 Relation table;
69 boolean view;
70 boolean restrict;
71
72 public StmtDropTable() {}
73
74 public StmtDropTable(String name, boolean view, boolean restrict) {
75 this.tableName = name;
76 this.view = view;
77 this.restrict = restrict;
78 }
79
80 public void execute(Session session) throws IOException , SQLException {
81 session.getTableWriteLock("#Schema");
82 session.getTableWriteLock(tableName);
83 Database db = session.getDatabase();
84 table = db.getRelation(tableName);
85 if (table == null) {
86 throw new SQLException ("no such " + getType() +
87 ": " + tableName, "42000");
88 }
89
90 Enumeration views = db.getViews(tableName);
91 if (restrict) {
92 if (views.hasMoreElements()) {
93 throw new SQLException ("Can't drop " + getType() +
94 " with RESTRICT because of" +
95 " referencing view: " + views.nextElement(),
96 "23000");
97 }
98 if (table instanceof Table) {
99 Table t = (Table)table;
100 int num = t.getNumConstraints();
101 for (int i = 0; i < num; i++) {
102 Constraint c = t.getConstraint(i);
103 if (c instanceof ExportedKeyConstraint) {
104 ExportedKeyConstraint ex =
105 (ExportedKeyConstraint)c;
106 if (!ex.getFTableName().equals(tableName)) {
107 throw new SQLException (
108 "Can't drop " + getType() +
109 " with RESTRICT because of " +
110 " referencing constraint: " +
111 ex.getName() + ", table " +
112 ex.getFTableName(),
113 "23000");
114 }
115 }
116 }
117 }
118 }
119
120
121 if (!restrict) {
122 if (deleted == null) deleted = new HashMap ();
123 while (views.hasMoreElements()) {
124 String view1 = views.nextElement().toString();
125 if (!deleted.containsKey(view1)) {
126 deleted.put(view1, "");
127 StmtDropTable t = new StmtDropTable(view1, true, false);
128 t.deleted = deleted;
129 t.execute(session);
130 }
131 }
132 }
133
134 if (table instanceof Table) {
136 IndexConstraint ic = null;
139 ArrayList list = new ArrayList ();
140 Table t = (Table)table;
141 ic = t.getAnyIndex(session);
142 int num = t.getNumConstraints();
143 Constraint[] cv = new Constraint[num];
144 for (int i = 0; i < num; i++) {
145 cv[i] = t.getConstraint(i);
146 }
147 for (int i = 0 ; i < num; i++) {
148 Constraint c = cv[i];
149 if (c instanceof ForeignKeyConstraint) {
150 ForeignKeyConstraint fc = (ForeignKeyConstraint)c;
151 if (!fc.isSelfReferencing(db)) {
152 DeleteConstraint.deleteForeign(session, fc);
153 }
154 }
155 if (c != ic) {
156 session.doStep(new DeleteConstraint(session, t, c));
157 }
158 }
159 deleteRows(session, t, ic);
161
162 session.doStep(new DeleteConstraint(session, t, ic));
164 }
165
166 session.doStep(new DropTable(session, table));
168 }
169
170 final void deleteRows(Session session, Table t, IndexConstraint c)
171 throws IOException , SQLException
172 {
173 Database db = session.getDatabase();
174 BlockFile file = db.getFile();
175 Btree index = c.getIndex(db);
176 BCursor bc = index.getCursor();
177 try {
178 while (bc.next()) {
179 session.doStep(new DeleteRow(session, t, bc.getValAsLong()));
180 }
181 } finally {
182 bc.release();
183 }
184 }
185
186 String getType() {
187 return view ? "view" : "table";
188 }
189 }
190 |
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