Fix #1686: add support for creating views with "IF NOT EXISTS" clause (#1690)

Author: zaza

src/main/java/net/sf/jsqlparser/statement/create/view/CreateView.java

@@ -30,6 +30,7 @@ public class CreateView implements Statement {
     private ForceOption force = ForceOption.NONE;
     private TemporaryOption temp = TemporaryOption.NONE;
     private boolean withReadOnly = false;
+    private boolean ifNotExists = false;
 
     @Override
     public void accept(StatementVisitor statementVisitor) {
@@ -103,6 +104,14 @@ public void setWithReadOnly(boolean withReadOnly) {
         this.withReadOnly = withReadOnly;
     }
 
+    public boolean isIfNotExists() {
+        return ifNotExists;
+    }
+
+    public void setIfNotExists(boolean ifNotExists) {
+        this.ifNotExists = ifNotExists;
+    }
+
     @Override
     public String toString() {
         StringBuilder sql = new StringBuilder("CREATE ");
@@ -129,6 +138,9 @@ public String toString() {
         }
         sql.append("VIEW ");
         sql.append(view);
+        if (ifNotExists) {
+            sql.append(" IF NOT EXISTS");
+        }
         if (columnNames != null) {
             sql.append(PlainSelect.getStringList(columnNames, true, true));
         }

src/main/java/net/sf/jsqlparser/util/deparser/CreateViewDeParser.java

@@ -60,6 +60,9 @@ public void deParse(CreateView createView) {
             buffer.append("MATERIALIZED ");
         }
         buffer.append("VIEW ").append(createView.getView().getFullyQualifiedName());
+        if (createView.isIfNotExists()) {
+            buffer.append(" IF NOT EXISTS");
+        }
         if (createView.getColumnNames() != null) {
             buffer.append(PlainSelect.getStringList(createView.getColumnNames(), true, true));
         }

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -5486,6 +5486,7 @@ CreateView CreateView():
     ]
     [ <K_MATERIALIZED> { createView.setMaterialized(true);} ]
     <K_VIEW> view=Table() { createView.setView(view); }
+    [ LOOKAHEAD(3) <K_IF> <K_NOT> <K_EXISTS> {createView.setIfNotExists(true);} ]
     [ columnNames = ColumnsNamesList() { createView.setColumnNames(columnNames); } ]
     <K_AS>
     select=SelectWithWithItems( ) { createView.setSelect(select); }

src/test/java/net/sf/jsqlparser/statement/create/CreateViewTest.java

@@ -18,6 +18,8 @@
 import static net.sf.jsqlparser.test.TestUtils.*;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import org.junit.jupiter.api.Test;
 
 public class CreateViewTest {
@@ -121,4 +123,19 @@ public void testCreateTemporaryViewIssue665() throws JSQLParserException {
     public void testCreateWithReadOnlyViewIssue838() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("CREATE VIEW v14(c1, c2) AS SELECT c1, C2 FROM t1 WITH READ ONLY");
     }
+
+    @Test
+    public void testCreateViewIfNotExists() throws JSQLParserException {
+        String stmt = "CREATE VIEW myview IF NOT EXISTS AS SELECT * FROM mytab";
+        CreateView createView = (CreateView) assertSqlCanBeParsedAndDeparsed(stmt);
+        assertTrue(createView.isIfNotExists());
+    }
+    
+    @Test
+    public void testCreateMaterializedViewIfNotExists() throws JSQLParserException {
+        String stmt = "CREATE MATERIALIZED VIEW myview IF NOT EXISTS AS SELECT * FROM mytab";
+        CreateView createView = (CreateView) assertSqlCanBeParsedAndDeparsed(stmt);
+        assertTrue(createView.isMaterialized());
+        assertTrue(createView.isIfNotExists());
+    }
 }