improved oracle sql parser for pl/sql if.

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleOutputVisitor.java

@@ -1977,8 +1977,18 @@ public class OracleOutputVisitor extends SQLASTOutputVisitor implements OracleAS
     @Override
     public boolean visit(SQLIfStatement x) {
         print0(ucase ? "IF " : "if ");
+        int lines = this.lines;
+        incrementIndent();
         x.getCondition().accept(this);
-        print0(ucase ? " THEN" : " then");
+        decrementIndent();
+
+        if (lines != this.lines) {
+            println();
+        } else {
+            print(' ');
+        }
+        print0(ucase ? "THEN" : "then");
+
         incrementIndent();
         println();
         for (int i = 0, size = x.getStatements().size(); i < size; ++i) {

src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java

@@ -63,6 +63,8 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
 
     protected boolean shardingSupport = false;
 
+    protected transient int lines = 0;
+
     public SQLASTOutputVisitor(Appendable appender){
         this.appender = appender;
     }
@@ -283,6 +285,7 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
         }
 
         print0("\n");
+        lines++;
         printIndent();
     }