Merge remote-tracking branch 'upstream/master'

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

@@ -797,6 +797,9 @@ public class SQLEvalVisitorUtils {
             wallConditionContext.setConstArithmetic(true);
         }
 
+        leftValue = processValue(leftValue);
+        rightValue = processValue(rightValue);
+
         if (leftValue == null || rightValue == null) {
             return false;
         }
@@ -890,6 +893,17 @@ public class SQLEvalVisitorUtils {
         return false;
     }
 
+    @SuppressWarnings("rawtypes")
+    private static Object processValue(Object value) {
+        if (value instanceof List) {
+            List list = (List) value;
+            if (list.size() == 1) {
+                return processValue(list.get(0));
+            }
+        }
+        return value;
+    }
+
     private static boolean isAlwayTrueLikePattern(SQLExpr x) {
         if (x instanceof SQLCharExpr) {
             String text = ((SQLCharExpr) x).getText();
@@ -1223,7 +1237,7 @@ public class SQLEvalVisitorUtils {
         }
 
         if (a instanceof String || b instanceof String) {
-            return ((String) a).compareTo((String) b) > 0;
+            return castToString(a).compareTo(castToString(b)) > 0;
         }
 
         if (a instanceof BigDecimal || b instanceof BigDecimal) {

src/main/java/com/alibaba/druid/sql/visitor/functions/Isnull.java

@@ -38,8 +38,10 @@ public class Isnull implements Function {
         SQLExpr condition = parameters.get(0);
         condition.accept(visitor);
         Object itemValue = condition.getAttributes().get(EVAL_VALUE);
-        if (itemValue == null || itemValue == EVAL_VALUE_NULL) {
+        if (itemValue == EVAL_VALUE_NULL) {
             return Boolean.TRUE;
+        } else if (itemValue == null) {
+            return null;
         } else {
             return Boolean.FALSE;
         }

src/main/java/com/alibaba/druid/sql/visitor/functions/Right.java

@@ -22,10 +22,10 @@ import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
 import com.alibaba.druid.sql.visitor.SQLEvalVisitor;
 import com.alibaba.druid.sql.visitor.SQLEvalVisitorUtils;
 
-
 public class Right implements Function {
+
     public final static Right instance = new Right();
-    
+
     public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
         if (x.getParameters().size() != 2) {
             return SQLEvalVisitor.EVAL_ERROR;
@@ -45,7 +45,11 @@ public class Right implements Function {
         String strValue = param0Value.toString();
         int intValue = SQLEvalVisitorUtils.castToInteger(param1Value);
 
-        String result = strValue.substring(strValue.length() - intValue, strValue.length());
+        int start = strValue.length() - intValue;
+        if (start < 0) {
+            start = 0;
+        }
+        String result = strValue.substring(start, strValue.length());
         return result;
     }
 }