diff --git a/README.md b/README.md
index b0f49e6..5dca9a0 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ The following operators are added: (Credit goes to Ahmad Baitalmal)
 * isnot null
 
 Previously I was hoping to make the query as similar to SQL `WHERE` clause as possible. Later I found a problem parsing the term `PRIORITY>5`. The tokenizer split it as `PRI`, `OR`, `ITY`, `>`, `5`, since `OR` was then an operator, which is terribly wrong. At that point, I thought of two choices:				
-1. to force the query expression to contain at least one white space between tokens, thus `PRIORITY>5` should be written as `PRIORITY > 5`;		
+1. to force the query expression to contain at least one white space between tokens, thus `PRIORITY>5` should be written as `PRIORITY > 5`;
 2. to replace operators as follows:		
 
 * `AND` to `&&`
diff --git a/jsonql_test.go b/jsonql_test.go
index 054cb2b..d6e5c04 100644
--- a/jsonql_test.go
+++ b/jsonql_test.go
@@ -16,7 +16,9 @@ func TestParse(t *testing.T) {
       "Golang",
       "Java",
       "C"
-    ]
+	],
+	"comments": "",
+	"score": 40
   },
   {
     "name": "enny",
@@ -25,7 +27,10 @@ func TestParse(t *testing.T) {
       "IC",
       "Electric design",
       "Verification"
-    ]
+    ],
+	"comments": "2nd record",
+	"score": 10
+
   },
   {
     "name": "sam",
@@ -34,7 +39,9 @@ func TestParse(t *testing.T) {
       "Eating",
       "Sleeping",
       "Crawling"
-    ]
+		],
+	"comments": "3rd record",
+	"score": 30
   }
 ]
 `
@@ -49,7 +56,20 @@ func TestParse(t *testing.T) {
 	}{
 		{"name='elgs'", 1},
 		{"gender='f'", 1},
+		{"comments='2nd record'", 1},
+		{"comments=\"\"", 1},
+		{"comments=\"\"", 1},
 		{"skills.[1]='Sleeping'", 1},
+		{"skills contains 'Sleeping'", 1},
+		{"skills contains 'Awake'", 0},
+		{"name contains 'lgs'", 1},
+		{"name contains 'e'", 2},
+		{"'Sleeping' in skills", 1},
+		{"'Verification' notin skills", 2},
+		{"'Awake' in skills", 0},
+		{"'lgs' in name", 1},
+		{"'e' in name", 2},
+		{"score > 10 && score < 40", 1},
 	}
 	var fail = []struct {
 		in string
@@ -61,9 +81,13 @@ func TestParse(t *testing.T) {
 			t.Error(v.in, err)
 		}
 		fmt.Println(v.in, result)
-		//		if v.ex != result {
-		//			t.Error("Expected:", v.ex, "actual:", result)
-		//		}
+		numResults, ok := result.([]interface{})
+		if !ok {
+			t.Error("Failed to convert result")
+		}
+		if len(numResults) != v.ex {
+			t.Errorf("Got %v results, expected %v for `%v`", len(numResults), v.ex, v.in)
+		}
 	}
 	for range fail {
 
diff --git a/sql_operators.go b/sql_operators.go
index 38fd524..0a6b9c0 100644
--- a/sql_operators.go
+++ b/sql_operators.go
@@ -32,8 +32,48 @@ func evalToken(symbolTable interface{}, token string) (interface{}, error) {
 	return jq.Query(token)
 }
 
+func opIn(symbolTable interface{}, left string, right string) (string, error) {
+	l, lUndefined := evalToken(symbolTable, left)
+	if lUndefined != nil {
+		return "false", nil
+	}
+	ls := l.(string)
+
+	r, rUndefined := evalToken(symbolTable, right)
+	if rUndefined != nil {
+		return "false", nil
+	}
+
+	switch r.(type) {
+	case []interface{}:
+		jsn, _ := r.([]interface{})
+		for _, j := range jsn {
+			if s, ok := j.(string); ok {
+				if s == ls {
+					return "true", nil
+				}
+			}
+		}
+		return "false", nil
+	case interface{}:
+		str, ok := r.(string)
+		if !ok {
+			return "false", nil
+		}
+		contains := strings.Contains(str, ls)
+		if contains {
+			return "true", nil
+		}
+		return "false", nil
+
+	default:
+		return "false", nil
+	}
+
+}
+
 var sqlOperators = map[string]*Operator{
-	// Tokenizer will be responsible to put a space before and after each ')OR(', but not priORity.
+	// Tokenizer will be responsible to put a space before and after each ')OR(', but not priority.
 	"||": {
 		Precedence: 1,
 		Eval: func(symbolTable interface{}, left string, right string) (string, error) {
@@ -62,6 +102,62 @@ var sqlOperators = map[string]*Operator{
 			return strconv.FormatBool(l && r), nil
 		},
 	},
+	"contains": {
+		Precedence: 6,
+		Eval: func(symbolTable interface{}, left string, right string) (string, error) {
+			l, lUndefined := evalToken(symbolTable, left)
+			if lUndefined != nil {
+				return "false", nil
+			}
+			r, rUndefined := evalToken(symbolTable, right)
+			if rUndefined != nil {
+				return "false", nil
+			}
+			rs := r.(string)
+
+			switch l.(type) {
+			case []interface{}:
+				jsn, _ := l.([]interface{})
+				for _, j := range jsn {
+					if s, ok := j.(string); ok {
+						if s == rs {
+							return "true", nil
+						}
+					}
+				}
+				return "false", nil
+			case interface{}:
+				str, ok := l.(string)
+				if !ok {
+					return "false", nil
+				}
+				contains := strings.Contains(str, rs)
+				if contains {
+					return "true", nil
+				}
+				return "false", nil
+
+			default:
+				return "false", nil
+			}
+
+		},
+	},
+	"in": {
+		Precedence: 6,
+		Eval:       opIn,
+	},
+	"notin": {
+		Precedence: 6,
+		Eval: func(symbolTable interface{}, left string, right string) (string, error) {
+			s, err := opIn(symbolTable, left, right)
+			if err != nil {
+				return s, err
+			}
+			b, _ := strconv.ParseBool(s)
+			return strconv.FormatBool(!b), err
+		},
+	},
 	"is": {
 		Precedence: 5,
 		Eval: func(symbolTable interface{}, left string, right string) (string, error) {